Fix Include OpenAPI support. Fix bug with single include being considered 'OneOf' even though that is an overcomplication of the schema. Add tests for single include type and two include types on document

Feature/open api schema

JSONAPI.playground/Pages/Full Client & Server Example.xcplaygroundpage/Contents.swift

@@ -1,5 +1,6 @@
 import Foundation
 import JSONAPI
+import Poly
 
 // MARK: - Preamble (setup)
 

JSONAPI.playground/Pages/OpenAPI Documentation.xcplaygroundpage/Contents.swift

@@ -3,6 +3,7 @@
 import Foundation
 import JSONAPI
 import JSONAPIOpenAPI
+import Poly
 
 // print Entity Schema
 let encoder = JSONEncoder()
@@ -15,16 +16,31 @@ print("====")
 print(personSchemaData.map { String(data: $0, encoding: .utf8)! } ?? "Schema Construction Failed")
 print("====")
 
-let dogDocumentSchemaData = try? encoder.encode(SingleDogDocument.openAPINodeWithExample())
+let dogDocumentSchemaData = try? encoder.encode(SingleDogDocument.openAPINodeWithExample(using: encoder))
 
 print("Dog Document Schema")
 print("====")
 print(dogDocumentSchemaData.map { String(data: $0, encoding: .utf8)! } ?? "Schema Construction Failed")
 print("====")
 
-let batchPersonSchemaData = try? encoder.encode(BatchPeopleDocument.openAPINodeWithExample())
+let batchPersonSchemaData = try? encoder.encode(BatchPeopleDocument.openAPINodeWithExample(using: encoder))
 
 print("Batch Person Document Schema")
 print("====")
 print(batchPersonSchemaData.map { String(data: $0, encoding: .utf8)! } ?? "Schema Construction Failed")
 print("====")
+
+let tmp: [String: OpenAPIComponents.SchemasDict.RefType] = [
+	"BatchPerson": try! BatchPeopleDocument.openAPINodeWithExample()
+]
+
+let components = OpenAPIComponents(schemas: tmp)
+
+let batchPeopleRef = JSONReference(type: \OpenAPIComponents.schemas, selector: "BatchPerson")
+
+let tmp2 = JSONNode.reference(batchPeopleRef)
+
+print("====")
+print("====")
+//print(String(data: try! encoder.encode(components), encoding: .utf8)!)
+print(String(data: try! encoder.encode(tmp2), encoding: .utf8)!)

README.md

@@ -843,4 +843,4 @@ This Framework is currently undocumented, but familiarity with `SwiftCheck` will
 # JSONAPI+OpenAPI
 The `JSONAPIOpenAPI` framework adds the ability to generate OpenAPI compliant JSON documentation of a JSONAPI Document.
 
-This library is in its infancy. The documentation will grow as the framework becomes more complete.
+*This library is in its infancy. The documentation will grow as the framework becomes more complete.*

Sources/JSONAPIOpenAPI/JSONAPI/JSONAPIInclude+OpenAPI.swift

@@ -6,10 +6,11 @@
 //
 
 import JSONAPI
+import Foundation
 
-extension Includes: OpenAPINodeType where I: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
-		let includeNode = try I.openAPINode()
+extension Includes: OpenAPIEncodedNodeType where I: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
+		let includeNode = try I.openAPINode(using: encoder)
 
 		return .array(.init(format: .generic,
 							required: true),
@@ -18,114 +19,114 @@ extension Includes: OpenAPINodeType where I: OpenAPINodeType {
 	}
 }
 
-extension Include0: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include0: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		throw OpenAPITypeError.invalidNode
 	}
 }
 
-extension Include1: OpenAPINodeType where A: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
-		return try .one(of: [A.openAPINode()])
+extension Include1: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
+		return try A.openAPINode(using: encoder)
 	}
 }
 
-extension Include2: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include2: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder)
 		])
 	}
 }
 
-extension Include3: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include3: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder)
 			])
 	}
 }
 
-extension Include4: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType, D: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include4: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType, D: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode(),
-			D.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder),
+			D.openAPINode(using: encoder)
 			])
 	}
 }
 
-extension Include5: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType, D: OpenAPINodeType, E: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include5: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType, D: OpenAPIEncodedNodeType, E: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode(),
-			D.openAPINode(),
-			E.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder),
+			D.openAPINode(using: encoder),
+			E.openAPINode(using: encoder)
 			])
 	}
 }
 
-extension Include6: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType, D: OpenAPINodeType, E: OpenAPINodeType, F: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include6: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType, D: OpenAPIEncodedNodeType, E: OpenAPIEncodedNodeType, F: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode(),
-			D.openAPINode(),
-			E.openAPINode(),
-			F.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder),
+			D.openAPINode(using: encoder),
+			E.openAPINode(using: encoder),
+			F.openAPINode(using: encoder)
 			])
 	}
 }
 
-extension Include7: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType, D: OpenAPINodeType, E: OpenAPINodeType, F: OpenAPINodeType, G: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include7: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType, D: OpenAPIEncodedNodeType, E: OpenAPIEncodedNodeType, F: OpenAPIEncodedNodeType, G: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode(),
-			D.openAPINode(),
-			E.openAPINode(),
-			F.openAPINode(),
-			G.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder),
+			D.openAPINode(using: encoder),
+			E.openAPINode(using: encoder),
+			F.openAPINode(using: encoder),
+			G.openAPINode(using: encoder)
 			])
 	}
 }
 
-extension Include8: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType, D: OpenAPINodeType, E: OpenAPINodeType, F: OpenAPINodeType, G: OpenAPINodeType, H: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include8: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType, D: OpenAPIEncodedNodeType, E: OpenAPIEncodedNodeType, F: OpenAPIEncodedNodeType, G: OpenAPIEncodedNodeType, H: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode(),
-			D.openAPINode(),
-			E.openAPINode(),
-			F.openAPINode(),
-			G.openAPINode(),
-			H.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder),
+			D.openAPINode(using: encoder),
+			E.openAPINode(using: encoder),
+			F.openAPINode(using: encoder),
+			G.openAPINode(using: encoder),
+			H.openAPINode(using: encoder)
 			])
 	}
 }
 
-extension Include9: OpenAPINodeType where A: OpenAPINodeType, B: OpenAPINodeType, C: OpenAPINodeType, D: OpenAPINodeType, E: OpenAPINodeType, F: OpenAPINodeType, G: OpenAPINodeType, H: OpenAPINodeType, I: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Include9: OpenAPIEncodedNodeType where A: OpenAPIEncodedNodeType, B: OpenAPIEncodedNodeType, C: OpenAPIEncodedNodeType, D: OpenAPIEncodedNodeType, E: OpenAPIEncodedNodeType, F: OpenAPIEncodedNodeType, G: OpenAPIEncodedNodeType, H: OpenAPIEncodedNodeType, I: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return try .one(of: [
-			A.openAPINode(),
-			B.openAPINode(),
-			C.openAPINode(),
-			D.openAPINode(),
-			E.openAPINode(),
-			F.openAPINode(),
-			G.openAPINode(),
-			H.openAPINode(),
-			I.openAPINode()
+			A.openAPINode(using: encoder),
+			B.openAPINode(using: encoder),
+			C.openAPINode(using: encoder),
+			D.openAPINode(using: encoder),
+			E.openAPINode(using: encoder),
+			F.openAPINode(using: encoder),
+			G.openAPINode(using: encoder),
+			H.openAPINode(using: encoder),
+			I.openAPINode(using: encoder)
 			])
 	}
 }

Sources/JSONAPIOpenAPI/JSONAPI/JSONAPITypes+OpenAPI.swift

@@ -6,11 +6,17 @@
 //
 
 import JSONAPI
+import Foundation
 import AnyCodable
 
 private protocol _Optional {}
 extension Optional: _Optional {}
 
+private protocol Wrapper {
+	associatedtype Wrapped
+}
+extension Optional: Wrapper {}
+
 extension Attribute: OpenAPINodeType where RawValue: OpenAPINodeType {
 	static public func openAPINode() throws -> JSONNode {
 		// If the RawValue is not required, we actually consider it
@@ -47,15 +53,40 @@ extension Attribute: WrappedRawOpenAPIType where RawValue: RawOpenAPINodeType {
 	}
 }
 
