inanzzz | Using regex placeholders in Golang unit tests

If you don't know what exact data you are asserting in Golang unit tests, you can use a regex pattern placeholder as shown below. This example expects a numeric ID data as part of response body but we don't know what it is so using ID_REGEX as placeholder.

Example

package league

import (
	"bytes"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"github.com/stretchr/testify/assert"
)

func TestCreate(t *testing.T) {
	// Some other code.

	requestBody := `
{
 "name": "Premier League"
}
`

	responseBody := `
{
 "operation": "leagues_post",
 "data": {
   "id": ID_REGEX
 }
}
`

	rq := httptest.NewRequest(http.MethodPost, "/leagues", strings.NewReader(requestBody))
	rw := httptest.NewRecorder()

	yourHandler.Create(rw, rq)

	// Flatten formatted json string.
	buffer := new(bytes.Buffer)
	_ = json.Compact(buffer, []byte(responseBody))

	// Replace placeholders with corresponding regex patterns.
	expectedBody := strings.ReplaceAll(buffer.String(), "ID_REGEX", "\\d+/g") // Or "\\w+" for strings, or just use ".*?" to match anything

	assert.Regexp(t, expectedBody, rw.Body.String())

	// Some other code.
}