From e4f021dd420b138947db4ec2a3e9ddd24720c795 Mon Sep 17 00:00:00 2001
From: Joseph Phillips <joe.phillips@canonical.com>
Date: Thu, 28 Nov 2024 11:41:08 +0100
Subject: [PATCH] fix: remove possibility of zero-effect Stop from api watcher
 test

This handles a situation where we may be entrant into the eventCh case in
the call to Next when Stop is called. In that case, the default clause
will be invoked and we effectively ignore the stop call. This means the
watcher will never stop, causing test failure.
---
 api/watcher/watcher_test.go | 41 +++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 18 deletions(-)

diff --git a/api/watcher/watcher_test.go b/api/watcher/watcher_test.go
index 11862e71868..1a84fd4e079 100644
--- a/api/watcher/watcher_test.go
+++ b/api/watcher/watcher_test.go
@@ -100,26 +100,31 @@ func setupWatcher[T any](c *gc.C, caller *apimocks.MockAPICaller, facadeName str
 	eventCh := make(chan T)
 
 	stopped := make(chan bool)
-	caller.EXPECT().APICall(gomock.Any(), facadeName, 666, "id-666", "Stop", nil, gomock.Any()).DoAndReturn(func(_ context.Context, _ string, _ int, _ string, _ string, _ any, _ any) error {
-		select {
-		case stopped <- true:
-		default:
-		}
-		return nil
-	}).Return(nil).AnyTimes()
-
-	caller.EXPECT().APICall(gomock.Any(), facadeName, 666, "id-666", "Next", nil, gomock.Any()).DoAndReturn(func(_ context.Context, _ string, _ int, _ string, _ string, _ any, r any) error {
-		select {
-		case ev, ok := <-eventCh:
-			if !ok {
-				c.FailNow()
+	caller.EXPECT().APICall(gomock.Any(), facadeName, 666, "id-666", "Stop", nil, gomock.Any()).DoAndReturn(
+		func(context.Context, string, int, string, string, any, any) error {
+			select {
+			case stopped <- true:
+			case <-time.After(testing.LongWait):
+				c.Fatalf("timed out waiting for stop call")
 			}
-			*(*r.(*any)).(*any) = ev
 			return nil
-		case <-stopped:
-		}
-		return &params.Error{Code: params.CodeStopped}
-	}).AnyTimes()
+		},
+	).Return(nil).AnyTimes()
+
+	caller.EXPECT().APICall(gomock.Any(), facadeName, 666, "id-666", "Next", nil, gomock.Any()).DoAndReturn(
+		func(_ context.Context, _ string, _ int, _ string, _ string, _ any, r any) error {
+			select {
+			case ev, ok := <-eventCh:
+				if !ok {
+					c.Fatalf("next channel closed")
+				}
+				*(*r.(*any)).(*any) = ev
+				return nil
+			case <-stopped:
+			}
+			return &params.Error{Code: params.CodeStopped}
+		},
+	).AnyTimes()
 	return "id-666", eventCh
 }