+extension Attribute: GenericOpenAPINodeType where RawValue: GenericOpenAPINodeType {
+	public static func genericOpenAPINode(using encoder: JSONEncoder) throws -> JSONNode {
+		// If the RawValue is not required, we actually consider it
+		// nullable. To be not required is for the Attribute itself
+		// to be optional.
+		if try !RawValue.genericOpenAPINode(using: encoder).required {
+			return try RawValue.genericOpenAPINode(using: encoder).requiredNode().nullableNode()
+		}
+		return try RawValue.genericOpenAPINode(using: encoder)
+	}
+}
+
+extension Attribute: DateOpenAPINodeType where RawValue: DateOpenAPINodeType {
+	public static func dateOpenAPINodeGuess(using encoder: JSONEncoder) -> JSONNode? {
+		// If the RawValue is not required, we actually consider it
+		// nullable. To be not required is for the Attribute itself
+		// to be optional.
+		if
+			!(RawValue.dateOpenAPINodeGuess(using: encoder)?.required ?? true) {
+			return RawValue.dateOpenAPINodeGuess(using: encoder)?.requiredNode().nullableNode()
+		}
+		return RawValue.dateOpenAPINodeGuess(using: encoder)
+	}
+}
+
 extension Attribute: AnyJSONCaseIterable where RawValue: CaseIterable, RawValue: Codable {
-	public static var allCases: [AnyCodable] {
-		return (try? allCases(from: Array(RawValue.allCases))) ?? []
+	public static func allCases(using encoder: JSONEncoder) -> [AnyCodable] {
+		return (try? allCases(from: Array(RawValue.allCases), using: encoder)) ?? []
 	}
 }
 
 extension Attribute: AnyWrappedJSONCaseIterable where RawValue: AnyJSONCaseIterable {
-	public static var allCases: [AnyCodable] {
-		return RawValue.allCases
+	public static func allCases(using encoder: JSONEncoder) -> [AnyCodable] {
+		return RawValue.allCases(using: encoder)
 	}
 }
 
@@ -71,6 +102,8 @@ extension TransformedAttribute: OpenAPINodeType where RawValue: OpenAPINodeType
 	}
 }
 
+// TODO: conform TransformedAttribute to all of the above protocols that Attribute conforms to.
+
 extension RelationshipType {
 	static func relationshipNode(nullable: Bool, jsonType: String) -> JSONNode {
 		let propertiesDict: [String: JSONNode] = [
@@ -121,17 +154,19 @@ extension ToManyRelationship: OpenAPINodeType {
 	}
 }
 
-extension Entity: OpenAPINodeType where Description.Attributes: Sampleable, Description.Relationships: Sampleable {
-	public static func openAPINode() throws -> JSONNode {
+extension Entity: OpenAPIEncodedNodeType where Description.Attributes: Sampleable, Description.Relationships: Sampleable {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		// NOTE: const for json `type` not supported by OpenAPI 3.0
 		//		Will use "enum" with one possible value for now.
 
 		// TODO: metadata, links
 
-		let idNode = JSONNode.string(.init(format: .generic,
-										   required: true),
-									 .init())
-		let idProperty = ("id", idNode)
+		let idNode: JSONNode? = Id.RawType.self != Unidentified.self
+			? JSONNode.string(.init(format: .generic,
+									required: true),
+							  .init())
+			: nil
+		let idProperty = idNode.map { ("id", $0) }
 
 		let typeNode = JSONNode.string(.init(format: .generic,
 											 required: true,
@@ -141,13 +176,13 @@ extension Entity: OpenAPINodeType where Description.Attributes: Sampleable, Desc
 
 		let attributesNode: JSONNode? = Description.Attributes.self == NoAttributes.self
 			? nil
-			: try Description.Attributes.genericObjectOpenAPINode()
+			: try Description.Attributes.genericOpenAPINode(using: encoder)
 
 		let attributesProperty = attributesNode.map { ("attributes", $0) }
 
 		let relationshipsNode: JSONNode? = Description.Relationships.self == NoRelationships.self
 			? nil
-			: try Description.Relationships.genericObjectOpenAPINode()
+			: try Description.Relationships.genericOpenAPINode(using: encoder)
 
 		let relationshipsProperty = relationshipsNode.map { ("relationships", $0) }
 
@@ -164,34 +199,34 @@ extension Entity: OpenAPINodeType where Description.Attributes: Sampleable, Desc
 	}
 }
 
-extension SingleResourceBody: OpenAPINodeType where Entity: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
-		return try Entity.openAPINode()
+extension SingleResourceBody: OpenAPIEncodedNodeType where Entity: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
+		return try Entity.openAPINode(using: encoder)
 	}
 }
 
-extension ManyResourceBody: OpenAPINodeType where Entity: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension ManyResourceBody: OpenAPIEncodedNodeType where Entity: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		return .array(.init(format: .generic,
 							required: true),
-					  .init(items: try Entity.openAPINode()))
+					  .init(items: try Entity.openAPINode(using: encoder)))
 	}
 }
 
-extension Document: OpenAPINodeType where PrimaryResourceBody: OpenAPINodeType, IncludeType: OpenAPINodeType {
-	public static func openAPINode() throws -> JSONNode {
+extension Document: OpenAPIEncodedNodeType where PrimaryResourceBody: OpenAPIEncodedNodeType, IncludeType: OpenAPIEncodedNodeType {
+	public static func openAPINode(using encoder: JSONEncoder) throws -> JSONNode {
 		// TODO: metadata, links, api description, errors
 		// TODO: represent data and errors as the two distinct possible outcomes
 
-		let primaryDataNode: JSONNode? = try PrimaryResourceBody.openAPINode()
+		let primaryDataNode: JSONNode? = try PrimaryResourceBody.openAPINode(using: encoder)
 
 		let primaryDataProperty = primaryDataNode.map { ("data", $0) }
 
 		let includeNode: JSONNode?
 		do {
-			includeNode = try Includes<Include>.openAPINode()
+			includeNode = try Includes<Include>.openAPINode(using: encoder)
 		} catch let err as OpenAPITypeError {
-			guard err == .invalidNode else {
+			guard case .invalidNode = err else {
 				throw err
 			}
 			includeNode = nil

Sources/JSONAPIOpenAPI/OpenAPI/Date+OpenAPI.swift

@@ -0,0 +1,40 @@
+//
+//  Date+OpenAPI.swift
+//  JSONAPIOpenAPI
+//
+//  Created by Mathew Polzin on 1/24/19.
+//
+
+import Foundation
+
+extension Date: DateOpenAPINodeType {
+	public static func dateOpenAPINodeGuess(using encoder: JSONEncoder) -> JSONNode? {
+
+		switch encoder.dateEncodingStrategy {
+		case .deferredToDate, .custom:
+			// I don't know if we can say anything about this case without
+			// encoding the Date and looking at it, which is what `primitiveGuess()`
+			// does.
+			return nil
+
+		case .secondsSince1970,
+			 .millisecondsSince1970:
+			return .number(.init(format: .double,
+								 required: true),
+						   .init())
+
+		case .iso8601:
+			return .string(.init(format: .dateTime,
+								 required: true),
+						   .init())
+
+		case .formatted(let formatter):
+			let hasTime = formatter.timeStyle != .none
+			let format: JSONTypeFormat.StringFormat = hasTime ? .dateTime : .date
+
+			return .string(.init(format: format,
+								 required: true),
+						   .init())
+		}
+	}
+}

