Add support for RequestBody on an OpenAPI Operation.

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

@@ -0,0 +1,46 @@
+//: [Previous](@previous)
+
+import Foundation
+import JSONAPI
+import JSONAPIOpenAPI
+import Poly
+
+// print Entity Schema
+let encoder = JSONEncoder()
+encoder.outputFormatting = .prettyPrinted
+
+let personSchemaData = try? encoder.encode(Person.openAPINode())
+
+print("Person Schema")
+print("====")
+print(personSchemaData.map { String(data: $0, encoding: .utf8)! } ?? "Schema Construction Failed")
+print("====")
+
+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(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)!)

JSONAPI.playground/Pages/Test Library.xcplaygroundpage/Contents.swift

@@ -2,7 +2,7 @@
 
 import Foundation
 import JSONAPI
-import JSONAPITestLib
+import JSONAPITesting
 
 /*******
 
@@ -11,12 +11,12 @@ Please enjoy these examples, but allow me the forced casting and the lack of err
 ********/
 
 // MARK: - Literal Expressibility
-// The JSONAPITestLib provides literal expressibility for key types to
+// The JSONAPITesting framework provides literal expressibility for key types to
 // make creating tests easier
 let dog = Dog(id: "1234", attributes: Dog.Attributes(name: "Buddy"), relationships: Dog.Relationships(owner: nil), meta: .none, links: .none)
 
 // MARK: - JSON API structure checking
-// The JSONAPITestLib provides a `check` function for each Entity type
+// The JSONAPITesting framework provides a `check` function for each Entity type
 // that uses reflection to catch mistakes that are not forbidden by
 // Swift's type system but will result in unexpected results when
 // encoding/decoding. It is a good idea to add a `check` to each of

JSONAPI.playground/Pages/Usage.xcplaygroundpage/Contents.swift

@@ -11,8 +11,6 @@ Please enjoy these examples, but allow me the forced casting and the lack of err
 // MARK: - Create a request or response body with one Dog in it
 let dogFromCode = try! Dog(name: "Buddy", owner: nil)
 
-typealias SingleDogDocument = JSONAPI.Document<SingleResourceBody<Dog>, NoMetadata, NoLinks, NoIncludes, NoAPIDescription, UnknownJSONAPIError>
-
 let singleDogDocument = SingleDogDocument(apiDescription: .none, body: .init(entity: dogFromCode), includes: .none, meta: .none, links: .none)
 
 let singleDogData = try! JSONEncoder().encode(singleDogDocument)
@@ -34,8 +32,6 @@ let dogs = try! [Dog(name: "Buddy", owner: personIds[0]), Dog(name: "Joy", owner
 let houses = [House(attributes: .none, relationships: .none, meta: .none, links: .none), House(attributes: .none, relationships: .none, meta: .none, links: .none)]
 let people = try! [Person(id: personIds[0], name: ["Gary", "Doe"], favoriteColor: "Orange-Red", friends: [], dogs: [dogs[0], dogs[1]], home: houses[0]), Person(id: personIds[1], name: ["Elise", "Joy"], favoriteColor: "Red", friends: [], dogs: [dogs[2]], home: houses[1])]
 
-typealias BatchPeopleDocument = JSONAPI.Document<ManyResourceBody<Person>, NoMetadata, NoLinks, Include2<Dog, House>, NoAPIDescription, UnknownJSONAPIError>
-
 let includes = dogs.map { BatchPeopleDocument.Include($0) } + houses.map { BatchPeopleDocument.Include($0) }
 let batchPeopleDocument = BatchPeopleDocument(apiDescription: .none, body: .init(entities: people), includes: .init(values: includes), meta: .none, links: .none)
 let batchPeopleData = try! JSONEncoder().encode(batchPeopleDocument)

JSONAPI.playground/Sources/Entities.swift

@@ -139,4 +139,6 @@ public enum HouseDescription: EntityDescription {
 
 public typealias House = ExampleEntity<HouseDescription>
 
+public typealias SingleDogDocument = JSONAPI.Document<SingleResourceBody<Dog>, NoMetadata, NoLinks, NoIncludes, NoAPIDescription, UnknownJSONAPIError>
 
+public typealias BatchPeopleDocument = JSONAPI.Document<ManyResourceBody<Person>, NoMetadata, NoLinks, Include2<Dog, House>, NoAPIDescription, UnknownJSONAPIError>

