net: retighten test harnesses for dial cancelation

Updates #11225.

Change-Id: I6c33d577f144643781f370ba2ab0997d1c1a3820
Reviewed-on: https://go-review.googlesource.com/17880Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/dial_test.go

@@ -722,7 +722,7 @@ func TestDialCancel(t *testing.T) {
 	if runtime.GOOS == "plan9" || runtime.GOOS == "nacl" {
 		// plan9 is not implemented and nacl doesn't have
 		// external network access.
-		t.Skip("skipping on %s", runtime.GOOS)
+		t.Skipf("skipping on %s", runtime.GOOS)
 	}
 	onGoBuildFarm := testenv.Builder() != ""
 	if testing.Short() && !onGoBuildFarm {
@@ -767,6 +767,9 @@ func TestDialCancel(t *testing.T) {
 			c.Close()
 			t.Fatal("unexpected successful connection")
 		case err := <-errc:
+			if perr := parseDialError(err); perr != nil {
+				t.Error(perr)
+			}
 			if ticks < cancelTick {
 				t.Fatalf("dial error after %d ticks (%d before cancel sent): %v",
 					ticks, cancelTick-ticks, err)

src/net/error_test.go

@@ -93,7 +93,7 @@ second:
 		goto third
 	}
 	switch nestedErr {
-	case errClosing, errMissingAddress:
+	case errCanceled, errClosing, errMissingAddress:
 		return nil
 	}
 	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)
@@ -413,7 +413,7 @@ second:
 		goto third
 	}
 	switch nestedErr {
-	case errClosing, errTimeout, ErrWriteToConnected, io.ErrUnexpectedEOF:
+	case errCanceled, errClosing, errTimeout, ErrWriteToConnected, io.ErrUnexpectedEOF:
 		return nil
 	}
 	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)