Sources/JSONAPIOpenAPI/OpenAPI/OpenAPITypes+Codable.swift

@@ -189,6 +189,266 @@ extension JSONNode: Encodable {
 			var container = encoder.container(keyedBy: SubschemaCodingKeys.self)
 
 			try container.encode(node, forKey: .not)
+
+		case .reference(let reference):
+			var container = encoder.singleValueContainer()
+
+			try container.encode(reference)
 		}
 	}
 }
+
+extension JSONReference: Encodable {
+	private enum CodingKeys: String, CodingKey {
+		case ref = "$ref"
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		let referenceString: String = {
+			switch self {
+			case .file(let reference):
+				return reference
+			case .node(let reference):
+				return "#/\(Root.refName)/\(reference.refName)/\(reference.selector)"
+			}
+		}()
+
+		try container.encode(referenceString, forKey: .ref)
+	}
+}
+
+extension RefDict: Encodable {
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		try container.encode(dict)
+	}
+}
+
+extension OpenAPIResponse.Code: Encodable {
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		let string: String
+		switch self {
+		case .`default`:
+			string = "default"
+
+		case .status(code: let code):
+			string = String(code)
+		}
+
+		try container.encode(string)
+	}
+}
+
+extension OpenAPIRequestBody: Encodable {
+	private enum CodingKeys: String, CodingKey {
+		case description
+		case content
+		case required
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		if description != nil {
+			try container.encode(description, forKey: .description)
+		}
+
+		// Hack to work around Dictionary encoding
+		// itself as an array in this case:
+		let stringKeyedDict = Dictionary(
+			content.map { ($0.key.rawValue, $0.value) },
+			uniquingKeysWith: { $1 }
+		)
+		try container.encode(stringKeyedDict, forKey: .content)
+
+		try container.encode(required, forKey: .required)
+	}
+}
+
+extension OpenAPIPathItem.PathProperties.Operation: Encodable {
+	private enum CodingKeys: String, CodingKey {
+		case tags
+		case summary
+		case description
+		case externalDocs
+		case operationId
+		case parameters
+		case requestBody
+		case responses
+		case callbacks
+		case deprecated
+		case security
+		case servers
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		if tags != nil {
+			try container.encode(tags, forKey: .tags)
+		}
+
+		if summary != nil {
+			try container.encode(summary, forKey: .summary)
+		}
+
+		if description != nil {
+			try container.encode(description, forKey: .description)
+		}
+
+		try container.encode(operationId, forKey: .operationId)
+
+		try container.encode(parameters, forKey: .parameters)
+
+		if requestBody != nil {
+			try container.encode(requestBody, forKey: .requestBody)
+		}
+
+		// Hack to work around Dictionary encoding
+		// itself as an array in this case:
+		let stringKeyedDict = Dictionary(
+			responses.map { ($0.key.rawValue, $0.value) },
+			uniquingKeysWith: { $1 }
+		)
+		try container.encode(stringKeyedDict, forKey: .responses)
+
+		try container.encode(deprecated, forKey: .deprecated)
+	}
+}
+
+extension OpenAPIPathItem.PathProperties: Encodable {
+	private enum CodingKeys: String, CodingKey {
+		case summary
+		case description
+		case servers
+		case parameters
+
+		case get
+		case put
+		case post
+		case delete
+		case options
+		case head
+		case patch
+		case trace
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		if summary != nil {
+			try container.encode(summary, forKey: .summary)
+		}
+
+		if description != nil {
+			try container.encode(description, forKey: .description)
+		}
+
+		try container.encode(parameters, forKey: .parameters)
+
+		if get != nil {
+			try container.encode(get, forKey: .get)
+		}
+
+		if put != nil {
+			try container.encode(put, forKey: .put)
+		}
+
+		if post != nil {
+			try container.encode(post, forKey: .post)
+		}
+
+		if delete != nil {
+			try container.encode(delete, forKey: .delete)
+		}
+
+		if options != nil {
+			try container.encode(options, forKey: .options)
+		}
+
+		if head != nil {
+			try container.encode(head, forKey: .head)
+		}
+
+		if patch != nil {
+			try container.encode(patch, forKey: .patch)
+		}
+
+		if trace != nil {
+			try container.encode(trace, forKey: .trace)
+		}
+	}
+}
+
+extension OpenAPIResponse: Encodable {
+	private enum CodingKeys: String, CodingKey {
+		case description
+		case headers
+		case content
+		case links
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		try container.encode(description, forKey: .description)
+
+		// Hack to work around Dictionary encoding
+		// itself as an array in this case:
+		let stringKeyedDict = Dictionary(
+			content.map { ($0.key.rawValue, $0.value) },
+			uniquingKeysWith: { $1 }
+		)
+		try container.encode(stringKeyedDict, forKey: .content)
+	}
+}
+
+extension OpenAPIPathItem: Encodable {
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.singleValueContainer()
+
+		switch self {
+		case .reference(let reference):
+			try container.encode(reference)
+
+		case .operations(let operations):
+			try container.encode(operations)
+		}
+	}
+}
+
+extension OpenAPISchema: Encodable {
+	private enum CodingKeys: String, CodingKey {
+		case openAPIVersion = "openapi"
+		case info
+		case servers
+		case paths
+		case components
+		case security
+		case tags
+		case externalDocs
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		try container.encode(openAPIVersion, forKey: .openAPIVersion)
+
+		try container.encode(info, forKey: .info)
+
+		// Hack to work around Dictionary encoding
+		// itself as an array in this case:
+		let stringKeyedDict = Dictionary(
+			paths.map { ($0.key.rawValue, $0.value) },
+			uniquingKeysWith: { $1 }
+		)
+		try container.encode(stringKeyedDict, forKey: .paths)
+
+		try container.encode(components, forKey: .components)
+	}
+}

Sources/JSONAPIOpenAPI/OpenAPI/SwiftPrimitiveTypes+OpenAPI.swift

@@ -6,6 +6,7 @@
 //
 
 import AnyCodable
+import Foundation
 
 /**
 
@@ -56,8 +57,14 @@ extension Optional: DoubleWrappedRawOpenAPIType where Wrapped: WrappedRawOpenAPI
 }
 
 extension Optional: AnyJSONCaseIterable where Wrapped: CaseIterable, Wrapped: Codable {
-	public static var allCases: [AnyCodable] {
-		return (try? allCases(from: Array(Wrapped.allCases))) ?? []
+	public static func allCases(using encoder: JSONEncoder) -> [AnyCodable] {
+		return (try? allCases(from: Array(Wrapped.allCases), using: encoder)) ?? []
+	}
+}
+
+extension Optional: DateOpenAPINodeType where Wrapped: DateOpenAPINodeType {
+	static public func dateOpenAPINodeGuess(using encoder: JSONEncoder) -> JSONNode? {
+		return Wrapped.dateOpenAPINodeGuess(using: encoder)?.optionalNode()
 	}
 }
 

Sources/JSONAPIOpenAPI/Sampleable/JSONAPI+Sampleable.swift

@@ -0,0 +1,68 @@
+//
+//  JSONAPI+Sampleable.swift
+//  JSONAPIOpenAPI
+//
+//  Created by Mathew Polzin on 1/24/19.
+//
+
+import JSONAPI
+
+extension NoAttributes: Sampleable {
+	public static var sample: NoAttributes {
+		return .none
+	}
+}
+
+extension NoRelationships: Sampleable {
+	public static var sample: NoRelationships {
+		return .none
+	}
+}
+
+extension NoMetadata: Sampleable {
+	public static var sample: NoMetadata {
+		return .none
+	}
+}
+
+extension NoLinks: Sampleable {
+	public static var sample: NoLinks {
+		return .none
+	}
+}
+
+extension NoAPIDescription: Sampleable {
+	public static var sample: NoAPIDescription {
+		return .none
+	}
+}
+
+extension UnknownJSONAPIError: Sampleable {
+	public static var sample: UnknownJSONAPIError {
+		return .unknownError
+	}
+}
+
+extension Unidentified: Sampleable {
+	public static var sample: Unidentified {
+		return Unidentified()
+	}
+}
+
+extension Attribute: Sampleable where RawValue: Sampleable {
+	public static var sample: Attribute<RawValue> {
+		return .init(value: RawValue.sample)
+	}
+}
+
+extension SingleResourceBody: Sampleable where Entity: Sampleable {
+	public static var sample: SingleResourceBody<Entity> {
+		return .init(entity: Entity.sample)
+	}
+}
+
+extension ManyResourceBody: Sampleable where Entity: Sampleable {
+	public static var sample: ManyResourceBody<Entity> {
+		return .init(entities: Entity.samples)
+	}
+}

