feat: look for config file in .config subdirectory

cmd/root.go

@@ -132,7 +132,7 @@ func runE(v *viper.Viper, statz *stats.Stats, cmd *cobra.Command, args []string)
 		configFile = os.Getenv("TREEFMT_CONFIG")
 	}
 
-	filenames := []string{"treefmt.toml", ".treefmt.toml"}
+	filenames := []string{"treefmt.toml", ".treefmt.toml", ".config/treefmt.toml"}
 
 	// look in PRJ_ROOT if set
 	if prjRoot := os.Getenv("PRJ_ROOT"); configFile == "" && prjRoot != "" {

cmd/root_test.go

@@ -589,6 +589,78 @@ func TestConfigFile(t *testing.T) {
 	}
 }
 
+func TestDotConfigDir(t *testing.T) {
+	t.Run("basic", func(t *testing.T) {
+		as := require.New(t)
+
+		tempDir := test.TempExamples(t)
+
+		// remove the sample treefmt.toml
+		as.NoError(os.Remove(filepath.Join(tempDir, "treefmt.toml")), "failed to remove sample treefmt.toml")
+
+		// ensure the test config is created in the .config subdirectory
+		configPath := filepath.Join(tempDir, ".config/treefmt.toml")
+
+		// ensure we are executing from the root of the temp dir
+		test.ChangeWorkDir(t, tempDir)
+
+		treefmt(t,
+			withConfig(configPath, &config.Config{
+				FormatterConfigs: map[string]*config.Formatter{
+					"echo": {
+						Command:  "echo",
+						Includes: []string{"*"},
+					},
+				},
+			}),
+			withNoError(t),
+			withStats(t, map[stats.Type]int{
+				stats.Traversed: 33,
+				stats.Matched:   33,
+				stats.Formatted: 33,
+				stats.Changed:   0,
+			}),
+		)
+	})
+
+	t.Run("project root ending in .config", func(t *testing.T) {
+		as := require.New(t)
+
+		// create a project root whose name ends with .config
+		tempDir := filepath.Join(t.TempDir(), "foo.config")
+		as.NoError(os.Mkdir(tempDir, 0o755))
+
+		test.TempExamplesInDir(t, tempDir)
+
+		// remove the sample treefmt.toml
+		as.NoError(os.Remove(filepath.Join(tempDir, "treefmt.toml")), "failed to remove sample treefmt.toml")
+
+		// place config in the .config subdirectory
+		configPath := filepath.Join(tempDir, ".config/treefmt.toml")
+
+		// ensure we are executing from the root of the temp dir
+		test.ChangeWorkDir(t, tempDir)
+
+		treefmt(t,
+			withConfig(configPath, &config.Config{
+				FormatterConfigs: map[string]*config.Formatter{
+					"echo": {
+						Command:  "echo",
+						Includes: []string{"*"},
+					},
+				},
+			}),
+			withNoError(t),
+			withStats(t, map[stats.Type]int{
+				stats.Traversed: 33,
+				stats.Matched:   33,
+				stats.Formatted: 33,
+				stats.Changed:   0,
+			}),
+		)
+	})
+}
+
 func TestCache(t *testing.T) {
 	tempDir := test.TempExamples(t)
 	configPath := filepath.Join(tempDir, "treefmt.toml")

config/config.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"os"
 	"os/exec"
+	"path"
 	"path/filepath"
 	"regexp"
 	"slices"
@@ -356,6 +357,11 @@ func determineTreeRoot(v *viper.Viper, cfg *Config, logger *log.Logger) error {
 			)
 
 			cfg.TreeRoot = filepath.Dir(v.ConfigFileUsed())
+
+			// if the config file was located inside a `.config` directory, we need to go up one level
+			if path.Base(cfg.TreeRoot) == ".config" {
+				cfg.TreeRoot = filepath.Dir(cfg.TreeRoot)
+			}
 		}
 	}
 

test/test.go

@@ -38,6 +38,12 @@ func WriteConfig(t *testing.T, path string, cfg *config.Config) {
 		t.Fatalf("failed to stat old config file: %v", path)
 	}
 
+	// ensure any sub directories exist
+	err = os.MkdirAll(filepath.Dir(path), 0o755)
+	if err != nil {
+		t.Fatalf("failed to ensure sub directories for config file: %v", err)
+	}
+
 	f, err := os.Create(path)
 	if err != nil {
 		t.Fatalf("failed to create a new config file: %v", err)