JSONAPI.playground/Sources/OpenAPISupport.swift

@@ -0,0 +1,71 @@
+import Foundation
+import JSONAPI
+import JSONAPITesting // for the convenience of literal initialization
+import JSONAPIOpenAPI
+import SwiftCheck
+import JSONAPIArbitrary
+
+extension PersonDescription.Attributes: Arbitrary, Sampleable {
+	public static var arbitrary: Gen<PersonDescription.Attributes> {
+		return Gen.compose { c in
+			return PersonDescription.Attributes(name: c.generate(),
+												favoriteColor: c.generate())
+		}
+	}
+
+	public static var sample: PersonDescription.Attributes {
+		return .init(name: ["Abbie", "Eibba"], favoriteColor: "Blue")
+	}
+}
+
+extension PersonDescription.Relationships: Arbitrary, Sampleable {
+	public static var arbitrary: Gen<PersonDescription.Relationships> {
+		return Gen.compose { c in
+			return PersonDescription.Relationships(friends: c.generate(),
+												   dogs: c.generate(),
+												   home: c.generate())
+		}
+	}
+
+	public static var sample: PersonDescription.Relationships {
+		return .init(friends: ["1", "2"], dogs: ["2"], home: "1")
+	}
+}
+
+extension DogDescription.Attributes: Arbitrary, Sampleable {
+	public static var arbitrary: Gen<DogDescription.Attributes> {
+		return Gen.compose { c in
+			return DogDescription.Attributes(name: c.generate())
+		}
+	}
+
+	public static var sample: DogDescription.Attributes {
+		return DogDescription.Attributes.arbitrary.generate
+	}
+}
+
+extension DogDescription.Relationships: Arbitrary, Sampleable {
+	public static var arbitrary: Gen<DogDescription.Relationships> {
+		return Gen.compose { c in
+			return DogDescription.Relationships(owner: c.generate())
+		}
+	}
+
+	public static var sample: DogDescription.Relationships {
+		return DogDescription.Relationships.arbitrary.generate
+	}
+}
+
+extension Document: Sampleable where PrimaryResourceBody: Arbitrary, IncludeType: Arbitrary, MetaType: Arbitrary, LinksType: Arbitrary, Error: Arbitrary, APIDescription: Arbitrary {
+	public static var sample: Document {
+		return Document.arbitrary.generate
+	}
+
+	public static var successSample: Document? {
+		return Document.arbitraryData.generate
+	}
+
+	public static var failureSample: Document? {
+		return Document.arbitraryErrors.generate
+	}
+}

JSONAPI.playground/contents.xcplayground

@@ -3,5 +3,7 @@
     <pages>
         <page name='Test Library'/>
         <page name='Usage'/>
+        <page name='Full Client &amp; Server Example'/>
+        <page name='Full Document Verbose Generation'/>
     </pages>
 </playground>

LICENSE.txt

@@ -0,0 +1,7 @@
+Copyright 2018 Mathew Polzin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Package.resolved

@@ -1,7 +1,42 @@
 {
   "object": {
     "pins": [
-
+      {
+        "package": "AnyCodable",
+        "repositoryURL": "https://github.com/Flight-School/AnyCodable.git",
+        "state": {
+          "branch": null,
+          "revision": "396ccc3dba5bdee04c1e742e7fab40582861401e",
+          "version": "0.1.0"
+        }
+      },
+      {
+        "package": "FileCheck",
+        "repositoryURL": "https://github.com/llvm-swift/FileCheck.git",
+        "state": {
+          "branch": null,
+          "revision": "89b8480055f9adf8ce2f9ad5e2fac7ac1076242e",
+          "version": "0.0.8"
+        }
+      },
+      {
+        "package": "Poly",
+        "repositoryURL": "https://github.com/mattpolzin/Poly.git",
+        "state": {
+          "branch": null,
+          "revision": "77f45b8963a51c02d71fc4075eba5cff47ff0d07",
+          "version": "1.0.0"
+        }
+      },
+      {
+        "package": "SwiftCheck",
+        "repositoryURL": "https://github.com/typelift/SwiftCheck.git",
+        "state": {
+          "branch": null,
+          "revision": "cf9958085b2ee1643e541e407c3233d1b76c18ff",
+          "version": "0.11.0"
+        }
+      }
     ]
   },
   "version": 1