Sources/JSONAPIOpenAPI/Sampleable/Sampleable+OpenAPI.swift

@@ -0,0 +1,161 @@
+//
+//  Sampleable+OpenAPI.swift
+//  JSONAPIOpenAPI
+//
+//  Created by Mathew Polzin on 1/24/19.
+//
+
+import Foundation
+import AnyCodable
+
+public typealias SampleableOpenAPIType = Sampleable & GenericOpenAPINodeType
+
+extension Sampleable where Self: Encodable {
+	public static func genericOpenAPINode(using encoder: JSONEncoder) throws -> JSONNode {
+
+		// short circuit for dates
+		if let dateType = self as? Date.Type,
+			let node = try dateType.dateOpenAPINodeGuess(using: encoder) ?? primitiveGuess(using: encoder) {
+			return node
+		}
+
+		let mirror = Mirror(reflecting: Self.sample)
+		let properties: [(String, JSONNode)] = try mirror.children.compactMap { child in
+
+			// see if we can enumerate the possible values
+			let maybeAllCases: [AnyCodable]? = {
+				switch type(of: child.value) {
+				case let valType as AnyJSONCaseIterable.Type:
+					return valType.allCases(using: encoder)
+				case let valType as AnyWrappedJSONCaseIterable.Type:
+					return valType.allCases(using: encoder)
+				default:
+					return nil
+				}
+			}()
+
+			// try to snag an OpenAPI Node
+			let maybeOpenAPINode: JSONNode? = try {
+				switch type(of: child.value) {
+				case let valType as OpenAPINodeType.Type:
+					return try valType.openAPINode()
+
+				case let valType as RawOpenAPINodeType.Type:
+					return try valType.rawOpenAPINode()
+
+				case let valType as WrappedRawOpenAPIType.Type:
+					return try valType.wrappedOpenAPINode()
+
+				case let valType as DoubleWrappedRawOpenAPIType.Type:
+					return try valType.wrappedOpenAPINode()
+
+				case let valType as GenericOpenAPINodeType.Type:
+					return try valType.genericOpenAPINode(using: encoder)
+
+				case let valType as DateOpenAPINodeType.Type:
+					return valType.dateOpenAPINodeGuess(using: encoder)
+
+				default:
+					throw OpenAPITypeError.unknownNodeType(self)
+//					return nil
+				}
+				}()
+
+			// put it all together
+			let newNode: JSONNode?
+			if let allCases = maybeAllCases,
+				let openAPINode = maybeOpenAPINode {
+				newNode = try openAPINode.with(allowedValues: allCases)
+			} else {
+				newNode = maybeOpenAPINode
+			}
+
+			return zip(child.label, newNode) { ($0, $1) }
+		}
+
+		// if there are no properties, let's see if we are dealing
+		// with a primitive.
+		if properties.count == 0,
+			let primitive = try primitiveGuess(using: encoder) {
+			return primitive
+		}
+
+		// There should not be any duplication of keys since these are
+		// property names, but rather than risk runtime exception, we just
+		// fail to the newer value arbitrarily
+		let propertiesDict = Dictionary(properties) { _, value2 in value2 }
+
+		return .object(.init(format: .generic,
+							 required: true),
+					   .init(properties: propertiesDict))
+	}
+
+	private static func primitiveGuess(using encoder: JSONEncoder) throws -> JSONNode? {
+
+		let data = try encoder.encode(PrimitiveWrapper(primitive: Self.sample))
+		let wrappedValue = try JSONSerialization.jsonObject(with: data, options: [.allowFragments])
+
+		guard let wrapperDict = wrappedValue as? [String: Any],
+			wrapperDict.contains(where: { $0.key == "primitive" }) else {
+				throw OpenAPICodableError.primitiveGuessFailed
+		}
+
+		let value = (wrappedValue as! [String: Any])["primitive"]!
+
+		return try {
+			switch type(of: value) {
+			case let valType as OpenAPINodeType.Type:
+				return try valType.openAPINode()
+
+			case let valType as RawOpenAPINodeType.Type:
+				return try valType.rawOpenAPINode()
+
+			case let valType as WrappedRawOpenAPIType.Type:
+				return try valType.wrappedOpenAPINode()
+
+			case let valType as DoubleWrappedRawOpenAPIType.Type:
+				return try valType.wrappedOpenAPINode()
+
+			case let valType as GenericOpenAPINodeType.Type:
+				return try valType.genericOpenAPINode(using: encoder)
+
+			case let valType as DateOpenAPINodeType.Type:
+				return valType.dateOpenAPINodeGuess(using: encoder)
+
+			default:
+				return nil
+			}
+			}() ?? {
+				switch value {
+				case is String:
+					return .string(.init(format: .generic,
+										 required: true),
+								   .init())
+
+				case is Int:
+					return .integer(.init(format: .generic,
+										  required: true),
+									.init())
+
+				case is Double:
+					return .number(.init(format: .double,
+										 required: true),
+								   .init())
+
+				case is Bool:
+					return .boolean(.init(format: .generic,
+										  required: true))
+
+				default:
+					return nil
+				}
+			}()
+	}
+}
+
+// The following wrapper is only needed because JSONEncoder cannot yet encode
+// JSON fragments. It is a very unfortunate limitation that requires silly
+// workarounds in edge cases like this.
+private struct PrimitiveWrapper<Wrapped: Encodable>: Encodable {
+	let primitive: Wrapped
+}

Sources/JSONAPIOpenAPI/Sampleable/Sampleable.swift

@@ -5,8 +5,7 @@
 //  Created by Mathew Polzin on 1/15/19.
 //
 
-import JSONAPI
-import AnyCodable
+import Foundation
 
 /// A Sampleable type can provide a sample value.
 /// This is useful for reflection.
@@ -48,91 +47,56 @@ public extension Sampleable {
 }
 
 extension Sampleable {
-	public static func genericObjectOpenAPINode() throws -> JSONNode {
-		let mirror = Mirror(reflecting: Self.sample)
-		let properties: [(String, JSONNode)] = try mirror.children.compactMap { child in
+	public static func samples<S1: Sampleable>(using s1: S1.Type, with constructor: (S1) -> Self) -> [Self] {
+		return S1.samples.map(constructor)
+	}
 
-			// see if we can enumerate the possible values
-			let maybeAllCases: [AnyCodable]? = {
-				switch type(of: child.value) {
-				case let valType as AnyJSONCaseIterable.Type:
-					return valType.allCases
-				case let valType as AnyWrappedJSONCaseIterable.Type:
-					return valType.allCases
-				default:
-					return nil
-				}
-			}()
+	public static func samples<S1: Sampleable, S2: Sampleable>(using s1: S1.Type, _ s2: S2.Type, with constructor: (S1, S2) -> Self) -> [Self] {
+		return zip(S1.samples, S2.samples).map(constructor)
+	}
 
-			// try to snag an OpenAPI Node
-			let maybeOpenAPINode: JSONNode? = try {
-				switch type(of: child.value) {
-				case let valType as OpenAPINodeType.Type:
-					return try valType.openAPINode()
+	public static func samples<S1: Sampleable, S2: Sampleable, S3: Sampleable>(using s1: S1.Type, _ s2: S2.Type, _ s3: S3.Type, with constructor: (S1, S2, S3) -> Self) -> [Self] {
+		return zip3(S1.samples, S2.samples, S3.samples).map(constructor)
+	}
 
-				case let valType as RawOpenAPINodeType.Type:
-					return try valType.rawOpenAPINode()
+	public static func samples<S1: Sampleable, S2: Sampleable, S3: Sampleable, S4: Sampleable>(using s1: S1.Type, _ s2: S2.Type, _ s3: S3.Type, _ s4: S4.Type, with constructor: (S1, S2, S3, S4) -> Self) -> [Self] {
+		return zip4(S1.samples, S2.samples, S3.samples, S4.samples).map(constructor)
+	}
 
-				case let valType as WrappedRawOpenAPIType.Type:
-					return try valType.wrappedOpenAPINode()
+	public static func samples<S1: Sampleable, S2: Sampleable, S3: Sampleable, S4: Sampleable, S5: Sampleable>(using s1: S1.Type, _ s2: S2.Type, _ s3: S3.Type, _ s4: S4.Type, _ s5: S5.Type, with constructor: (S1, S2, S3, S4, S5) -> Self) -> [Self] {
+		return zip5(S1.samples, S2.samples, S3.samples, S4.samples, S5.samples).map(constructor)
+	}
 
