rename func, improve comments

- `project.go`
  - Rename method {checkCfgFilenames => checkGopkgFilenames}
  - Improve funciton comment as suggested by @sdboyer
  - Fix ambigious comment explaining rationale behind early return.
- Add comment explaining why we do not use `fs.IsCaseSensitiveFilesystem` for
  skipping following tests:
  - context_test.go#TestLoadProjectGopkgFilenames
  - project_test.go#TestCheckGopkgFilenames
  - fs_test.go#TestReadActualFilenames

context.go

@@ -105,7 +105,7 @@ func (c *Ctx) LoadProject() (*Project, error) {
 		return nil, err
 	}
 
-	err = checkCfgFilenames(root)
+	err = checkGopkgFilenames(root)
 	if err != nil {
 		return nil, err
 	}

context_test.go

@@ -264,14 +264,20 @@ func TestLoadProjectNoSrcDir(t *testing.T) {
 	}
 }
 
-func TestLoadProjectCfgFileCase(t *testing.T) {
+func TestLoadProjectGopkgFilenames(t *testing.T) {
+	// We are trying to skip this test on file systems which are case-sensiive. We could
+	// have used `fs.IsCaseSensitiveFilesystem` for this check. However, the code we are
+	// testing also relies on `fs.IsCaseSensitiveFilesystem`. So a bug in
+	// `fs.IsCaseSensitiveFilesystem` could prevent this test from being run. This is the
+	// only scenario where we prefer the OS heuristic over doing the actual work of
+	// validating filesystem case sensitivity via `fs.IsCaseSensitiveFilesystem`.
 	if runtime.GOOS != "windows" && runtime.GOOS != "darwin" {
 		t.Skip("skip this test on non-Windows, non-macOS")
 	}
 
 	// Here we test that a manifest filename with incorrect case throws an error. Similar
 	// error will also be thrown for the lock file as well which has been tested in
-	// `project_test.go#TestCheckCfgFilenames`. So not repeating here.
+	// `project_test.go#TestCheckGopkgFilenames`. So not repeating here.
 
 	h := test.NewHelper(t)
 	defer h.Cleanup()

internal/fs/fs.go

@@ -272,7 +272,7 @@ var errPathNotDir = errors.New("given path is not a directory")
 // `os.Stat` and return a map with key and value as filenames which exist in the folder.
 //
 // Otherwise, it reads the contents of the directory and returns a map which has the
-// given file name as the key and actual filename as the value if it was found.
+// given file name as the key and actual filename as the value(if it was found).
 func ReadActualFilenames(dirPath string, names []string) (map[string]string, error) {
 	actualFilenames := make(map[string]string, len(names))
 	if len(names) == 0 {

internal/fs/fs_test.go

@@ -265,6 +265,12 @@ func TestIsCaseSensitiveFilesystem(t *testing.T) {
 }
 
 func TestReadActualFilenames(t *testing.T) {
+	// We are trying to skip this test on file systems which are case-sensiive. We could
+	// have used `fs.IsCaseSensitiveFilesystem` for this check. However, the code we are
+	// testing also relies on `fs.IsCaseSensitiveFilesystem`. So a bug in
+	// `fs.IsCaseSensitiveFilesystem` could prevent this test from being run. This is the
+	// only scenario where we prefer the OS heuristic over doing the actual work of
+	// validating filesystem case sensitivity via `fs.IsCaseSensitiveFilesystem`.
 	if runtime.GOOS != "windows" && runtime.GOOS != "darwin" {
 		t.Skip("skip this test on non-Windows, non-macOS")
 	}
@@ -332,7 +338,8 @@ func TestReadActualFilenames(t *testing.T) {
 			t.Fatalf("unexpected error: %+v", err)
 		}
 		if !reflect.DeepEqual(c.want, got) {
-			t.Fatalf("returned value does not match expected: \n\t(GOT) %v\n\t(WNT) %v", got, c.want)
+			t.Fatalf("returned value does not match expected: \n\t(GOT) %v\n\t(WNT) %v",
+				got, c.want)
 		}
 	}
 }

project.go

@@ -42,17 +42,19 @@ func findProjectRoot(from string) (string, error) {
 	}
 }
 
-// checkCfgFilenames validates filename case for the manifest and lock files.
+// checkGopkgFilenames validates filename case for the manifest and lock files.
 //
-// This is relevant on case-insensitive file systems like Windows and macOS.
+// This is relevant on case-insensitive file systems like the defaults in Windows and
+// macOS.
 //
 // If manifest file is not found, it returns an error indicating the project could not be
 // found. If it is found but the case does not match, an error is returned. If a lock
 // file is not found, no error is returned as lock file is optional. If it is found but
 // the case does not match, an error is returned.
-func checkCfgFilenames(projectRoot string) error {
-	// ReadActualFilenames is actually costly. Since this check is not relevant to
-	// case-sensitive filesystems like ext4(linux), try for an early return.
+func checkGopkgFilenames(projectRoot string) error {
+	// ReadActualFilenames is actually costly. Since the check to validate filename case
+	// for Gopkg filenames is not relevant to case-sensitive filesystems like
+	// ext4(linux), try for an early return.
 	caseSensitive, err := fs.IsCaseSensitiveFilesystem(projectRoot)
 	if err != nil {
 		return errors.Wrap(err, "could not check validity of configuration filenames")

project_test.go

@@ -63,7 +63,13 @@ func TestFindRoot(t *testing.T) {
 	}
 }
 
-func TestCheckCfgFilenames(t *testing.T) {
+func TestCheckGopkgFilenames(t *testing.T) {
+	// We are trying to skip this test on file systems which are case-sensiive. We could
+	// have used `fs.IsCaseSensitiveFilesystem` for this check. However, the code we are
+	// testing also relies on `fs.IsCaseSensitiveFilesystem`. So a bug in
+	// `fs.IsCaseSensitiveFilesystem` could prevent this test from being run. This is the
+	// only scenario where we prefer the OS heuristic over doing the actual work of
+	// validating filesystem case sensitivity via `fs.IsCaseSensitiveFilesystem`.
 	if runtime.GOOS != "windows" && runtime.GOOS != "darwin" {
 		t.Skip("skip this test on non-Windows, non-macOS")
 	}
@@ -111,11 +117,11 @@ func TestCheckCfgFilenames(t *testing.T) {
 		tmpPath := h.Path(".")
 
 		// Create any files that are needed for the test before invoking
-		// `checkCfgFilenames`.
+		// `checkGopkgFilenames`.
 		for _, file := range c.createFiles {
 			h.TempFile(file, "")
 		}
-		err := checkCfgFilenames(tmpPath)
+		err := checkGopkgFilenames(tmpPath)
 
 		if c.wantErr {
 			if err == nil {