Package.swift

@@ -10,21 +10,45 @@ let package = Package(
             name: "JSONAPI",
             targets: ["JSONAPI"]),
 		.library(
-			name: "JSONAPITestLib",
-			targets: ["JSONAPITestLib"])
+			name: "JSONAPITesting",
+			targets: ["JSONAPITesting"]),
+		.library(
+			name: "JSONAPIArbitrary",
+			targets: ["JSONAPIArbitrary"]),
+        .library(
+            name: "JSONAPIOpenAPI",
+            targets: ["JSONAPIOpenAPI"])
     ],
     dependencies: [
+		.package(url: "https://github.com/mattpolzin/Poly.git", from: "1.0.0"),
+        .package(url: "https://github.com/Flight-School/AnyCodable.git", from: "0.1.0"),
+		.package(url: "https://github.com/typelift/SwiftCheck.git", from: "0.11.0")
     ],
     targets: [
         .target(
             name: "JSONAPI",
-            dependencies: []),
+            dependencies: ["Poly"]),
 		.target(
-			name: "JSONAPITestLib",
+			name: "JSONAPITesting",
 			dependencies: ["JSONAPI"]),
+		.target(
+			name: "JSONAPIArbitrary",
+			dependencies: ["JSONAPI", "SwiftCheck"]),
+        .target(
+            name: "JSONAPIOpenAPI",
+            dependencies: ["JSONAPI", "AnyCodable", "JSONAPIArbitrary"]),
         .testTarget(
             name: "JSONAPITests",
-            dependencies: ["JSONAPITestLib"])
+            dependencies: ["JSONAPI", "JSONAPITesting"]),
+        .testTarget(
+            name: "JSONAPITestingTests",
+            dependencies: ["JSONAPI", "JSONAPITesting"]),
+		.testTarget(
+			name: "JSONAPIArbitraryTests",
+			dependencies: ["JSONAPI", "SwiftCheck", "JSONAPIArbitrary"]),
+        .testTarget(
+            name: "JSONAPIOpenAPITests",
+            dependencies: ["JSONAPI", "JSONAPIOpenAPI"])
     ],
   	swiftLanguageVersions: [.v4_2]
 )

Sources/JSONAPI/Document/Document.swift

@@ -5,6 +5,8 @@
 //  Created by Mathew Polzin on 11/5/18.
 //
 
+import Poly
+
 public protocol JSONAPIDocument: Codable, Equatable {
 	associatedtype PrimaryResourceBody: JSONAPI.ResourceBody
 	associatedtype MetaType: JSONAPI.Meta

Sources/JSONAPI/Document/Includes.swift

@@ -5,7 +5,9 @@
 //  Created by Mathew Polzin on 11/10/18.
 //
 
-public typealias Include = Poly
+import Poly
+
+public typealias Include = JSONPoly
 
 public struct Includes<I: Include>: Codable, Equatable {
 	public static var none: Includes { return .init(values: []) }

Sources/JSONAPI/Resource/Attribute.swift

@@ -16,7 +16,7 @@ public protocol AttributeType: Codable {
 
 /// A TransformedAttribute takes a Codable type and attempts to turn it into another type.
 public struct TransformedAttribute<RawValue: Codable, Transformer: JSONAPI.Transformer>: AttributeType where Transformer.From == RawValue {
-	let rawValue: RawValue
+	public let rawValue: RawValue
 	
 	public let value: Transformer.To
 	

Sources/JSONAPI/Resource/Entity.swift

@@ -471,6 +471,15 @@ public extension EntityProxy {
 	}
 }
 
+// MARK: Meta-Attribute Access
+public extension EntityProxy {
+	/// Access an attribute requiring a transformation on the RawValue _and_
+	/// a secondary transformation on this entity (self).
+	subscript<T>(_ path: KeyPath<Description.Attributes, (Self) -> T>) -> T {
+		return attributes[keyPath: path](self)
+	}
+}
+
 // MARK: Relationship Access
 public extension EntityProxy {
 	/// Access to an Id of a `ToOneRelationship`.
@@ -513,6 +522,23 @@ public extension EntityProxy {
 	}
 }
 
+// MARK: Meta-Relationship Access
+public extension EntityProxy {
+	/// Access to an Id of a `ToOneRelationship`.
+	/// This allows you to write `entity ~> \.other` instead
+	/// of `entity.relationships.other.id`.
+	public static func ~><Identifier: IdType>(entity: Self, path: KeyPath<Description.Relationships, (Self) -> Identifier>) -> Identifier {
+		return entity.relationships[keyPath: path](entity)
+	}
+
+	/// Access to all Ids of a `ToManyRelationship`.
+	/// This allows you to write `entity ~> \.others` instead
+	/// of `entity.relationships.others.ids`.
+	public static func ~><Identifier: IdType>(entity: Self, path: KeyPath<Description.Relationships, (Self) -> [Identifier]>) -> [Identifier] {
+		return entity.relationships[keyPath: path](entity)
+	}
+}
+
 infix operator ~>
 
