testing: add a stub for t.Parallel()

src/testing/testing.go

@@ -64,6 +64,7 @@ type TB interface {
 	Skipf(format string, args ...interface{})
 	Skipped() bool
 	Helper()
+	Parallel()
 }
 
 var _ TB = (*T)(nil)
@@ -194,6 +195,11 @@ func (c *common) Helper() {
 	// Unimplemented.
 }
 
+// Parallel is not implemented, it is only provided for compatibility.
+func (c *common) Parallel() {
+	// Unimplemented.
+}
+
 // Run runs a subtest of f t called name. It waits until the subtest is finished
 // and returns whether the subtest succeeded.
 func (t *T) Run(name string, f func(t *T)) bool {