-				case let valType as DoubleWrappedRawOpenAPIType.Type:
-					return try valType.wrappedOpenAPINode()
+	public static func samples<S1: Sampleable, S2: Sampleable, S3: Sampleable, S4: Sampleable, S5: Sampleable, S6: Sampleable>(using s1: S1.Type, _ s2: S2.Type, _ s3: S3.Type, _ s4: S4.Type, _ s5: S5.Type, _ s6: S6.Type, with constructor: (S1, S2, S3, S4, S5, S6) -> Self) -> [Self] {
+		// the compiler craps out at zip6. breaking it down makes the difference.
+		let firstZip = zip3(S1.samples, S2.samples, S3.samples)
+		let secondZip = zip3(S4.samples, S5.samples, S6.samples)
+		return zip(firstZip, secondZip).map { arg in (arg.0.0, arg.0.1, arg.0.2, arg.1.0, arg.1.1, arg.1.2) }.map(constructor)
+	}
 
-				default:
-					return nil
-				}
-			}()
+	public static func samples<S1: Sampleable, S2: Sampleable, S3: Sampleable, S4: Sampleable, S5: Sampleable, S6: Sampleable, S7: Sampleable>(using s1: S1.Type, _ s2: S2.Type, _ s3: S3.Type, _ s4: S4.Type, _ s5: S5.Type, _ s6: S6.Type, _ s7: S7.Type, with constructor: (S1, S2, S3, S4, S5, S6, S7) -> Self) -> [Self] {
+		// the compiler craps out at zip6. breaking it down makes the difference.
+		let firstZip = zip3(S1.samples, S2.samples, S3.samples)
+		let secondZip = zip4(S4.samples, S5.samples, S6.samples, S7.samples)
+		return zip(firstZip, secondZip).map { arg in (arg.0.0, arg.0.1, arg.0.2, arg.1.0, arg.1.1, arg.1.2, arg.1.3) }.map(constructor)
+	}
 
-			// put it all together
-			let newNode: JSONNode?
-			if let allCases = maybeAllCases,
-				let openAPINode = maybeOpenAPINode {
-				newNode = try openAPINode.with(allowedValues: allCases)
-			} else {
-				newNode = maybeOpenAPINode
-			}
+	public static func samples<S1: Sampleable, S2: Sampleable, S3: Sampleable, S4: Sampleable, S5: Sampleable, S6: Sampleable, S7: Sampleable, S8: Sampleable>(using s1: S1.Type, _ s2: S2.Type, _ s3: S3.Type, _ s4: S4.Type, _ s5: S5.Type, _ s6: S6.Type, _ s7: S7.Type, _ s8: S8.Type, with constructor: (S1, S2, S3, S4, S5, S6, S7, S8) -> Self) -> [Self] {
+		// the compiler craps out at zip6. breaking it down makes the difference.
+		let firstZip = zip4(S1.samples, S2.samples, S3.samples, S4.samples)
+		let secondZip = zip4(S5.samples, S6.samples, S7.samples, S8.samples)
+		return zip(firstZip, secondZip).map { arg in (arg.0.0, arg.0.1, arg.0.2, arg.0.3, arg.1.0, arg.1.1, arg.1.2, arg.1.3) }.map(constructor)
+	}
 
-			return zip(child.label, newNode) { ($0, $1) }
-		}
+	@inlinable static func zip3<A: Sequence, B: Sequence, C: Sequence>(_ a: A, _ b: B, _ c: C) -> [(A.Element, B.Element, C.Element)] {
+		return zip(a, zip(b, c)).map { arg in (arg.0, arg.1.0, arg.1.1) }
+	}
 
-		// There should not be any duplication of keys since these are
-		// property names, but rather than risk runtime exception, we just
-		// fail to the newer value arbitrarily
-		let propertiesDict = Dictionary(properties) { _, value2 in value2 }
+	@inlinable static func zip4<A: Sequence, B: Sequence, C: Sequence, D: Sequence>(_ a: A, _ b: B, _ c: C, _ d: D) -> [(A.Element, B.Element, C.Element, D.Element)] {
+		return zip(a, zip(b, zip(c, d))).map { arg in (arg.0, arg.1.0, arg.1.1.0, arg.1.1.1) }
+	}
 
-		return .object(.init(format: .generic,
-							 required: true),
-					   .init(properties: propertiesDict))
-	}
-}
-
-extension NoAttributes: Sampleable {
-	public static var sample: NoAttributes {
-		return .none
-	}
-}
-
-extension NoRelationships: Sampleable {
-	public static var sample: NoRelationships {
-		return .none
-	}
-}
-
-extension NoMetadata: Sampleable {
-	public static var sample: NoMetadata {
-		return .none
-	}
-}
-
-extension NoLinks: Sampleable {
-	public static var sample: NoLinks {
-		return .none
-	}
-}
-
-extension UnknownJSONAPIError: Sampleable {
-	public static var sample: UnknownJSONAPIError {
-		return .unknownError
+	@inlinable static func zip5<A: Sequence, B: Sequence, C: Sequence, D: Sequence, E: Sequence>(_ a: A, _ b: B, _ c: C, _ d: D, _ e: E) -> [(A.Element, B.Element, C.Element, D.Element, E.Element)] {
+		return zip(a, zip(b, zip(c, zip(d, e)))).map { arg in (arg.0, arg.1.0, arg.1.1.0, arg.1.1.1.0, arg.1.1.1.1) }
 	}
 }

Tests/JSONAPIOpenAPITests/JSONAPIAttributeOpenAPITests.swift

@@ -8,6 +8,7 @@
 import XCTest
 import JSONAPI
 import JSONAPIOpenAPI
+import SwiftCheck
 import AnyCodable
 
 class JSONAPIAttributeOpenAPITests: XCTestCase {
@@ -504,6 +505,379 @@ extension JSONAPIAttributeOpenAPITests {
 	}
 }
 