 // MARK: - Codable

Sources/JSONAPI/Resource/Poly+PrimaryResource.swift

@@ -0,0 +1,57 @@
+//
+//  Poly+PrimaryResource.swift
+//  JSONAPI
+//
+//  Created by Mathew Polzin on 11/22/18.
+//
+
+import Poly
+
+/// Poly is a protocol to which types that
+/// are polymorphic belong to. Specifically,
+/// Poly1, Poly2, Poly3, etc. types conform
+/// to the Poly protocol. These types allow
+/// typesafe grouping of a number of
+/// disparate types under one roof for
+/// the purposes of JSON API compliant
+/// encoding or decoding.
+public typealias JSONPoly = Poly & PrimaryResource
+
+public typealias PolyWrapped = Codable & Equatable
+
+extension Poly0: PrimaryResource {
+	public init(from decoder: Decoder) throws {
+		throw JSONAPIEncodingError.illegalDecoding("Attempted to decode Poly0, which should represent a thing that is not expected to be found in a document.")
+	}
+
+	public func encode(to encoder: Encoder) throws {
+		throw JSONAPIEncodingError.illegalEncoding("Attempted to encode Poly0, which should represent a thing that is not expected to be found in a document.")
+	}
+}
+
+// MARK: - 1 type
+extension Poly1: PrimaryResource, MaybePrimaryResource where A: PolyWrapped {}
+
+// MARK: - 2 types
+extension Poly2: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped {}
+
+// MARK: - 3 types
+extension Poly3: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped {}
+
+// MARK: - 4 types
+extension Poly4: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped, D: PolyWrapped {}
+
+// MARK: - 5 types
+extension Poly5: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped, D: PolyWrapped, E: PolyWrapped {}
+
+// MARK: - 6 types
+extension Poly6: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped, D: PolyWrapped, E: PolyWrapped, F: PolyWrapped {}
+
+// MARK: - 7 types
+extension Poly7: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped, D: PolyWrapped, E: PolyWrapped, F: PolyWrapped, G: PolyWrapped {}
+
+// MARK: - 8 types
+extension Poly8: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped, D: PolyWrapped, E: PolyWrapped, F: PolyWrapped, G: PolyWrapped, H: PolyWrapped {}
+
+// MARK: - 9 types
+extension Poly9: PrimaryResource, MaybePrimaryResource where A: PolyWrapped, B: PolyWrapped, C: PolyWrapped, D: PolyWrapped, E: PolyWrapped, F: PolyWrapped, G: PolyWrapped, H: PolyWrapped, I: PolyWrapped {}

Sources/JSONAPIArbitrary/APIDescription+Arbitrary.swift

@@ -0,0 +1,24 @@
+//
+//  APIDescription+Arbitrary.swift
+//  JSONAPIArbitrary
+//
+//  Created by Mathew Polzin on 1/21/19.
+//
+
+import SwiftCheck
+import JSONAPI
+
+extension APIDescription: Arbitrary where Meta: Arbitrary {
+	public static var arbitrary: Gen<APIDescription<Meta>> {
+		return Gen.compose { c in
+			APIDescription(version: c.generate(),
+						   meta: c.generate())
+		}
+	}
+}
+
+extension NoAPIDescription: Arbitrary {
+	public static var arbitrary: Gen<NoAPIDescription> {
+		return Gen.pure(.none)
+	}
+}

Sources/JSONAPIArbitrary/Attribute+Arbitrary.swift

@@ -0,0 +1,20 @@
+//
+//  Attribute+Arbitrary.swift
+//  JSONAPIArbitrary
+//
+//  Created by Mathew Polzin on 1/15/19.
+//
+
+import SwiftCheck
+import JSONAPI
+
+extension Attribute: Arbitrary where RawValue: Arbitrary {
+	public static var arbitrary: Gen<Attribute<RawValue>> {
+		return RawValue.arbitrary.map { .init(value: $0) }
+	}
+}
+
+// Cannot conform TransformedAttribute to Arbitrary here
+// because there is no way to guarantee that an arbitrary
+// RawValue will successfully transform or that an
+// arbitrary Value will successfully reverse-transform.

