feat: Allow testing JSON schema error message

jsonschema/testing.go

@@ -9,9 +9,10 @@ import (
 )
 
 type TestCase struct {
-	Name string
-	Spec string
-	Err  bool
+	Name         string
+	Spec         string
+	Err          bool
+	ErrorMessage string
 }
 
 func TestJSONSchema(t *testing.T, schema string, cases []TestCase) {
@@ -25,8 +26,9 @@ func TestJSONSchema(t *testing.T, schema string, cases []TestCase) {
 			var v any
 			require.NoErrorf(t, json.Unmarshal([]byte(tc.Spec), &v), "failed input:\n%s\n", tc.Spec)
 			err := validator.Validate(v)
-			if tc.Err {
+			if tc.Err || tc.ErrorMessage != "" {
 				require.Errorf(t, err, "failed input:\n%s\n", tc.Spec)
+				require.ErrorContains(t, err, tc.ErrorMessage)
 			} else {
 				require.NoErrorf(t, err, "failed input:\n%s\n", tc.Spec)
 			}

jsonschema/testing_test.go

@@ -0,0 +1,41 @@
+package jsonschema
+
+import (
+	"testing"
+)
+
+type schemaTestCase struct {
+	name   string
+	schema string
+	cases  []TestCase
+}
+
+func TestJSONSchemaCases(t *testing.T) {
+	tests := []schemaTestCase{
+		{
+			name:   "simple",
+			schema: `{ "type": "object", "properties": { "name": { "type": "string" } } }`,
+			cases: []TestCase{
+				{
+					Name: "valid",
+					Spec: `{ "name": "test" }`,
+				},
+				{
+					Name: "invalid",
+					Spec: `{ "name": 1 }`,
+					Err:  true,
+				},
+				{
+					Name:         "invalid with error message",
+					Spec:         `{ "name": 1 }`,
+					ErrorMessage: "expected string, but got number",
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			TestJSONSchema(t, tt.schema, tt.cases)
+		})
+	}
+}