go/types: add a test for argument error unwrapping

Add a sanity-check test that ArgumentErrors unwrap their inner Err.

Change-Id: I5a670a490deeabc03a64e42b3843f79d622ba958
Reviewed-on: https://go-review.googlesource.com/c/go/+/351338
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index d59d3d8923af2c40e04cac6ab3e6b4c77a56700c..f1a820988fa481526a94fb217057d7a3d1011f15 100644 (file)
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -2012,6 +2012,20 @@ func TestInstantiateErrors(t *testing.T) {
        }
 }
 
+func TestArgumentErrorUnwrapping(t *testing.T) {
+       var err error = &ArgumentError{
+               Index: 1,
+               Err:   Error{Msg: "test"},
+       }
+       var e Error
+       if !errors.As(err, &e) {
+               t.Fatalf("error %v does not wrap types.Error", err)
+       }
+       if e.Msg != "test" {
+               t.Errorf("e.Msg = %q, want %q", e.Msg, "test")
+       }
+}
+
 func TestInstanceIdentity(t *testing.T) {
        imports := make(testImporter)
        conf := Config{Importer: imports}