fix(web): run automatic actions after a repository rescan

The rescan button of one repository now triggers automatic actions too. The webhook calls run in the background so the response does not wait for them.

README.md

@@ -96,7 +96,7 @@ actions:
 
 ### Automatic actions
 
-An action with `auto: true` fires without a click. After every scan, and once at startup, the server sends the webhook for each current alert whose kind is in `kinds`. It sends once per action, repo, alert URL and head commit. A new commit on a pull request is a new send.
+An action with `auto: true` fires without a click. After every scan, after every single-repository rescan, and once at startup, the server sends the webhook for each current alert whose kind is in `kinds`. It sends once per action, repo, alert URL and head commit. A new commit on a pull request is a new send.
 
 ```yaml
 actions:

internal/collector/collector.go

@@ -119,10 +119,13 @@ func (c *Collector) OnRefresh(fn func(context.Context, View)) { c.onRefresh = ap
 
 func (c *Collector) refreshAndNotify(ctx context.Context) {
 	c.Refresh(ctx)
-	if len(c.onRefresh) == 0 || ctx.Err() != nil {
+	if ctx.Err() != nil {
 		return
 	}
-	v := c.View()
+	c.notify(ctx, c.View())
+}
+
+func (c *Collector) notify(ctx context.Context, v View) {
 	for _, fn := range c.onRefresh {
 		fn(ctx, v)
 	}
@@ -239,7 +242,12 @@ func (c *Collector) RefreshRepo(ctx context.Context, name string) (View, error)
 	c.mu.Lock()
 	c.repos[canon] = r
 	c.mu.Unlock()
-	return c.View(), nil
+	v := c.View()
+	if len(c.onRefresh) > 0 {
+		// The request context ends with the response, which must not wait for webhooks.
+		go c.notify(context.WithoutCancel(ctx), v)
+	}
+	return v, nil
 }
 
 func (c *Collector) configured(name string) (string, bool) {

internal/collector/collector_test.go

@@ -519,3 +519,37 @@ func TestPROpenDoesNotChangeCounts(t *testing.T) {
 		t.Fatalf("view = %+v", v)
 	}
 }
+
+func TestRefreshRepoRunsRefreshHooksWithTheNewView(t *testing.T) {
+	f := &fakeFetcher{fn: func(name string) (model.Repo, error) {
+		return model.Repo{FullName: name, URL: "u", Issues: make([]model.Issue, 3)}, nil
+	}}
+	c := newCollector(f, "o/a")
+	got := make(chan View, 1)
+	c.OnRefresh(func(_ context.Context, v View) { got <- v })
+	if _, err := c.RefreshRepo(context.Background(), "o/a"); err != nil {
+		t.Fatal(err)
+	}
+	select {
+	case v := <-got:
+		if len(v.Repos) != 1 || len(v.Repos[0].Issues) != 3 {
+			t.Fatalf("hook saw a stale view: %+v", v.Repos)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("refresh hook did not run after a repository refresh")
+	}
+}
+
+func TestRefreshRepoFailureSkipsRefreshHooks(t *testing.T) {
+	c := newCollector(&fakeFetcher{fn: func(string) (model.Repo, error) { return model.Repo{}, errors.New("nope") }}, "o/a")
+	called := make(chan struct{}, 1)
+	c.OnRefresh(func(context.Context, View) { called <- struct{}{} })
+	if _, err := c.RefreshRepo(context.Background(), "unknown/x"); err == nil {
+		t.Fatal("unknown repository must fail")
+	}
+	select {
+	case <-called:
+		t.Fatal("hook ran for a refused refresh")
+	case <-time.After(200 * time.Millisecond):
+	}
+}