fix volume case issue in windows platform (hashicorp#199)

* fix volume case issue in windows platform

* update

* add test case

internal/terraform/rootmodule/path.go

@@ -0,0 +1,12 @@
+package rootmodule
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+func pathEquals(path1, path2 string) bool {
+	volume1 := filepath.VolumeName(path1)
+	volume2 := filepath.VolumeName(path2)
+	return strings.EqualFold(volume1, volume2) && path1[len(volume1):] == path2[len(volume2):]
+}

internal/terraform/rootmodule/path_unix_test.go

@@ -0,0 +1,39 @@
+// +build !windows
+
+package rootmodule
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestPathEquals(t *testing.T) {
+	testCases := []struct {
+		name     string
+		path1    string
+		path2    string
+		expected bool
+	}{
+		{
+			"path the same",
+			`/home/user/documents/tf`,
+			`/home/user/documents/tf`,
+			true,
+		},
+		{
+			"path case not the same",
+			`/home/user/documents/tf`,
+			`/Home/user/documents/tf`,
+			false,
+		},
+	}
+
+	for i, tc := range testCases {
+		t.Run(fmt.Sprintf("%d-%s", i, tc.name), func(t *testing.T) {
+			result := pathEquals(tc.path1, tc.path2)
+			if result != tc.expected {
+				t.Fatalf("expected: %t Got: %t", tc.expected, result)
+			}
+		})
+	}
+}

internal/terraform/rootmodule/path_windows_test.go

@@ -0,0 +1,49 @@
+package rootmodule
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestPathEquals(t *testing.T) {
+	testCases := []struct {
+		name     string
+		path1    string
+		path2    string
+		expected bool
+	}{
+		{
+			"file path the same",
+			`c:\Users\user\Documents\tf`,
+			`c:\Users\user\Documents\tf`,
+			true,
+		},
+		{
+			"volume case insensitive",
+			`c:\Users\user\Documents\tf`,
+			`C:\Users\user\Documents\tf`,
+			true,
+		},
+		{
+			"path folder case different",
+			`c:\Users\user\Documents\tf`,
+			`c:\Users\user\documents\tf`,
+			false,
+		},
+		{
+			"file path different",
+			`c:\Users\user\Documents\tf`,
+			`c:\Users\user\Documents\tf\test`,
+			false,
+		},
+	}
+
+	for i, tc := range testCases {
+		t.Run(fmt.Sprintf("%d-%s", i, tc.name), func(t *testing.T) {
+			result := pathEquals(tc.path1, tc.path2)
+			if result != tc.expected {
+				t.Fatalf("expected: %t Got: %t", tc.expected, result)
+			}
+		})
+	}
+}

internal/terraform/rootmodule/root_module.go

@@ -262,8 +262,8 @@ func (rm *rootModule) ReferencesModulePath(path string) bool {
 			continue
 		}
 		absPath := filepath.Join(rm.moduleManifest.rootDir, m.Dir)
-		rm.logger.Printf("checking if %q == %q", absPath, path)
-		if absPath == path {
+		rm.logger.Printf("checking if %q equals %q", absPath, path)
+		if pathEquals(absPath, path) {
 			return true
 		}
 	}
@@ -310,7 +310,7 @@ func (rm *rootModule) IsKnownModuleManifestFile(path string) bool {
 		return false
 	}
 
-	return rm.moduleManifestFile.Path() == path
+	return pathEquals(rm.moduleManifestFile.Path(), path)
 }
 
 func (rm *rootModule) IsKnownPluginLockFile(path string) bool {
@@ -321,5 +321,5 @@ func (rm *rootModule) IsKnownPluginLockFile(path string) bool {
 		return false
 	}
 
-	return rm.pluginLockFile.Path() == path
+	return pathEquals(rm.pluginLockFile.Path(), path)
 }

internal/terraform/rootmodule/root_module_manager.go

@@ -92,7 +92,7 @@ func (rmm *rootModuleManager) AddRootModule(dir string) error {
 
 func (rmm *rootModuleManager) exists(dir string) bool {
 	for _, rm := range rmm.rms {
-		if rm.Path() == dir {
+		if pathEquals(rm.Path(), dir) {
 			return true
 		}
 	}
@@ -101,7 +101,7 @@ func (rmm *rootModuleManager) exists(dir string) bool {
 
 func (rmm *rootModuleManager) rootModuleByPath(dir string) *rootModule {
 	for _, rm := range rmm.rms {
-		if rm.Path() == dir {
+		if pathEquals(rm.Path(), dir) {
 			return rm
 		}
 	}