+// MARK: - Date
+extension JSONAPIAttributeOpenAPITests {
+	func test_DateStringAttribute() {
+		// TEST:
+		// Encoder is set to use
+		// formatter with date
+		// with no time.
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .none
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = Attribute<Date>.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNotNil(node)
+
+		XCTAssertTrue(node?.required ?? false)
+		XCTAssertEqual(node?.jsonTypeFormat, .string(.date))
+
+		guard case .string(let contextA, let stringContext)? = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .date,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(stringContext, .init())
+	}
+
+	func test_DateStringAttribute_Sampleable() {
+		// TEST:
+		// Encoder is set to use
+		// formatter with date
+		// with no time.
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .none
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = try! Attribute<Date>.genericOpenAPINode(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .string(.date))
+
+		guard case .string(let contextA, let stringContext) = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .date,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(stringContext, .init())
+	}
+
+	func test_DateTimeStringAttribute() {
+		// TEST:
+		// Encoder is set to use
+		// formatter with date
+		// with time.
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .short
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = Attribute<Date>.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNotNil(node)
+
+		XCTAssertTrue(node?.required ?? false)
+		XCTAssertEqual(node?.jsonTypeFormat, .string(.dateTime))
+
+		guard case .string(let contextA, let stringContext)? = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .dateTime,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(stringContext, .init())
+	}
+
+	func test_DateTimeStringAttribute_Sampleable() {
+		// TEST:
+		// Encoder is set to use
+		// formatter with date
+		// with time.
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .short
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = try! Attribute<Date>.genericOpenAPINode(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .string(.dateTime))
+
+		guard case .string(let contextA, let stringContext) = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .dateTime,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(stringContext, .init())
+	}
+
+	func test_8601DateStringAttribute() {
+		if #available(OSX 10.12, *) {
+			// TEST:
+			// Encoder is set to use
+			// iso8601 date format
+
+			let encoder = JSONEncoder()
+			encoder.outputFormatting = .prettyPrinted
+			encoder.dateEncodingStrategy = .iso8601
+
+			let node = Attribute<Date>.dateOpenAPINodeGuess(using: encoder)
+
+			XCTAssertNotNil(node)
+
+			XCTAssertTrue(node?.required ?? false)
+			XCTAssertEqual(node?.jsonTypeFormat, .string(.dateTime))
+
+			guard case .string(let contextA, let stringContext)? = node else {
+				XCTFail("Expected string Node")
+				return
+			}
+
+			XCTAssertEqual(contextA, .init(format: .dateTime,
+										   required: true,
+										   nullable: false,
+										   allowedValues: nil))
+
+			XCTAssertEqual(stringContext, .init())
+		}
+	}
+
+	func test_8601DateStringAttribute_Sampleable() {
+		if #available(OSX 10.12, *) {
+			// TEST:
+			// Encoder is set to use
+			// iso8601 date format
+
+			let encoder = JSONEncoder()
+			encoder.outputFormatting = .prettyPrinted
+			encoder.dateEncodingStrategy = .iso8601
+
+			let node = try! Attribute<Date>.genericOpenAPINode(using: encoder)
+
+			XCTAssertTrue(node.required)
+			XCTAssertEqual(node.jsonTypeFormat, .string(.dateTime))
+
+			guard case .string(let contextA, let stringContext) = node else {
+				XCTFail("Expected string Node")
+				return
+			}
+
+			XCTAssertEqual(contextA, .init(format: .dateTime,
+										   required: true,
+										   nullable: false,
+										   allowedValues: nil))
+
+			XCTAssertEqual(stringContext, .init())
+		}
+	}
+
+	func test_DateNumberAttribute() {
+		// TEST:
+		// Encoder is set to use
+		// seconds since 1970 as
+		// date format
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .secondsSince1970
+
+		let node = Attribute<Date>.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNotNil(node)
+
+		XCTAssertTrue(node?.required ?? false)
+		XCTAssertEqual(node?.jsonTypeFormat, .number(.double))
+
+		guard case .number(let contextA, let numberContext)? = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .double,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(numberContext, .init())
+	}
+
+	func test_DateNumberAttribute_Sampleable() {
+		// TEST:
+		// Encoder is set to use
+		// seconds since 1970 as
+		// date format
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .secondsSince1970
+
+		let node = try! Attribute<Date>.genericOpenAPINode(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .number(.double))
+
+		guard case .number(let contextA, let numberContext) = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .double,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(numberContext, .init())
+	}
+
+	func test_DateDeferredAttribute() {
+		// TEST:
+		// Encoder is set to use
+		// Date default encoding
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .deferredToDate
+
+		let node = Attribute<Date>.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNil(node)
+	}
+
+	func test_DateDeferredAttribute_Sampleable() {
+		// TEST:
+		// Encoder is set to use
+		// Date default encoding
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .deferredToDate
+
+		let node = try! Attribute<Date>.genericOpenAPINode(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .number(.double))
+
+		guard case .number(let contextA, let numberContext) = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .double,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(numberContext, .init())
+	}
+
+	func test_NullableDateAttribute() {
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .secondsSince1970
+
+		let node = Attribute<Date?>.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNotNil(node)
+
+		XCTAssertTrue(node?.required ?? false)
+		XCTAssertEqual(node?.jsonTypeFormat, .number(.double))
+
+		guard case .number(let contextA, let numberContext)? = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .double,
+									   required: true,
+									   nullable: true,
+									   allowedValues: nil))
+
+		XCTAssertEqual(numberContext, .init())
+	}
+
+	func test_OptionalDateAttribute() {
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .secondsSince1970
+
+		let node = Attribute<Date>?.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNotNil(node)
+
+		XCTAssertFalse(node?.required ?? true)
+		XCTAssertEqual(node?.jsonTypeFormat, .number(.double))
+
+		guard case .number(let contextA, let numberContext)? = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .double,
+									   required: false,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(numberContext, .init())
+	}
+
+	func test_OptionalNullableDateAttribute() {
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .secondsSince1970
+
+		let node = Attribute<Date?>?.dateOpenAPINodeGuess(using: encoder)
+
+		XCTAssertNotNil(node)
+
+		XCTAssertFalse(node?.required ?? true)
+		XCTAssertEqual(node?.jsonTypeFormat, .number(.double))
+
+		guard case .number(let contextA, let numberContext)? = node else {
+			XCTFail("Expected string Node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .double,
+									   required: false,
+									   nullable: true,
+									   allowedValues: nil))
+
+		XCTAssertEqual(numberContext, .init())
+	}
+}
+
 // MARK: - Test Types
 extension JSONAPIAttributeOpenAPITests {
 	enum EnumAttribute: String, Codable, CaseIterable {
@@ -511,3 +885,9 @@ extension JSONAPIAttributeOpenAPITests {
 		case two
 	}
 }
+
+extension Date: SampleableOpenAPIType {
+	public static var sample: Date {
+		return TimeInterval.arbitrary.map { Date(timeIntervalSince1970: $0) }.generate
+	}
+}

Tests/JSONAPIOpenAPITests/JSONAPIDocumentOpenAPITests.swift

@@ -6,17 +6,307 @@
 //
 
 import XCTest
+import SwiftCheck
 import JSONAPI
 import JSONAPIOpenAPI
 
 class JSONAPIDocumentOpenAPITests: XCTestCase {
 	func test_SingleResourceDocument() {
-		let node = try! SingleEntityDocument.openAPINode()
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .none
+		dateFormatter.locale = Locale(identifier: "en_US")
 
 		let encoder = JSONEncoder()
 		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
 
