encoding/jsonschema: add test for date-time format

The "date-time" format is supposed to be recognized but is not.
This errant behavior will be fixed in a subequent CL.

This error is only recognized in strict-keyword mode,
which is always enabled when jsonschema is invoked
via OpenAPI, so also make sure that that mode is
enabled when openAPI mode is enabled in the jsonschema
tests, avoiding the need to add an extra `#strictKeywords`
tag to openapi tests in encoding/jsonschema.

For #3454.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I429c4c013481837d4f72d94367329ce010c55604
Dispatch-Trailer: {"type":"trybot","CL":1201351,"patchset":3,"ref":"refs/changes/51/1201351/3","targetBranch":"master"}

encoding/jsonschema/decode_test.go

@@ -79,6 +79,7 @@ func TestDecode(t *testing.T) {
 				// OpenAPI doesn't have a JSON Schema URI so it gets a special case.
 				cfg.DefaultVersion = jsonschema.VersionOpenAPI
 				cfg.Root = "#/components/schemas/"
+				cfg.StrictKeywords = true // OpenAPI always uses strict keywords
 				cfg.Map = func(p token.Pos, a []string) ([]ast.Label, error) {
 					// Just for testing: does not validate the path.
 					return []ast.Label{ast.NewIdent("#" + a[len(a)-1])}, nil
@@ -90,7 +91,7 @@ func TestDecode(t *testing.T) {
 			}
 		}
 		cfg.Strict = t.HasTag("strict")
-		cfg.StrictKeywords = t.HasTag("strictKeywords")
+		cfg.StrictKeywords = cfg.StrictKeywords || t.HasTag("strictKeywords")
 		cfg.StrictFeatures = t.HasTag("strictFeatures")
 
 		ctx := t.CueContext()

encoding/jsonschema/testdata/txtar/openapi_date-time.txtar

@@ -0,0 +1,13 @@
+#version: openapi
+
+-- schema.yaml --
+components:
+  schemas:
+    DateTime:
+        type: string
+        format: date-time
+
+-- out/decode/extract --
+ERROR:
+unknown format "date-time":
+    schema.yaml:5:9