Add test cases

src/sed/compiler.rs

@@ -2725,6 +2725,19 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_compile_text_command_posix_incomplete() {
+        let (mut lines, mut chars) = make_providers("i\\");
+        let mut cmd = Command::default();
+        let mut context = ProcessingContext {
+            posix: true,
+            ..Default::default()
+        };
+        let result = compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context);
+        let err = result.unwrap_err().to_string();
+        assert!(err.contains("incomplete command"));
+    }
+
     #[test]
     fn test_compile_text_command_gnu_optional_backslash() {
         let mut chars = make_char_provider("athere");

tests/by-util/test_sed.rs

@@ -1066,6 +1066,15 @@ fn test_undefined_label() {
         .stderr_is("sed: <script argument 1>:1:1: error: undefined label `foo'\n");
 }
 
+#[test]
+fn test_incomplete_test_command_posix() {
+    new_ucmd!()
+        .args(&["--posix", "i\\"])
+        .fails()
+        .code_is(1)
+        .stderr_is("sed: :0:3: error: incomplete command\n");
+}
+
 #[test]
 fn test_addr0_non_posix() {
     new_ucmd!()