Sources/JSONAPIArbitrary/Document+Arbitrary.swift

@@ -0,0 +1,110 @@
+//
+//  Document+Arbitrary.swift
+//  JSONAPIArbitrary
+//
+//  Created by Mathew Polzin on 1/21/19.
+//
+
+import SwiftCheck
+import JSONAPI
+
+extension Document.Body.Data: Arbitrary where PrimaryResourceBody: Arbitrary, IncludeType: Arbitrary, MetaType: Arbitrary, LinksType: Arbitrary {
+	public static var arbitrary: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>.Body.Data> {
+		return Gen.compose { c in
+			Document.Body.Data(primary: c.generate(),
+							   includes: c.generate(),
+							   meta: c.generate(),
+							   links: c.generate())
+		}
+	}
+}
+
+extension Document.Body: Arbitrary where PrimaryResourceBody: Arbitrary, IncludeType: Arbitrary, MetaType: Arbitrary, LinksType: Arbitrary, Error: Arbitrary {
+	public static var arbitrary: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>.Body> {
+		return Gen.one(of: [
+			arbitraryData,
+			arbitraryErrors
+		])
+	}
+}
+
+extension Document.Body where PrimaryResourceBody: Arbitrary, IncludeType: Arbitrary, MetaType: Arbitrary, LinksType: Arbitrary {
+	/// Arbitrary Document.Body with data (guaranteed to not
+	/// be an error body).
+	public static var arbitraryData: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>.Body> {
+		return Document.Body.Data.arbitrary.map(Document.Body.data)
+	}
+}
+
+extension Document.Body where MetaType: Arbitrary, LinksType: Arbitrary, Error: Arbitrary {
+	/// Arbitrary Document.Body with errors (guaranteed to not
+	/// be a data body).
+	public static var arbitraryErrors: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>.Body> {
+		return Gen.compose { c in
+			Document.Body.errors(c.generate(),
+								 meta: c.generate(),
+								 links: c.generate())
+		}
+	}
+}
+
+extension Document.Body where Error: Arbitrary {
+	/// Arbitrary Document.Body with errors but no
+	/// metadata or links (also guaranteed to not
+	/// be a data body).
+	public static var arbitraryErrorsWithoutMetaOrLinks: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>.Body> {
+		return Gen.compose { c in
+			Document.Body.errors(c.generate(),
+								 meta: nil,
+								 links: nil)
+		}
+	}
+}
+
+extension Document: Arbitrary where PrimaryResourceBody: Arbitrary, IncludeType: Arbitrary, MetaType: Arbitrary, LinksType: Arbitrary, Error: Arbitrary, APIDescription: Arbitrary {
+	public static var arbitrary: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>> {
+		return Gen.one(of: [
+			arbitraryData,
+			arbitraryErrors
+		])
+	}
+}
+
+extension Document where PrimaryResourceBody: Arbitrary, IncludeType: Arbitrary, MetaType: Arbitrary, LinksType: Arbitrary, APIDescription: Arbitrary {
+	/// Arbitrary Document with data (guaranteed to not
+	/// be an error body).
+	public static var arbitraryData: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>> {
+		return Gen.compose { c in
+			Document(apiDescription: c.generate(),
+					 body: c.generate(),
+					 includes: c.generate(),
+					 meta: c.generate(),
+					 links: c.generate())
+		}
+	}
+}
+
+extension Document where MetaType: Arbitrary, LinksType: Arbitrary, Error: Arbitrary, APIDescription: Arbitrary {
+	/// Arbitrary Document with errors (guaranteed to not
+	/// be a data body).
+	public static var arbitraryErrors: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>> {
+		return Gen.compose { c in
+			Document(apiDescription: c.generate(),
+					 errors: c.generate(),
+					 meta: c.generate(),
+					 links: c.generate())
+		}
+	}
+}
+
+extension Document where Error: Arbitrary, APIDescription: Arbitrary {
+	/// Arbitrary Document with errors but no
+	/// metadata or links (also guaranteed to not
+	/// be a data body).
+	public static var arbitraryErrors: Gen<Document<PrimaryResourceBody, MetaType, LinksType, IncludeType, APIDescription, Error>> {
+		return Gen.compose { c in
+			Document(apiDescription: c.generate(),
+					 errors: c.generate())
+		}
+	}
+}