main_test.go

package main

import (
	"fmt"
	"io"
	"net/http"
	"testing"

	"github.com/ory/dockertest/v3"
	"github.com/stretchr/testify/require"
)

// The tests in this suite check if the business requirements
// have been satisfied. Each test checks a single requirement.

// Every test in this suite is isolated from all other tests,
// there is no data or container instances shared at all.

// Beware, that by default HTTP client does not set a timeout.
// In tests, however, this isn't an issue because the tests *do*
// have a timeout, which defaults to 10 minutes, but can be reduced
// via a command-line parameter.

// After a container has started, there is some time required before
// the application inside it is ready to service the incoming requests.
// This creates a race condition with the test. To avoid this, the tests
// retry with exponential back-off.

// Requirement 1: The application response must contain a heart ("<3")
func TestRespondsWithLove(t *testing.T) {

	pool, err := dockertest.NewPool("")
	require.NoError(t, err, "could not connect to Docker")

	resource, err := pool.Run("docker-gs-ping", "latest", []string{})
	require.NoError(t, err, "could not start container")

	t.Cleanup(func() {
		require.NoError(t, pool.Purge(resource), "failed to remove container")
	})

	var resp *http.Response

	err = pool.Retry(func() error {
		resp, err = http.Get(fmt.Sprint("http://localhost:", resource.GetPort("8080/tcp"), "/"))
		if err != nil {
			t.Log("container not ready, waiting...")
			return err
		}
		return nil
	})
	require.NoError(t, err, "HTTP error")
	defer resp.Body.Close()

	require.Equal(t, http.StatusOK, resp.StatusCode, "HTTP status code")

	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err, "failed to read HTTP body")

	// Finally, test the business requirement!
	require.Contains(t, string(body), "<3", "does not respond with love?")
}

// Requirement 2: The application must include a health-check end-point at /ping,
// responding with JSON document { "Status": "OK" } if everything is well.
func TestHealthCheck(t *testing.T) {

	pool, err := dockertest.NewPool("")
	require.NoError(t, err, "could not connect to Docker")

	resource, err := pool.Run("docker-gs-ping", "latest", []string{})
	require.NoError(t, err, "could not start container")

	t.Cleanup(func() {
		require.NoError(t, pool.Purge(resource), "failed to remove container")
	})

	var resp *http.Response

	err = pool.Retry(func() error {
		resp, err = http.Get(fmt.Sprint("http://localhost:", resource.GetPort("8080/tcp"), "/ping"))
		if err != nil {
			t.Log("container not ready, waiting...")
			return err
		}
		return nil
	})
	require.NoError(t, err, "HTTP error")
	defer resp.Body.Close()

	require.Equal(t, http.StatusOK, resp.StatusCode, "HTTP status code")

	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err, "failed to read HTTP body")

	// Finally, test the business requirement!
	require.JSONEq(t, `{"Status":"OK"}`, string(body), "does not respond with valid JSON?")
}