diff --git a/playground/impl_test.go b/playground/impl_test.go
index 6d1fca6c6d..ad7c9e18ae 100644
--- a/playground/impl_test.go
+++ b/playground/impl_test.go
@@ -30,26 +30,76 @@ var testTable = []struct {
 	{inputCUE, functionExport, outputCUE, "", "\n", ""},
 	{inputCUE, functionExport, outputCUE, "a: b: 5\na: c: 4", "a: {\n\tb: 5\n\tc: 4\n}\n", ""},
 	{inputCUE, functionExport, outputJSON, "test: 5", "{\n    \"test\": 5\n}\n", ""},
+
+	// Incomplete values.
+	{inputCUE, functionExport, outputCUE, "foo: int", "foo: int\n", ""},
+	{inputCUE, functionExport, outputJSON, "foo: int", "", "foo: incomplete value int"},
+
+	// Selecting defaults.
+	{inputCUE, functionExport, outputCUE, "foo: int | *3", "foo: 3\n", ""},
+	{inputCUE, functionExport, outputJSON, "foo: int | *3", "{\n    \"foo\": 3\n}\n", ""},
+
+	// Pattern constraints with different output formats; see https://cuelang.org/issue/2417
+	{
+		inputCUE, functionExport, outputCUE,
+		`
+			[ID=_]: x: y: ID
+			"foo": {}
+		`,
+		"foo: {\n\tx: {\n\t\ty: \"foo\"\n\t}\n}\n",
+		"",
+	},
+	{
+		inputCUE, functionExport, outputJSON,
+		`
+			[ID=_]: x: y: ID
+			"foo": {}
+		`,
+		"",
+		"failed to encode: foo.x.y: incomplete value string",
+	},
+
+	// Cases which one could argue should be errors, beyond just being incomplete.
+	{
+		inputCUE, functionExport, outputCUE,
+		`
+			x: string
+			y: (x): string
+		`,
+		"x: string\ny: {\n\t(x): string\n}\n",
+		"",
+	},
+	{
+		inputCUE, functionExport, outputCUE,
+		`
+			x: x2: "foo"
+			y: x.missing
+		`,
+		"x: {\n\tx2: \"foo\"\n}\ny: x.missing\n",
+		"",
+	},
 }
 
 func TestHandleCUECompile(t *testing.T) {
 	for _, tv := range testTable {
-		desc := fmt.Sprintf("handleCUECompile(%q, %q, %q, %q)", tv.In, tv.Fn, tv.Out, tv.InVal)
-		out, err := handleCUECompile(tv.In, tv.Fn, tv.Out, tv.InVal)
-		if tv.Err != "" {
-			if err != nil {
-				if err.Error() != tv.Err {
-					t.Fatalf("%v: expected error string %q; got %q", desc, tv.Err, err)
+		t.Run("", func(t *testing.T) {
+			desc := fmt.Sprintf("handleCUECompile(%q, %q, %q, %q)", tv.In, tv.Fn, tv.Out, tv.InVal)
+			out, err := handleCUECompile(tv.In, tv.Fn, tv.Out, tv.InVal)
+			if tv.Err != "" {
+				if err != nil {
+					if err.Error() != tv.Err {
+						t.Fatalf("%v: expected error string %q; got %q", desc, tv.Err, err)
+					}
+				} else {
+					t.Fatalf("%v: expected error, did not see one. Output was %q", desc, out)
 				}
 			} else {
-				t.Fatalf("%v: expected error, did not see one. Output was %q", desc, out)
-			}
-		} else {
-			if err != nil {
-				t.Fatalf("%v: got unexpected error: %v", desc, err)
-			} else if out != tv.OutVal {
-				t.Fatalf("%v: expected output %q: got %q", desc, tv.OutVal, out)
+				if err != nil {
+					t.Fatalf("%v: got unexpected error: %v", desc, err)
+				} else if out != tv.OutVal {
+					t.Fatalf("%v: expected output %q: got %q", desc, tv.OutVal, out)
+				}
 			}
-		}
+		})
 	}
 }