go/packages/packagestest: do not walk packages and their test variants

Currently, where a package has a test variant, we end up walking the
non-_test.go files twice: once when walking the package itself, the
second time when walking the test variant. In the gopls tests, this
means we end up double-counting the number of symbols (via the @symbol
annotation) in a package.

Extend the existing expect_test.go to demonstrate the problem is fixed
(a test which fails when the fix is not in place)

Change-Id: Ifd68b3d86e24f19d3f8efc3af71494b7d28b0acb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/228761
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

go/packages/packagestest/expect.go

@@ -16,6 +16,7 @@ import (
 
 	"golang.org/x/tools/go/expect"
 	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/internal/packagesinternal"
 	"golang.org/x/tools/internal/span"
 )
 
@@ -151,7 +152,18 @@ func (e *Exported) getNotes() error {
 	if err != nil {
 		return fmt.Errorf("unable to load packages for directories %s: %v", dirs, err)
 	}
+	// We need to avoid walking packages and their test variants, otherwise we
+	// double-count
+	pkgsWithTestVariants := make(map[string]bool)
 	for _, pkg := range pkgs {
+		if forTest := packagesinternal.GetForTest(pkg); forTest != "" {
+			pkgsWithTestVariants[forTest] = true
+		}
+	}
+	for _, pkg := range pkgs {
+		if pkgsWithTestVariants[pkg.ID] {
+			continue
+		}
 		for _, filename := range pkg.GoFiles {
 			content, err := e.FileContents(filename)
 			if err != nil {

go/packages/packagestest/expect_test.go

@@ -19,10 +19,10 @@ func TestExpect(t *testing.T) {
 		Files: packagestest.MustCopyFileTree("testdata"),
 	}})
 	defer exported.Cleanup()
-	count := 0
+	checkCount := 0
 	if err := exported.Expect(map[string]interface{}{
 		"check": func(src, target token.Position) {
-			count++
+			checkCount++
 		},
 		"boolArg": func(n *expect.Note, yes, no bool) {
 			if !yes {
@@ -61,7 +61,12 @@ func TestExpect(t *testing.T) {
 	}); err != nil {
 		t.Fatal(err)
 	}
-	if count == 0 {
-		t.Fatalf("No tests were run")
+	// We expect to have walked the @check annotations in all .go files,
+	// including _test.go files (XTest or otherwise). But to have walked the
+	// non-_test.go files only once. Hence wantCheck = 3 (testdata/test.go) + 1
+	// (testdata/test_test.go) + 1 (testdata/x_test.go)
+	wantCheck := 5
+	if wantCheck != checkCount {
+		t.Fatalf("Expected @check count of %v; got %v", wantCheck, checkCount)
 	}
 }

go/packages/packagestest/testdata/test_test.go

@@ -0,0 +1,3 @@
+package fake1
+
+type ATestType string //@check("ATestType","ATestType")

go/packages/packagestest/testdata/x_test.go

@@ -0,0 +1,3 @@
+package fake1_test
+
+type AnXTestType string //@check("AnXTestType","AnXTestType")

internal/lsp/testdata/lsp/summary.txt.golden

@@ -1,8 +1,8 @@
 -- summary --
 CodeLensCount = 2
-CompletionsCount = 238
-CompletionSnippetCount = 75
-UnimportedCompletionsCount = 11
+CompletionsCount = 237
+CompletionSnippetCount = 74
+UnimportedCompletionsCount = 6
 DeepCompletionsCount = 5
 FuzzyCompletionsCount = 8
 RankedCompletionsCount = 120