How to mock outbound HTTP traffic in Go using `httptest`

status_test.go

func TestGetStatus_ReturnsActiveStatus(t *testing.T) {
	// Arrange a test HTTP server on a dynamically assigned port.
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		fmt.Fprintln(w, `{"results":[{"status":"active"}]}`)
	}))
	defer ts.Close()

	// Creates an HTTP client configured to interact with the test server.
	client := Client{
		client: ts.Client(),
		url:    ts.URL,
	}

	// Act
	status, err := GetStatus(&client)
	if err != nil {
		t.Fatalf("Expected no error, got: %v", err)
	}

	// Assert
	if status != "active" {
		t.Errorf("Expected 'active', got: %s", status)
	}
}