-		print(String(data: try! encoder.encode(node), encoding: .utf8)!)
+		let node = try! SingleEntityDocument.openAPINodeWithExample(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
+
+		guard case let .object(contextA, objectContext1) = node else {
+			XCTFail("Expected JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertNotNil(contextA.example)
+		XCTAssertFalse(contextA.nullable)
+		XCTAssertEqual(contextA.format, .generic)
+		XCTAssertTrue(contextA.required)
+
+		XCTAssertEqual(objectContext1.minProperties, 1)
+		XCTAssertEqual(Set(objectContext1.requiredProperties), Set(["data"]))
+		XCTAssertEqual(Set(objectContext1.properties.keys), Set(["data"]))
+
+		guard case let .object(contextB, objectContext2)? = objectContext1.properties["data"] else {
+			XCTFail("Expected Data field of JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextB.nullable)
+		XCTAssertEqual(contextB.format, .generic)
+		XCTAssertTrue(contextB.required)
+
+		XCTAssertEqual(objectContext2.minProperties, 3)
+		XCTAssertEqual(Set(objectContext2.requiredProperties), Set(["id", "attributes", "type"]))
+		XCTAssertEqual(Set(objectContext2.properties.keys), Set(["id", "attributes", "type"]))
+
+		XCTAssertEqual(objectContext2.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test")]),
+									   .init()))
+	}
+
+	func test_ManyResourceDocument() {
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .none
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = try! ManyEntityDocument.openAPINodeWithExample(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
+
+		guard case let .object(contextA, objectContext1) = node else {
+			XCTFail("Expected JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertNotNil(contextA.example)
+		XCTAssertFalse(contextA.nullable)
+		XCTAssertEqual(contextA.format, .generic)
+		XCTAssertTrue(contextA.required)
+
+		XCTAssertEqual(objectContext1.minProperties, 1)
+		XCTAssertEqual(Set(objectContext1.requiredProperties), Set(["data"]))
+		XCTAssertEqual(Set(objectContext1.properties.keys), Set(["data"]))
+
+		guard case let .array(contextB, arrayContext)? = objectContext1.properties["data"] else {
+			XCTFail("Expected Data field of JSON Document to be an Array Node")
+			return
+		}
+
+		XCTAssertFalse(contextB.nullable)
+		XCTAssertEqual(contextB.format, .generic)
+		XCTAssertTrue(contextB.required)
+
+		XCTAssertFalse(arrayContext.uniqueItems)
+		XCTAssertEqual(arrayContext.minItems, 0)
+
+		guard case let .object(contextC, objectContext2) = arrayContext.items else {
+			XCTFail("Expected Items of Array under Data to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextC.nullable)
+		XCTAssertEqual(contextC.format, .generic)
+		XCTAssertTrue(contextC.required)
+
+		XCTAssertEqual(objectContext2.minProperties, 3)
+		XCTAssertEqual(Set(objectContext2.requiredProperties), Set(["id", "attributes", "type"]))
+		XCTAssertEqual(Set(objectContext2.properties.keys), Set(["id", "attributes", "type"]))
+
+		XCTAssertEqual(objectContext2.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test")]),
+									   .init()))
+	}
+
+	func test_DocumentWithOneIncludeType() {
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .none
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = try! DocumentWithIncludes.openAPINodeWithExample(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
+
+		guard case let .object(contextA, objectContext1) = node else {
+			XCTFail("Expected JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertNotNil(contextA.example)
+		XCTAssertFalse(contextA.nullable)
+		XCTAssertEqual(contextA.format, .generic)
+		XCTAssertTrue(contextA.required)
+
+		XCTAssertEqual(objectContext1.minProperties, 2)
+		XCTAssertEqual(Set(objectContext1.requiredProperties), Set(["data", "included"]))
+		XCTAssertEqual(Set(objectContext1.properties.keys), Set(["data", "included"]))
+
+		guard case let .object(contextB, objectContext2)? = objectContext1.properties["data"] else {
+			XCTFail("Expected Data field of JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextB.nullable)
+		XCTAssertEqual(contextB.format, .generic)
+		XCTAssertTrue(contextB.required)
+
+		XCTAssertEqual(objectContext2.minProperties, 3)
+		XCTAssertEqual(Set(objectContext2.requiredProperties), Set(["id", "attributes", "type"]))
+		XCTAssertEqual(Set(objectContext2.properties.keys), Set(["id", "attributes", "type"]))
+
+		XCTAssertEqual(objectContext2.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test")]),
+									   .init()))
+
+		guard case let .array(contextC, arrayContext)? = objectContext1.properties["included"] else {
+			XCTFail("Expected Includes field of JSON Document to be an Array Node")
+			return
+		}
+
+		XCTAssertFalse(contextC.nullable)
+		XCTAssertEqual(contextC.format, .generic)
+		XCTAssertTrue(contextC.required)
+
+		XCTAssertTrue(arrayContext.uniqueItems)
+		XCTAssertEqual(arrayContext.minItems, 0)
+
+		guard case let .object(contextD, objectContext3) = arrayContext.items else {
+			XCTFail("Expected Items of Array under Data to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextD.nullable)
+		XCTAssertEqual(contextD.format, .generic)
+		XCTAssertTrue(contextD.required)
+
+		XCTAssertEqual(objectContext3.minProperties, 3)
+		XCTAssertEqual(Set(objectContext3.requiredProperties), Set(["id", "attributes", "type"]))
+		XCTAssertEqual(Set(objectContext3.properties.keys), Set(["id", "attributes", "type"]))
+
+		XCTAssertEqual(objectContext3.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test")]),
+									   .init()))
+	}
+
+	func test_DocumentWithTwoIncludeTypes() {
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .none
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = try! DocumentWithMultipleTypesOfIncludes.openAPINodeWithExample(using: encoder)
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
+
+		guard case let .object(contextA, objectContext1) = node else {
+			XCTFail("Expected JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertNotNil(contextA.example)
+		XCTAssertFalse(contextA.nullable)
+		XCTAssertEqual(contextA.format, .generic)
+		XCTAssertTrue(contextA.required)
+
+		XCTAssertEqual(objectContext1.minProperties, 2)
+		XCTAssertEqual(Set(objectContext1.requiredProperties), Set(["data", "included"]))
+		XCTAssertEqual(Set(objectContext1.properties.keys), Set(["data", "included"]))
+
+		guard case let .object(contextB, objectContext2)? = objectContext1.properties["data"] else {
+			XCTFail("Expected Data field of JSON Document to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextB.nullable)
+		XCTAssertEqual(contextB.format, .generic)
+		XCTAssertTrue(contextB.required)
+
+		XCTAssertEqual(objectContext2.minProperties, 3)
+		XCTAssertEqual(Set(objectContext2.requiredProperties), Set(["id", "attributes", "type"]))
+		XCTAssertEqual(Set(objectContext2.properties.keys), Set(["id", "attributes", "type"]))
+
+		XCTAssertEqual(objectContext2.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test")]),
+									   .init()))
+
+		guard case let .array(contextC, arrayContext)? = objectContext1.properties["included"] else {
+			XCTFail("Expected Includes field of JSON Document to be an Array Node")
+			return
+		}
+
+		XCTAssertFalse(contextC.nullable)
+		XCTAssertEqual(contextC.format, .generic)
+		XCTAssertTrue(contextC.required)
+
+		XCTAssertTrue(arrayContext.uniqueItems)
+		XCTAssertEqual(arrayContext.minItems, 0)
+
+		guard case let .one(of: includeNodes) = arrayContext.items else {
+			XCTFail("Expected Included to contain multiple types of items.")
+			return
+		}
+
+		XCTAssertEqual(includeNodes.count, 2)
+
+		guard case let .object(contextD, objectContext3) = includeNodes[0] else {
+			XCTFail("Expected Items of OneOf under Array under Data to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextD.nullable)
+		XCTAssertEqual(contextD.format, .generic)
+		XCTAssertTrue(contextD.required)
+
+		XCTAssertEqual(objectContext3.minProperties, 3)
+		XCTAssertEqual(Set(objectContext3.requiredProperties), Set(["id", "attributes", "type"]))
+		XCTAssertEqual(Set(objectContext3.properties.keys), Set(["id", "attributes", "type"]))
+
+		XCTAssertEqual(objectContext3.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test")]),
+									   .init()))
+
+		guard case let .object(contextE, objectContext4) = includeNodes[1] else {
+			XCTFail("Expected Items of OneOf under Array under Data to be an Object Node")
+			return
+		}
+
+		XCTAssertFalse(contextE.nullable)
+		XCTAssertEqual(contextE.format, .generic)
+		XCTAssertTrue(contextE.required)
+
+		XCTAssertEqual(objectContext4.minProperties, 2)
+		XCTAssertEqual(Set(objectContext4.requiredProperties), Set(["id", "type"]))
+		XCTAssertEqual(Set(objectContext4.properties.keys), Set(["id", "type"]))
+
+		XCTAssertEqual(objectContext4.properties["type"],
+					   JSONNode.string(.init(format: .generic,
+											 required: true,
+											 allowedValues: [.init("test2")]),
+									   .init()))
 	}
 }
 
@@ -27,9 +317,11 @@ extension JSONAPIDocumentOpenAPITests {
 
 		struct Attributes: JSONAPI.Attributes, Sampleable {
 			let name: Attribute<String>
+			let date: Attribute<Date>
 
 			static var sample: Attributes {
-				return .init(name: "hello world")
+				return .init(name: "hello world",
+							 date: .init(value: Date()))
 			}
 		}
 
@@ -39,4 +331,46 @@ extension JSONAPIDocumentOpenAPITests {
 	typealias TestEntity = BasicEntity<TestEntityDescription>
 
 	typealias SingleEntityDocument = Document<SingleResourceBody<TestEntity>, NoMetadata, NoLinks, NoIncludes, NoAPIDescription, UnknownJSONAPIError>
+
+	typealias ManyEntityDocument = Document<ManyResourceBody<TestEntity>, NoMetadata, NoLinks, NoIncludes, NoAPIDescription, UnknownJSONAPIError>
+
+	typealias DocumentWithIncludes = Document<SingleResourceBody<TestEntity>, NoMetadata, NoLinks, Include1<TestEntity>, NoAPIDescription, UnknownJSONAPIError>
+
+	enum TestEntityDescription2: EntityDescription {
+		static var jsonType: String { return "test2" }
+
+		typealias Attributes = NoAttributes
+
+		typealias Relationships = NoRelationships
+	}
+
+	typealias TestEntity2 = BasicEntity<TestEntityDescription2>
+
+	typealias DocumentWithMultipleTypesOfIncludes = Document<SingleResourceBody<TestEntity>, NoMetadata, NoLinks, Include2<TestEntity, TestEntity2>, NoAPIDescription, UnknownJSONAPIError>
+}
+
+extension Id: Sampleable where RawType == String {
+	public static var sample: Id<RawType, IdentifiableType> {
+		return .init(rawValue: String.arbitrary.generate)
+	}
+}
+
+extension JSONAPI.Entity: Sampleable where Description.Attributes: Sampleable, Description.Relationships: Sampleable, MetaType: Sampleable, LinksType: Sampleable, EntityRawIdType == String {
+	public static var sample: JSONAPI.Entity<Description, MetaType, LinksType, EntityRawIdType> {
+		return JSONAPI.Entity(id: .sample,
+							  attributes: .sample,
+							  relationships: .sample,
+							  meta: .sample,
+							  links: .sample)
+	}
+}
+
+extension Document: Sampleable where PrimaryResourceBody: Sampleable, MetaType: Sampleable, LinksType: Sampleable, IncludeType: Sampleable, APIDescription: Sampleable, Error: Sampleable {
+	public static var sample: Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error> {
+		return Document(apiDescription: .sample,
+						body: .sample,
+						includes: .sample,
+						meta: .sample,
+						links: .sample)
+	}
 }

