go/types/objectpath,internal/aliases: miscellaneous clean up of tests that set gotypesalias

* Fix default value test ("") for TestNewAlias.
* Updates references to 1.19 to 1.22.

Change-Id: I9c19621e820c90c265235afff863863d03f2d171
Reviewed-on: https://go-review.googlesource.com/c/tools/+/615696
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

go/types/objectpath/objectpath_test.go

@@ -34,7 +34,7 @@ func TestPaths(t *testing.T) {
 }
 
 func testPaths(t *testing.T, gotypesalias int) {
-	// override default set by go1.19 in go.mod
+	// override default set by go1.22 in go.mod
 	t.Setenv("GODEBUG", fmt.Sprintf("gotypesalias=%d", gotypesalias))
 
 	const src = `

internal/aliases/aliases_test.go

@@ -45,8 +45,8 @@ func TestNewAlias(t *testing.T) {
 
 	for _, godebug := range []string{
 		// The default gotypesalias value follows the x/tools/go.mod version
-		// The go.mod is at 1.19 so the default is gotypesalias=0.
-		// "", // Use the default GODEBUG value.
+		// The go.mod is at 1.22 so the default is gotypesalias=0.
+		"", // Use the default GODEBUG value (off).
 		"gotypesalias=0",
 		"gotypesalias=1",
 	} {
@@ -67,10 +67,14 @@ func TestNewAlias(t *testing.T) {
 				t.Errorf("Expected Unalias(A)==%q. got %q", want, got)
 			}
 
-			if godebug != "gotypesalias=0" {
-				if _, ok := A.Type().(*types.Alias); !ok {
-					t.Errorf("Expected A.Type() to be a types.Alias(). got %q", A.Type())
+			wantAlias := godebug == "gotypesalias=1"
+			_, gotAlias := A.Type().(*types.Alias)
+			if gotAlias != wantAlias {
+				verb := "to be"
+				if !wantAlias {
+					verb = "to not be"
 				}
+				t.Errorf("Expected A.Type() %s a types.Alias(). got %q", verb, A.Type())
 			}
 		})
 	}
@@ -83,9 +87,12 @@ func TestNewAlias(t *testing.T) {
 //
 // Requires gotypesalias GODEBUG and aliastypeparams GOEXPERIMENT.
 func TestNewParameterizedAlias(t *testing.T) {
+	testenv.NeedsGo1Point(t, 23)
+	if testenv.Go1Point() == 23 {
 		testenv.NeedsGoExperiment(t, "aliastypeparams")
+	}
 
-	t.Setenv("GODEBUG", "gotypesalias=1") // needed until gotypesalias is removed (1.27).
+	t.Setenv("GODEBUG", "gotypesalias=1") // needed until gotypesalias is removed (1.27) or enabled by go.mod (1.23).
 	enabled := aliases.Enabled()
 	if !enabled {
 		t.Fatal("Need materialized aliases enabled")