Make GetPathRelativeTo() resolve symbolic links (#78)

files/paths.go

@@ -68,7 +68,8 @@ func Grep(regex *regexp.Regexp, glob string) (bool, error) {
 	return false, nil
 }
 
-// Return the relative path you would have to take to get from basePath to path
+// GetPathRelativeTo returns the relative path you would have to take to get from basePath to path. If either path
+// or basePath are symbolic links, they will be evaluated before the relative path between them is calculated.
 func GetPathRelativeTo(path string, basePath string) (string, error) {
 	if path == "" {
 		path = "."
@@ -77,12 +78,22 @@ func GetPathRelativeTo(path string, basePath string) (string, error) {
 		basePath = "."
 	}
 
-	inputFolderAbs, err := filepath.Abs(basePath)
+	basePathEvaluated, err := filepath.EvalSymlinks(basePath)
 	if err != nil {
 		return "", errors.WithStackTrace(err)
 	}
 
-	fileAbs, err := filepath.Abs(path)
+	inputFolderAbs, err := filepath.Abs(basePathEvaluated)
+	if err != nil {
+		return "", errors.WithStackTrace(err)
+	}
+
+	pathEvaluated, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		return "", errors.WithStackTrace(err)
+	}
+
+	fileAbs, err := filepath.Abs(pathEvaluated)
 	if err != nil {
 		return "", errors.WithStackTrace(err)
 	}

files/paths_test.go

@@ -1,6 +1,7 @@
 package files
 
 import (
+	"path/filepath"
 	"regexp"
 	"testing"
 
@@ -27,8 +28,12 @@ func TestGetPathRelativeTo(t *testing.T) {
 		{"/root", "/other-root/sub-child/sub-sub-child", "../../../root"},
 	}
 
+	fixtureRoot := "../fixtures/files"
+
 	for _, testCase := range testCases {
-		actual, err := GetPathRelativeTo(testCase.path, testCase.basePath)
+		path := filepath.Join(fixtureRoot, testCase.path)
+		basePath := filepath.Join(fixtureRoot, testCase.basePath)
+		actual, err := GetPathRelativeTo(path, basePath)
 		assert.Nil(t, err, "Unexpected error for path %s and basePath %s: %v", testCase.path, testCase.basePath, err)
 		assert.Equal(t, testCase.expected, actual, "For path %s and basePath %s", testCase.path, testCase.basePath)
 	}