Allow account client auth with environment variables when no .databrickscfg file present (#1097)

## Changes
Allow account client auth with environment variables when no
.databrickscfg file present

Makes the behaviour to be in line with WorkspaceClient auth.
## Tests
Added regression test

cmd/root/auth.go

@@ -83,12 +83,14 @@ func MustAccountClient(cmd *cobra.Command, args []string) error {
 		// 2. 99% of admins will have access to just one account
 		// hence, we don't need to create a special "DEFAULT_ACCOUNT" profile yet
 		_, profiles, err := databrickscfg.LoadProfiles(cmd.Context(), databrickscfg.MatchAccountProfiles)
-		if err != nil {
-			return err
-		}
-		if len(profiles) == 1 {
+		if err == nil && len(profiles) == 1 {
 			cfg.Profile = profiles[0].Name
 		}
+
+		// if there is no config file, we don't want to fail and instead just skip it
+		if err != nil && !errors.Is(err, databrickscfg.ErrNoConfiguration) {
+			return err
+		}
 	}
 
 	allowPrompt := !hasProfileFlag && !shouldSkipPrompt(cmd.Context())

cmd/root/auth_test.go

@@ -181,3 +181,51 @@ func TestWorkspaceClientOrPrompt(t *testing.T) {
 		})
 	})
 }
+
+func TestMustAccountClientWorksWithDatabricksCfg(t *testing.T) {
+	testutil.CleanupEnvironment(t)
+
+	dir := t.TempDir()
+	configFile := filepath.Join(dir, ".databrickscfg")
+	err := os.WriteFile(
+		configFile,
+		[]byte(`
+			[account-1111]
+			host = https://accounts.azuredatabricks.net/
+			account_id = 1111
+			token = foobar
+			`),
+		0755)
+	require.NoError(t, err)
+
+	cmd := New(context.Background())
+
+	t.Setenv("DATABRICKS_CONFIG_FILE", configFile)
+	err = MustAccountClient(cmd, []string{})
+	require.NoError(t, err)
+}
+
+func TestMustAccountClientWorksWithNoDatabricksCfgButEnvironmentVariables(t *testing.T) {
+	testutil.CleanupEnvironment(t)
+
+	ctx, tt := cmdio.SetupTest(context.Background())
+	t.Cleanup(tt.Done)
+	cmd := New(ctx)
+	t.Setenv("DATABRICKS_HOST", "https://accounts.azuredatabricks.net/")
+	t.Setenv("DATABRICKS_TOKEN", "foobar")
+	t.Setenv("DATABRICKS_ACCOUNT_ID", "1111")
+
+	err := MustAccountClient(cmd, []string{})
+	require.NoError(t, err)
+}
+
+func TestMustAccountClientErrorsWithNoDatabricksCfg(t *testing.T) {
+	testutil.CleanupEnvironment(t)
+
+	ctx, tt := cmdio.SetupTest(context.Background())
+	t.Cleanup(tt.Done)
+	cmd := New(ctx)
+
+	err := MustAccountClient(cmd, []string{})
+	require.ErrorContains(t, err, "no configuration file found at")
+}