From d688a81d8e7c1cc9fbb54a9fd9c9142c04cf5620 Mon Sep 17 00:00:00 2001
From: Nicholas Katsaros <nick@nickkatsaros.com>
Date: Sat, 15 Jul 2017 16:41:41 -0600
Subject: [PATCH] GOPATH detection now works when GOPATH is a symlink

---
 context.go            |  5 +++++
 context_test.go       | 20 +++++++++++++++++---
 internal/test/test.go | 26 ++++++++++++++++----------
 3 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/context.go b/context.go
index cec883133b..252c53ed51 100644
--- a/context.go
+++ b/context.go
@@ -212,6 +212,11 @@ func (c *Ctx) DetectProjectGOPATH(p *Project) (string, error) {
 // detectGOPATH detects the GOPATH for a given path from ctx.GOPATHs.
 func (c *Ctx) detectGOPATH(path string) (string, error) {
 	for _, gp := range c.GOPATHs {
+		// Evaluate symlinks in case the user's GOPATH contains a symlink.
+		gp, err := filepath.EvalSymlinks(gp)
+		if err != nil {
+			return "", errors.New("failed to evaluate symlinks on GOPATH")
+		}
 		if fs.HasFilepathPrefix(path, gp) {
 			return gp, nil
 		}
diff --git a/context_test.go b/context_test.go
index 4ce9c0521d..bee0604b20 100644
--- a/context_test.go
+++ b/context_test.go
@@ -362,9 +362,11 @@ func TestDetectProjectGOPATH(t *testing.T) {
 
 	h.TempDir("go")
 	h.TempDir("go-two")
+	h.TempDir("go-symgopath")
+	h.TempSymlink("go-symgopath", "go-three")
 
 	ctx := &Ctx{
-		GOPATHs: []string{h.Path("go"), h.Path("go-two")},
+		GOPATHs: []string{h.Path("go"), h.Path("go-two"), h.Path("go-three")},
 	}
 
 	h.TempDir("go/src/real/path")
@@ -376,12 +378,14 @@ func TestDetectProjectGOPATH(t *testing.T) {
 	h.TempDir(filepath.Join("go", "src", "sym", "path"))
 	h.TempDir(filepath.Join("go", "src", " real", "path"))
 	h.TempDir(filepath.Join("go-two", "src", "real", "path"))
+	h.TempDir(filepath.Join("go-symgopath", "src", "real", "path"))
 
 	testcases := []struct {
 		name         string
 		root         string
 		resolvedRoot string
 		GOPATH       string
+		realGOPATH   string
 		expectErr    bool
 	}{
 		{
@@ -432,6 +436,13 @@ func TestDetectProjectGOPATH(t *testing.T) {
 			resolvedRoot: filepath.Join(ctx.GOPATHs[0], "src", " real", "path"),
 			GOPATH:       ctx.GOPATHs[0],
 		},
+		{
+			name:         "GOPATH-is-a-symlink",
+			root:         filepath.Join(h.Path("go-symgopath"), "src", "real", "path"),
+			resolvedRoot: filepath.Join(h.Path("go-symgopath"), "src", "real", "path"),
+			GOPATH:       ctx.GOPATHs[2],
+			realGOPATH:   h.Path("go-symgopath"),
+		},
 	}
 
 	for _, tc := range testcases {
@@ -447,8 +458,11 @@ func TestDetectProjectGOPATH(t *testing.T) {
 			} else if tc.expectErr && err == nil {
 				t.Fatalf("expected an error, got nil and gopath %s", GOPATH)
 			}
-			if GOPATH != tc.GOPATH {
-				t.Errorf("expected GOPATH %s, got %s", tc.GOPATH, GOPATH)
+			if tc.realGOPATH == "" {
+				tc.realGOPATH = tc.GOPATH
+			}
+			if GOPATH != tc.realGOPATH {
+				t.Errorf("expected GOPATH %s, got %s", tc.realGOPATH, GOPATH)
 			}
 		})
 	}
diff --git a/internal/test/test.go b/internal/test/test.go
index c2c0faa40a..80ff1df331 100644
--- a/internal/test/test.go
+++ b/internal/test/test.go
@@ -497,6 +497,16 @@ func (h *Helper) TempDir(path string) {
 	}
 }
 
+// TempSymlink adds a temporary symlink for a run of testgo.
+func (h *Helper) TempSymlink(old, new string) {
+	h.makeTempdir()
+	fullOldPath := filepath.Join(h.tempdir, old)
+	fullNewPath := filepath.Join(h.tempdir, new)
+	if err := os.Symlink(fullOldPath, fullNewPath); err != nil {
+		h.t.Fatalf("%+v", errors.Errorf("Unable to create symlink from %s -> %s", fullOldPath, fullNewPath))
+	}
+}
+
 // Path returns the absolute pathname to file with the temporary
 // directory.
 func (h *Helper) Path(name string) string {
@@ -504,19 +514,15 @@ func (h *Helper) Path(name string) string {
 		h.t.Fatalf("%+v", errors.Errorf("internal testsuite error: path(%q) with no tempdir", name))
 	}
 
-	var joined string
-	if name == "." {
-		joined = h.tempdir
-	} else {
-		joined = filepath.Join(h.tempdir, name)
+	evaled, err := filepath.EvalSymlinks(h.tempdir)
+	if err != nil {
+		h.t.Fatalf("%+v", errors.Wrapf(err, "internal testsuite error: could not evaluate symlinks for dir(%q)", h.tempdir))
 	}
 
-	// Ensure it's the absolute, symlink-less path we're returning
-	abs, err := filepath.EvalSymlinks(joined)
-	if err != nil {
-		h.t.Fatalf("%+v", errors.Wrapf(err, "internal testsuite error: could not get absolute path for dir(%q)", joined))
+	if name == "." {
+		return evaled
 	}
-	return abs
+	return filepath.Join(evaled, name)
 }
 
 // MustExist fails if path does not exist.