Add service principal flag and handle cmd for .azure dir

- Refactor some common code into method.
- Use `true` as a no-op command when using an existin .azure directory.
- Fix indentation.

pkg/az/login.go

@@ -33,11 +33,16 @@ func (c *LoginCommand) SetAction(action string) {
 }
 
 func (c *LoginCommand) GetCommand() string {
+	if c.azureDirExists() {
+		// Use a no-op command since we don't have to log in.
+		return "true"
+	}
+
 	return "az"
 }
 
 func (c *LoginCommand) GetArguments() []string {
-	if _, err := os.Stat(filepath.Join(os.Getenv("HOME"), ".azure")); err == nil {
+	if c.azureDirExists() {
 		return []string{}
 	}
 	return []string{"login"}
@@ -46,7 +51,7 @@ func (c *LoginCommand) GetArguments() []string {
 func (c *LoginCommand) GetFlags() builder.Flags {
 	flags := builder.Flags{}
 
-	if _, err := os.Stat(filepath.Join(os.Getenv("HOME"), ".azure")); err == nil {
+	if c.azureDirExists() {
 		return flags
 	}
 
@@ -71,3 +76,8 @@ func (c *LoginCommand) GetFlags() builder.Flags {
 func (c *LoginCommand) SuppressesOutput() bool {
 	return false
 }
+
+func (c *LoginCommand) azureDirExists() bool {
+	_, err := os.Stat(filepath.Join(os.Getenv("HOME"), ".azure"))
+	return err == nil
+}

pkg/az/login_test.go

@@ -26,7 +26,7 @@ func TestLoginCommand_GetArguments_ServicePrincipal(t *testing.T) {
 	assert.Equal(t, expectedArgs, args)
 }
 
-func TestLoginCommand_GetArguments_ExistingAzureDirectory(t *testing.T) {
+func TestLoginCommand_GetCommandAndGetArguments_ExistingAzureDirectory(t *testing.T) {
 	tempHome := t.TempDir()
 	os.Setenv("HOME", tempHome)
 	homeDir := os.Getenv("HOME")
@@ -37,6 +37,7 @@ func TestLoginCommand_GetArguments_ExistingAzureDirectory(t *testing.T) {
 	args := cmd.GetArguments()
 
 	expectedArgs := []string{}
+	assert.Equal(t, "true", cmd.GetCommand())
 	assert.Equal(t, expectedArgs, args)
 }
 
@@ -68,6 +69,7 @@ func TestLoginCommand_GetFlags_ServicePrincipal(t *testing.T) {
 	flags := cmd.GetFlags()
 
 	expectedFlags := builder.Flags{
+		builder.NewFlag("service-principal", ""),
 		builder.NewFlag("username", "test-client-id"),
 		builder.NewFlag("password", "test-client-secret"),
 		builder.NewFlag("tenant", "test-tenant-id"),
@@ -105,15 +107,15 @@ func TestLoginCommand_GetFlags_SystemManagedIdentity(t *testing.T) {
 }
 
 func TestLoginCommand_GetFlags_ExistingAzureDirectory(t *testing.T) {
-  tempHome := t.TempDir()
-  os.Setenv("HOME", tempHome)
-  homeDir := os.Getenv("HOME")
-  os.MkdirAll(filepath.Join(homeDir, ".azure"), 0755)
-  defer os.RemoveAll(filepath.Join(homeDir, ".azure"))
+	tempHome := t.TempDir()
+	os.Setenv("HOME", tempHome)
+	homeDir := os.Getenv("HOME")
+	os.MkdirAll(filepath.Join(homeDir, ".azure"), 0755)
+	defer os.RemoveAll(filepath.Join(homeDir, ".azure"))
 
-  cmd := &LoginCommand{}
-  flags := cmd.GetFlags()
+	cmd := &LoginCommand{}
+	flags := cmd.GetFlags()
 
-  expectedFlags := builder.Flags{}
-  assert.Equal(t, expectedFlags, flags)
+	expectedFlags := builder.Flags{}
+	assert.Equal(t, expectedFlags, flags)
 }