Implement the functional options pattern

Author: tt

cmd/mcptools/commands/test_helpers.go

@@ -30,7 +30,7 @@ func setupMockClient(executeFunc func(method string, _ any) (map[string]any, err
 	mockClient := client.NewWithTransport(mockTransport)
 
 	// Override the function that creates clients
-	CreateClientFunc = func(_ []string) (*client.Client, error) {
+	CreateClientFunc = func(_ []string, _ ...client.Option) (*client.Client, error) {
 		return mockClient, nil
 	}
 

cmd/mcptools/commands/utils.go

@@ -17,7 +17,7 @@ var (
 
 // CreateClientFunc is the function used to create MCP clients.
 // This can be replaced in tests to use a mock transport.
-var CreateClientFunc = func(args []string) (*client.Client, error) {
+var CreateClientFunc = func(args []string, opts ...client.Option) (*client.Client, error) {
 	if len(args) == 0 {
 		return nil, ErrCommandRequired
 	}
@@ -42,7 +42,13 @@ var CreateClientFunc = func(args []string) (*client.Client, error) {
 		return client.NewHTTP(args[0]), nil
 	}
 
-	return client.NewStdio(args), nil
+	c := client.NewStdio(args)
+
+	for _, opt := range opts {
+		opt(c)
+	}
+
+	return c, nil
 }
 
 // ProcessFlags processes command line flags, sets the format option, and returns the remaining

pkg/client/client.go

@@ -18,6 +18,10 @@ type Client struct {
 	transport transport.Transport
 }
 
+// Option provides a way for passing options to the Client to change its
+// configuration.
+type Option func(*Client)
+
 // NewWithTransport creates a new MCP client using the provided transport.
 // This allows callers to provide a custom transport implementation.
 func NewWithTransport(t transport.Transport) *Client {