Add a scenario about handling concurrent fetches

Relates-to #211

It's debatable whether this deserves to be surfaced in an acceptance
test, but I'm not sure yet which layer is the right place to solve this,
so it makes sense to put it in our full-stack tests in any case. And
it's probably useful to document this capabilty.

doc/features/fetch_after_connection.feature

@@ -1,4 +1,4 @@
-Feature: Fetch after connection
+Feature: Fetch automatically after connection
 
   After a repo is connected, we automatically run a fetch in the
   background.
@@ -7,3 +7,10 @@ Feature: Fetch after connection
     Given a remote repo with commits on the "main" branch
     When a consumer connects the remote repo
     Then the repo should have been fetched
+
+  @wip
+  Scenario: Succesful manual fetch concurrent with automatic background fetch
+    Given a remote repo with commits on the "main" branch
+    When a consumer connects the remote repo
+    And a consumer triggers a manual fetch of the repo
+    Then the repo should have been fetched 2 times

packages/acceptance-tests/src/step_definitions/steps.ts

@@ -235,6 +235,19 @@ Then('the events received by the consumer should be:', function (this: World, ex
   assertThat(this.events, equalTo(expectedEvents.split('\n')))
 })
 
+Then('the repo should have been fetched {int} times', async function (this: World, expectedTimes: number) {
+  for (const _ of new Array(expectedTimes))
+    await promiseThat(
+      new Promise<void>((received) =>
+        this.domainEvents.on('repo.fetched', (event) => event.repoId.equals(this.repoId) && received())
+      ),
+      fulfilled()
+    )
+})
+
+Then('the events received by the consumer should be:', function (this: World, expectedEvents: string) {
+  assertThat(this.events, equalTo(expectedEvents.split('\n')))
+})
 Then('it should respond with {int} status', function (this: World, expectedStatus: number) {
   assertThat(this.lastResponse.status, equalTo(expectedStatus))
 })