Only use the most recent check runs on a commit (#823)

This fixes an issue where we would iterate over all check runs on a
commit and keep the last one. Because GitHub returns check runs in
reverse chronological order, this meant we used the oldest result for
each run in the event of duplicates instead of the most recent.

pull/github.go

@@ -819,9 +819,18 @@ func (ghc *GitHubContext) getCheckStatuses() (map[string]string, error) {
 		if err != nil {
 			return nil, errors.Wrapf(err, "failed to get check runs for page %d", opt.Page)
 		}
+
+		// Check runs are ordered from most to least recent. In some cases,
+		// like when a commit is included in multiple PRs or when users re-run
+		// checks, there may be multiple runs with the same name. We only want
+		// to keep the first (most recent) result for each name.
 		for _, checkRun := range checkRuns.CheckRuns {
-			statuses[checkRun.GetName()] = checkRun.GetConclusion()
+			name := checkRun.GetName()
+			if _, exists := statuses[name]; !exists {
+				statuses[name] = checkRun.GetConclusion()
+			}
 		}
+
 		if resp.NextPage == 0 {
 			break
 		}

pull/github_test.go

@@ -644,6 +644,30 @@ func TestLatestWorkflowRuns(t *testing.T) {
 	assert.Equal(t, 2, runsRule.Count, "incorrect http request count")
 }
 
+func TestLatestStatuses(t *testing.T) {
+	pr := defaultTestPR()
+
+	rp := &ResponsePlayer{}
+	rp.AddRule(
+		ExactPathMatcher("/repos/testorg/testrepo/commits/"+pr.Head.GetSHA()+"/status"),
+		"testdata/responses/combined_status_for_ref.yml",
+	)
+	rp.AddRule(
+		ExactPathMatcher("/repos/testorg/testrepo/commits/"+pr.Head.GetSHA()+"/check-runs"),
+		"testdata/responses/check_runs_for_ref.yml",
+	)
+
+	ctx := makeContext(t, rp, pr, nil)
+	statuses, err := ctx.LatestStatuses()
+	require.NoError(t, err)
+
+	assert.Len(t, statuses, 4, "incorrect number of statuses")
+	assert.Equal(t, statuses["commit-status-a"], "success", "incorrect conclusion for 'commit-status-a' status")
+	assert.Equal(t, statuses["commit-status-b"], "pending", "incorrect conclusion for 'commit-status-a' status")
+	assert.Equal(t, statuses["check-run-a"], "success", "incorrect conclusion for 'check-run-a' status")
+	assert.Equal(t, statuses["check-run-b"], "failure", "incorrect conclusion for 'check-run-b' status")
+}
+
 func makeContext(t *testing.T, rp *ResponsePlayer, pr *github.PullRequest, gc GlobalCache) Context {
 	ctx := context.Background()
 	client := github.NewClient(&http.Client{Transport: rp})

pull/testdata/responses/check_runs_for_ref.yml

@@ -0,0 +1,28 @@
+- status: 200
+  body: |
+    {
+      "total_count": 3,
+      "check_runs": [
+        {
+          "status": "completed",
+          "conclusion": "success",
+          "started_at": "2024-08-14T12:12:45Z",
+          "completed_at": "2024-08-14T12:13:14Z",
+          "name": "check-run-a"
+        },
+        {
+          "status": "completed",
+          "conclusion": "failure",
+          "started_at": "2024-08-14T12:10:00Z",
+          "completed_at": "2024-08-14T12:10:36Z",
+          "name": "check-run-b"
+        },
+        {
+          "status": "completed",
+          "conclusion": "failure",
+          "started_at": "2024-08-14T12:10:00Z",
+          "completed_at": "2024-08-14T12:10:21Z",
+          "name": "check-run-a"
+        }
+      ]
+    }

pull/testdata/responses/combined_status_for_ref.yml

@@ -0,0 +1,19 @@
+- status: 200
+  body: |
+    {
+      "state": "pending",
+      "statuses": [
+        {
+          "state": "pending",
+          "context": "commit-status-b",
+          "created_at": "2024-08-14T12:13:14Z",
+          "updated_at": "2024-08-14T12:13:14Z"
+        },
+        {
+          "state": "success",
+          "context": "commit-status-a",
+          "created_at": "2024-08-14T12:12:00Z",
+          "updated_at": "2024-08-14T12:12:00Z"
+        }
+      ]
+    }