step-9-integration-tests-for-api.md

Step 9: Integration tests for the API

In this step we will add integration tests for the API, and for that we are going to use the net/httptest package from the standard library.

The net/httptest package

The net/httptest package provides a set of utilities for HTTP testing. It includes a test server that implements the http.Handler interface, a global Client to make requests to test servers, and various functions to parse HTTP responses.

For the specific use case of Gin, we are going to follow its official documentation.

Testing the HTTP endpoints

For that, we are going to create a new file called router_test.go inside the internal/app package. Please add the following content:

package app_test

import (
	"bytes"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/testcontainers/workshop-go/internal/app"
)

func TestRoutesFailBecauseDependenciesAreNotStarted(t *testing.T) {
	router := app.SetupRouter()

	t.Run("GET /ratings fails", func(t *testing.T) {
		w := httptest.NewRecorder()
		req, err := http.NewRequest("GET", "/ratings?talkId=testcontainers-integration-testing", nil)
		require.NoError(t, err)
		router.ServeHTTP(w, req)

		// we are receiving a 500 because the ratings repository is not started
		assert.Equal(t, http.StatusInternalServerError, w.Code)
	})

	t.Run("POST /ratings fails", func(t *testing.T) {
		body := []byte(`{"talkId":"testcontainers-integration-testing","value":5}`)

		w := httptest.NewRecorder()
		req, err := http.NewRequest("POST", "/ratings", bytes.NewReader(body))
		require.NoError(t, err)

		// we need to set the content type header because we are sending a body
		req.Header.Add("Content-Type", "application/json")

		router.ServeHTTP(w, req)

		// we are receiving a 500 because the ratings repository is not started
		assert.Equal(t, http.StatusInternalServerError, w.Code)
	})
}

Let's check what we are doing here:

• We are setting up the Gin's router, with the app.SetupRouter function.
• a new httptest.Recorder is used to record the response.
• each subtest defines a new http.Request, with the right method and path.
• the ServeHTTP method on the router is called with the httptest.Recorder and the http.Request.
• the TestRoutesFailBecauseDependenciesAreNotStarted test method is verifying that the routes that depend on the repositories are failing with a 500 Internal Server error response code. That's because the runtime dependencies are not started for this test.

Let's run the test:

go test -v -count=1 ./internal/app -run TestRoutesFailBecauseDependenciesAreNotStarted
=== RUN   TestRoutesFailBecauseDependenciesAreNotStarted
[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /                         --> github.com/testcontainers/workshop-go/internal/app.Root (3 handlers)
[GIN-debug] GET    /ratings                  --> github.com/testcontainers/workshop-go/internal/app.Ratings (3 handlers)
[GIN-debug] POST   /ratings                  --> github.com/testcontainers/workshop-go/internal/app.AddRating (3 handlers)
=== RUN   TestRoutesFailBecauseDependenciesAreNotStarted/GET_/ratings_fails
Unable to connect to database: failed to connect to `host=/private/tmp user=mdelapenya database=`: dial error (dial unix /private/tmp/.s.PGSQL.5432: connect: no such file or directory)
[GIN] 2023/10/30 - 14:29:12 | 500 |    3.623292ms |                 | GET      "/ratings?talkId=testcontainers-integration-testing"
=== RUN   TestRoutesFailBecauseDependenciesAreNotStarted/POST_/ratings_fails
Unable to connect to database: failed to connect to `host=/private/tmp user=mdelapenya database=`: dial error (dial unix /private/tmp/.s.PGSQL.5432: connect: no such file or directory)
[GIN] 2023/10/30 - 14:29:12 | 500 |     105.791µs |                 | POST     "/ratings"
--- PASS: TestRoutesFailBecauseDependenciesAreNotStarted (0.00s)
    --- PASS: TestRoutesFailBecauseDependenciesAreNotStarted/GET_/ratings_fails (0.00s)
    --- PASS: TestRoutesFailBecauseDependenciesAreNotStarted/POST_/ratings_fails (0.00s)
PASS
ok      github.com/testcontainers/workshop-go/internal/app      0.308

This unit test is not very useful, but it is a good starting point to understand how to test the HTTP endpoints.

Next: E2E tests with real dependencies