Testing Chi Routes with Path Variables: Troubleshooting and Solutions

In go-chi, path variable access within routes is facilitated by middleware functions like ArticleCtx. When testing such routes, it's essential to set the path variable in the HTTP request's context manually. This is because the context is not populated automatically by the httptest package.

Problem:
To test a route that utilizes path variables, a test request is created using httptest.NewRequest. However, executing the ArticleCtx middleware during the test returns an HTTP error (Unprocessable Entity), indicating that the path variable context is not available.

Solution:
The solution lies in manually adding the path parameter to the request context before passing it to the handler:

// Create a context with the path variable
req := httptest.NewRequest("GET", "/articles/1", nil)
rctx := chi.NewRouteContext()
rctx.URLParams.Add("articleID", "1")

// Set the RouteCtx in the request context
req = req.WithContext(context.WithValue(req.Context(), chi.RouteCtxKey, rctx))

// Execute the handler with the modified request
rec := httptest.NewRecorder()
ArticleCtx(http.HandlerFunc(GetArticleID)).ServeHTTP(rec, req)

By adding the path variable to the request's context, the ArticleCtx middleware can correctly retrieve the article ID, resolving the Unprocessable Entity error.

Additional Best Practices:

• Consider a testing framework like testify for simplified unit testing.
• Use the httptest.NewRecorder() method to capture the response written by the handler under test.
• Ensure that the expected and actual response bodies match for successful tests.
• Implement additional tests to cover various scenarios, such as handling bad requests or route-level errors.