Tests/JSONAPIOpenAPITests/JSONAPIEntityOpenAPITests.swift

@@ -12,7 +12,7 @@ import AnyCodable
 
 class JSONAPIEntityOpenAPITests: XCTestCase {
 	func test_EmptyEntity() {
-		let node = try! TestType1.openAPINode()
+		let node = try! TestType1.openAPINode(using: JSONEncoder())
 
 		XCTAssertTrue(node.required)
 		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
@@ -39,8 +39,42 @@ class JSONAPIEntityOpenAPITests: XCTestCase {
 																.init()))
 	}
 
+	func test_UnidentifiedEmptyEntity() {
+		let node = try! UnidentifiedTestType1.openAPINode(using: JSONEncoder())
+
+		XCTAssertTrue(node.required)
+		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
+
+		guard case let .object(contextA, objectContext1) = node else {
+			XCTFail("Expected Object node")
+			return
+		}
+
+		XCTAssertEqual(contextA, .init(format: .generic,
+									   required: true,
+									   nullable: false,
+									   allowedValues: nil))
+
+		XCTAssertEqual(objectContext1.minProperties, 1)
+		XCTAssertEqual(Set(objectContext1.requiredProperties), Set(["type"]))
+		XCTAssertEqual(Set(objectContext1.properties.keys), Set(["type"]))
+		XCTAssertEqual(objectContext1.properties["type"], .string(.init(format: .generic,
+																		required: true,
+																		allowedValues: [.init(TestType1.jsonType)]),
+																  .init()))
+	}
+
 	func test_AttributesEntity() {
-		let node = try! TestType2.openAPINode()
+
+		let dateFormatter = DateFormatter()
+		dateFormatter.dateStyle = .medium
+		dateFormatter.timeStyle = .short
+		dateFormatter.locale = Locale(identifier: "en_US")
+
+		let encoder = JSONEncoder()
+		encoder.dateEncodingStrategy = .formatted(dateFormatter)
+
+		let node = try! TestType2.openAPINode(using: encoder)
 
 		XCTAssertTrue(node.required)
 		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
@@ -83,9 +117,9 @@ class JSONAPIEntityOpenAPITests: XCTestCase {
 									   nullable: false,
 									   allowedValues: nil))
 
-		XCTAssertEqual(attributesContext.minProperties, 3)
-		XCTAssertEqual(Set(attributesContext.requiredProperties), Set(["stringProperty", "enumProperty", "nullableProperty"]))
-		XCTAssertEqual(Set(attributesContext.properties.keys), Set(["stringProperty", "enumProperty", "optionalProperty", "nullableProperty", "nullableOptionalProperty"]))
+		XCTAssertEqual(attributesContext.minProperties, 4)
+		XCTAssertEqual(Set(attributesContext.requiredProperties), Set(["stringProperty", "enumProperty", "dateProperty", "nullableProperty"]))
+		XCTAssertEqual(Set(attributesContext.properties.keys), Set(["stringProperty", "enumProperty", "dateProperty", "optionalProperty", "nullableProperty", "nullableOptionalProperty"]))
 
 		XCTAssertEqual(attributesContext.properties["stringProperty"],
 					   .string(.init(format: .generic,
@@ -99,6 +133,13 @@ class JSONAPIEntityOpenAPITests: XCTestCase {
 									 allowedValues: ["one", "two"].map(AnyCodable.init)),
 							   .init()))
 
+		XCTAssertEqual(attributesContext.properties["dateProperty"],
+					   .string(.init(format: .dateTime,
+									 required: true,
+									 nullable: false,
+									 allowedValues: nil),
+							   .init()))
+
 		XCTAssertEqual(attributesContext.properties["optionalProperty"],
 					   .string(.init(format: .generic,
 									 required: false,
@@ -122,7 +163,7 @@ class JSONAPIEntityOpenAPITests: XCTestCase {
 	}
 
 	func test_RelationshipsEntity() {
-		let node = try! TestType3.openAPINode()
+		let node = try! TestType3.openAPINode(using: JSONEncoder())
 
 		XCTAssertTrue(node.required)
 		XCTAssertEqual(node.jsonTypeFormat, .object(.generic))
@@ -256,6 +297,7 @@ extension JSONAPIEntityOpenAPITests {
 	}
 
 	typealias TestType1 = BasicEntity<TestType1Description>
+	typealias UnidentifiedTestType1 = JSONAPI.Entity<TestType1Description, NoMetadata, NoLinks, Unidentified>
 
 	enum TestType2Description: EntityDescription {
 		public static var jsonType: String { return "test2" }
@@ -268,6 +310,7 @@ extension JSONAPIEntityOpenAPITests {
 		public struct Attributes: JSONAPI.Attributes, Sampleable {
 			let stringProperty: Attribute<String>
 			let enumProperty: Attribute<EnumType>
+			let dateProperty: Attribute<Date>
 			let optionalProperty: Attribute<String>?
 			let nullableProperty: Attribute<String?>
 			let nullableOptionalProperty: Attribute<String?>?
@@ -278,6 +321,7 @@ extension JSONAPIEntityOpenAPITests {
 			public static var sample: Attributes {
 				return Attributes(stringProperty: .init(value: "hello"),
 								  enumProperty: .init(value: .one),
+								  dateProperty: .init(value: Date()),
 								  optionalProperty: nil,
 								  nullableProperty: .init(value: nil),
 								  nullableOptionalProperty: nil)

Tests/JSONAPIOpenAPITests/OpenAPI/OpenAPITests.swift

@@ -0,0 +1,52 @@
+//
+//  OpenAPITests.swift
+//  JSONAPIOpenAPITests
+//
+//  Created by Mathew Polzin on 1/25/19.
+//
+
+import XCTest
+import JSONAPI
+import JSONAPIOpenAPI
+
+class OpenAPITests: XCTestCase {
+
+	func test_placeholder() {
+
+		let schemaInfo = OpenAPISchema.Info(title: "Cool API", version: "0.1.0")
+
+		let personResponse = OpenAPIResponse(description: "Successfully created a Person",
+											 content: [
+												.json: .init(schema: .init(JSONReference.node(.init(type: \.schemas, selector: "person"))))
+			])
+
+		let schemaPaths: [OpenAPISchema.PathComponents: OpenAPIPathItem] = [
+			.init(["api","people"]):
+			.operations(
+				.init(parameters: [],
+					  post: OpenAPIPathItem.PathProperties.Operation(
+						summary: "",
+						operationId: "createPerson",
+						parameters: [],
+						responses: [
+							.status(code: 200): .init(personResponse)
+						]
+					)
+				)
+			)
+		]
+
+		let schemaComponents = OpenAPIComponents(schemas: ["person": .reference(.file("person.json"))],
+												 parameters: [:])
+
+		let openAPISchema = OpenAPISchema(info: schemaInfo,
+										  paths: schemaPaths,
+										  components: schemaComponents)
+
+		let encoder = JSONEncoder()
+		encoder.outputFormatting = .prettyPrinted
+
+		print(String(data: try! encoder.encode(openAPISchema), encoding: .utf8)!)
+	}
+
+}