Configuration path can come from environment.

This adds support for using the GH_CONFIG_DIR environment variable to determine
where the config files are written, this is useful for cases where the homedir
is not writable.

internal/config/config_file.go

@@ -14,6 +14,10 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+const (
+	GH_CONFIG_DIR = "GH_CONFIG_DIR"
+)
+
 func ConfigDir() string {
 	homeDir, _ := homeDirAutoMigrate()
 	return homeDir
@@ -263,3 +267,10 @@ func findRegularFile(p string) string {
 	}
 	return ""
 }
+
+func configPath() string {
+	if v := os.Getenv(GH_CONFIG_DIR); v != "" {
+		return v
+	}
+	return "~/.config/gh"
+}

internal/config/config_file_test.go

@@ -3,6 +3,7 @@ package config
 import (
 	"bytes"
 	"fmt"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -146,3 +147,23 @@ func Test_parseConfigFile(t *testing.T) {
 		})
 	}
 }
+
+func Test_configPath(t *testing.T) {
+	tests := []struct {
+		envVar string
+		want   string
+	}{
+		{"/tmp/gh", "/tmp/gh"},
+		{"", "~/.config/gh"},
+	}
+
+	for _, tt := range tests {
+		t.Run(fmt.Sprintf("envVar: %q", tt.envVar), func(t *testing.T) {
+			if tt.envVar != "" {
+				os.Setenv(GH_CONFIG_DIR, tt.envVar)
+				defer os.Unsetenv(GH_CONFIG_DIR)
+			}
+			eq(t, configPath(), tt.want)
+		})
+	}
+}