Go API tests

Use the pgmemtest.Fixture setup from unit tests. fx.ShadowPG(t) creates a fresh fork and sets DATABASE_URL plus libpq’s PG* connection variables for the test. Construct the application after this call so its normal database setup reads the temporary values.

api_test.go

func TestCreateOrderAPI(t *testing.T) {
  fx.ShadowPG(t)

  app, err := NewApp() // unchanged code; reads its normal DATABASE_URL
  if err != nil { t.Fatal(err) }
  t.Cleanup(func() { app.Close() })
  server := httptest.NewServer(app.Handler())
  t.Cleanup(server.Close)

  body := strings.NewReader(`{"sku":"book"}`)
  resp, err := server.Client().Post(server.URL+"/orders", "application/json", body)
  if err != nil { t.Fatal(err) }
  defer resp.Body.Close()
  if resp.StatusCode != http.StatusCreated {
    t.Fatalf("status = %d", resp.StatusCode)
  }
}

Import net/http, net/http/httptest, strings, and testing in this example. The application constructor, handler, and close method stand for your existing API. Each test receives a new copy of the schema and seed data prepared in TestMain. For an app that reads a different DSN variable, pass pgmemtest.ShadowOptions{ExtraEnv: []string{"APP_DATABASE_URL"}}.

The environment is process-wide, so tests using ShadowPG cannot use t.Parallel(). Construct and close each app inside its test. A pool created before ShadowPG keeps its earlier connection settings. For parallel tests, inject fx.DB(t) or fx.PgxPool(t) into an app factory that accepts a handle.

Safe parallel execution

With ShadowPG, run API cases sequentially inside each package test process. Run different packages concurrently with go test -p 4 ./...; each process creates its own fixture and app. For multiple workers on one package, use separate go test -run ... -count=1 processes with disjoint cases. Give every process its own app and listening port. -parallel 1 is not a workaround for t.Parallel() because ShadowPG calls t.Setenv. If methods in one process must run in parallel, use a separate httptest.Server, fork, and injected fx.DB(t) or fx.PgxPool(t) per test instead.