extension: split out an async specific broker for "after" events (#346)

Signed-off-by: James Hillyerd <james@hillyerd.com>

pkg/extension/async_broker_test.go

@@ -0,0 +1,101 @@
+package extension_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/inbucket/inbucket/pkg/extension"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// Simple smoke test without using AsyncTestListener.
+func TestAsyncBrokerEmitCallsOneListener(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listener.
+	events := make(chan string, 1)
+	listener := func(s string) {
+		events <- s
+	}
+	broker.AddListener("x", listener)
+
+	want := "bacon"
+	broker.Emit(&want)
+
+	var got string
+	select {
+	case event := <-events:
+		got = event
+
+	case <-time.After(time.Second * 2):
+		t.Fatal("Timeout waiting for event")
+	}
+
+	if got != want {
+		t.Errorf("Emit got %q, want %q", got, want)
+	}
+}
+
+func TestAsyncBrokerEmitCallsMultipleListeners(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listeners.
+	first := broker.AsyncTestListener("first", 1)
+	second := broker.AsyncTestListener("second", 1)
+
+	want := "hi"
+	broker.Emit(&want)
+
+	first_got, err := first()
+	require.NoError(t, err)
+	assert.Equal(t, want, *first_got)
+
+	second_got, err := second()
+	require.NoError(t, err)
+	assert.Equal(t, want, *second_got)
+}
+
+func TestAsyncBrokerAddingDuplicateNameReplacesPrevious(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listeners.
+	first := broker.AsyncTestListener("dup", 1)
+	second := broker.AsyncTestListener("dup", 1)
+
+	want := "hi"
+	broker.Emit(&want)
+
+	first_got, err := first()
+	require.Error(t, err)
+	assert.Nil(t, first_got)
+
+	second_got, err := second()
+	require.NoError(t, err)
+	assert.Equal(t, want, *second_got)
+}
+
+func TestAsyncBrokerRemovingListenerSuccessful(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+
+	// Setup listeners.
+	first := broker.AsyncTestListener("1", 1)
+	second := broker.AsyncTestListener("2", 1)
+	broker.RemoveListener("1")
+
+	want := "hi"
+	broker.Emit(&want)
+
+	first_got, err := first()
+	require.Error(t, err)
+	assert.Nil(t, first_got)
+
+	second_got, err := second()
+	require.NoError(t, err)
+	assert.Equal(t, want, *second_got)
+}
+
+func TestAsyncBrokerRemovingMissingListener(t *testing.T) {
+	broker := &extension.AsyncEventBroker[string]{}
+	broker.RemoveListener("doesn't crash")
+}