On Mon, Nov 18, 2019 at 10:00 PM Shane H <shane....@gmail.com> wrote:
>
> I'm trying to unit test some code (pasted below). I've struggled to find a
> way to mock the amqp.Connection, so have decided to go the monkey patching
> route.
>
> The test 'works' but only if I use the following incantation
> go test -gcflags=-l
>
> So, my next step is to ensure that -gcflags is set to prevent inlining when
> this test is executed.
> My /thought/ was to check os.Getenv("GO_GCFLAGS"), but as I was kindly
> reminded, executng the tests and compiling the tests are two different things.
> My next brilliant idea was to use a build tag to ensure that the test file is
> only built when the flags are set as I desire. But
> https://golang.org/pkg/go/build/ doesn't offer any ideas where gcflags might
> be checked, or what tag to use.
>
> So, I throw myself at the mercy of golang-nuts to (gently) point me in the
> right direction (I completely understand that there may be an easier way to
> do this, but I cannot see that path)
This is what I usually do in these situations:
var amqpDial=amqp.Dial
func (mq *MQ) Connect() (err error) {
...
mq.conn, err = amqpDial(mq.URI)
...
}
func TestConnect(t *testing.T) {
amqpDial=fakeDial
defer func() {amqpDial=amqp.Dial}()
...
}
>
> ```
> ### Code to test
> // MQ -
> type MQ struct {
> conn *amqp.Connection
> Retry int
> URI string
> }
>
> // Connect -
> func (mq *MQ) Connect() (err error) {
> // Retry MUST be > 0
> if mq.Retry == 0 {
> log.Print("Cannot use a Retry of zero, this process will to default retry to
> 1")
> mq.Retry = 1
> }
>
> // Note: Even though amqp.ParseURI(uri) will validate the URI formed, check
> here that the minimum required exists
> if mq.URI == "" {
> log.Printf("No Message Queue URI configured")
> }
>
> for {
> for i := 0; i < mq.Retry; i++ {
> mq.conn, err = amqp.Dial(mq.URI)
> if err == nil {
> // Successful connection
> log.Printf("Successfully connected to RabbitMQ")
> return nil
> }
> time.Sleep(1 * time.Second)
> }
> // Log that there is a problem connecting to the RabbitMQ service that needs
> urgent attention
> backoff := time.Duration(mq.Retry*rand.Intn(10)) * time.Second
> log.Printf("ALERT: Trouble connecting to RabbitMQ, error: %v, going to
> re-enter retry loop in %s seconds", err, backoff.String())
> time.Sleep(backoff)
> }
> }
>
> ### Test Code
> func TestConnect(t *testing.T) {
> testcases := map[string]struct {
> retry int
> uri string
> err error
> }{
> "Happy Path": {retry: 1, uri: "amqp://localhost:5672/%2f"},
> }
> for name, tc := range testcases {
> t.Run(name, func(t *testing.T) {
> // Monkeypatch amqp to return the nil and the error
> fakeRabbitConnection := func(msg string) (*amqp.Connection, error) {
> return nil, tc.err // I only want the error to have meaning, therefore the
> connection can be nil (which also saves me having to create a mock)
> }
> patch := monkey.Patch(amqp.Dial, fakeRabbitConnection)
> defer patch.Unpatch()
> mq := rabbit.MQ{Retry: tc.retry, URI: tc.uri}
> output := mq.Connect()
> fmt.Println(output) // TODO
> })
> }
> }
> ```
>
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