go/packages: add a Module field to the Package struct

This change introduces Module and ModuleError struct types to the
packages package with the same types as defined in the cmd/go
documentation for module information output by go list (with the
exception of the Module type's Versions and Update fields).
go/packages will fill the module struct with the module information
output by go list. Drivers that support modules can also provide
module information by filling the Module fields in the packages in
their driverResponses.

Fixes golang/go#35921

Change-Id: Icbdf79869f09d26f6a01c3670146ace4f6ffa25e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/234219
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/go/packages/packages_test.go b/go/packages/packages_test.go
index 9d2914344..8c8519638 100644
--- a/go/packages/packages_test.go
+++ b/go/packages/packages_test.go
@@ -2636,6 +2636,46 @@ func testIssue37529(t *testing.T, exporter packagestest.Exporter) {
 	}
 }
 
+func TestModule(t *testing.T) {
+	packagestest.TestAll(t, testModule)
+}
+func testModule(t *testing.T, exporter packagestest.Exporter) {
+	exported := packagestest.Export(t, exporter, []packagestest.Module{{
+		Name:  "golang.org/fake",
+		Files: map[string]interface{}{"a/a.go": `package a`}}})
+	exported.Config.Mode = packages.NeedModule
+	rootDir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "a/a.go")))
+
+	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(initial) != 1 {
+		t.Fatal("want exactly one package, got ", initial)
+	}
+	a := initial[0]
+	switch exported.Exporter.Name() {
+	case "GOPATH":
+		if a.Module != nil {
+			t.Fatal("package.Module: want nil, got ", a.Module)
+		}
+	case "Modules":
+		// Make sure Modules field is set, and spot check a few of its fields.
+		if a.Module == nil {
+			t.Fatal("package.Module: want non-nil, got nil")
+		}
+		if a.Module.Path != "golang.org/fake" {
+			t.Fatalf("package.Modile.Path: want \"golang.org/fake\", got %q", a.Module.Path)
+		}
+		if a.Module.GoMod != filepath.Join(rootDir, "go.mod") {
+			t.Fatalf("package.Module.GoMod: want %q, got %q", filepath.Join(rootDir, "go.mod"), a.Module.GoMod)
+		}
+	default:
+		t.Fatalf("Expected exporter to be GOPATH or Modules, got %v", exported.Exporter.Name())
+	}
+}
+
 func errorMessages(errors []packages.Error) []string {
 	var msgs []string
 	for _, err := range errors {