fix: Handle implicit relative path for config

Fixes #117

internal/cli/config/config.go

@@ -53,6 +53,10 @@ func (c *Config) Read() error {
 
 func (c *Config) Save() error {
 	dir, _ := filepath.Split(c.path)
+	// If dir is empty (e.g., when path is just a filename), use current directory
+	if dir == "" {
+		dir = "."
+	}
 	if err := os.MkdirAll(dir, 0o700); err != nil {
 		return fmt.Errorf("create config directory '%s': %w", dir, err)
 	}

internal/cli/config/config_test.go

@@ -0,0 +1,80 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestConfig_Save(t *testing.T) {
+	t.Parallel()
+
+	// Create a temporary directory for the test
+	tmpDir := t.TempDir()
+
+	// Change to temp directory so relative paths resolve correctly
+	originalDir, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("Failed to get current directory: %v", err)
+	}
+	defer func() {
+		if err := os.Chdir(originalDir); err != nil {
+			t.Logf("Failed to restore original directory: %v", err)
+		}
+	}()
+
+	tests := []struct {
+		name            string
+		configPath      string
+		contextName     string
+		expectFileAt    string // Expected file location for verification
+		useAbsolutePath bool   // Whether to use absolute path for expectFileAt
+	}{
+		{
+			name:        "relative path without prefix",
+			configPath:  "test-config.yaml",
+			contextName: "test",
+		},
+		{
+			name:        "relative path with prefix",
+			configPath:  "./test-config-2.yaml",
+			contextName: "test2",
+		},
+		{
+			name:        "absolute path",
+			configPath:  filepath.Join(tmpDir, "absolute-config.yaml"),
+			contextName: "test3",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			if err := os.Chdir(tmpDir); err != nil {
+				t.Fatalf("Failed to change to temp directory: %v", err)
+			}
+
+			cfg := &Config{
+				CurrentContext: tt.contextName,
+				Contexts: map[string]*Context{
+					tt.contextName: {
+						Name: tt.contextName,
+					},
+				},
+				path: tt.configPath,
+			}
+
+			// This should not fail when saving the config
+			err := cfg.Save()
+			if err != nil {
+				t.Errorf("Expected no error when saving config, got: %v", err)
+			}
+
+			// Verify the file was created
+			if _, err := os.Stat(tt.configPath); os.IsNotExist(err) {
+				t.Errorf("Config file was not created at expected path: %s", tt.configPath)
+			}
+		})
+	}
+}