internal/lsp/cache: intermediate test variants aren't workspace packages

When you write a test in (say) the fmt package, you get a test variant
augmented with the test files. In many cases you also get test variants
of the things the fmt package depends on. The primary test variant,
(fmt [fmt.test]) is interesting to us, because it contains the tests.
But the intermediate variants (testing [fmt.test]) aren't -- the user
can only get to them indirectly. We certainly don't need to fully parse
them.

Treat intermediate test variants as non-workspace packages. This doesn't
accomplish much yet but paves the way for later optimizations.

Updates golang/go#36943.

Change-Id: I1a20abcd2d67767f07132a75a20f098be6f19a76
Reviewed-on: https://go-review.googlesource.com/c/tools/+/236397
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/cache/load.go

@@ -212,16 +212,21 @@ func (s *snapshot) setMetadata(ctx context.Context, pkgPath packagePath, pkg *pa
 	// Set the workspace packages. If any of the package's files belong to the
 	// view, then the package is considered to be a workspace package.
 	for _, uri := range append(m.compiledGoFiles, m.goFiles...) {
-		// If the package's files are in this view, mark it as a workspace package.
-		if s.view.contains(uri) {
-			// A test variant of a package can only be loaded directly by loading
-			// the non-test variant with -test. Track the import path of the non-test variant.
-			if m.forTest != "" {
-				s.workspacePackages[m.id] = m.forTest
-			} else {
-				s.workspacePackages[m.id] = pkgPath
-			}
-			break
+		if !s.view.contains(uri) {
+			continue
+		}
+
+		// The package's files are in this view. It may be a workspace package.
+		switch m.forTest {
+		case "":
+			// A normal package.
+			s.workspacePackages[m.id] = pkgPath
+		case m.pkgPath:
+			// The test variant of some workspace package. To load it, we need to
+			// load the non-test variant with -test.
+			s.workspacePackages[m.id] = m.forTest
+		default:
+			// A test variant of some intermediate package. We don't care about it.
 		}
 	}
 	return m, nil