diff --git a/api/pull_request_test.go b/api/pull_request_test.go
index 2e4fa73b1..67ea20cb5 100644
--- a/api/pull_request_test.go
+++ b/api/pull_request_test.go
@@ -2,42 +2,295 @@ package api
 
 import (
 	"encoding/json"
+	"fmt"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
-func TestPullRequest_ChecksStatus(t *testing.T) {
-	pr := PullRequest{}
+func TestChecksStatus_NoCheckRunsOrStatusContexts(t *testing.T) {
+	t.Parallel()
+
 	payload := `
+	{ "statusCheckRollup": { "nodes": [] } }
+	`
+	var pr PullRequest
+	require.NoError(t, json.Unmarshal([]byte(payload), &pr))
+
+	expectedChecksStatus := PullRequestChecksStatus{
+		Pending: 0,
+		Failing: 0,
+		Passing: 0,
+		Total:   0,
+	}
+	require.Equal(t, expectedChecksStatus, pr.ChecksStatus())
+}
+
+func TestChecksStatus_SummarisingCheckRuns(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                 string
+		payload              string
+		expectedChecksStatus PullRequestChecksStatus
+	}{
+		{
+			name:                 "QUEUED is treated as Pending",
+			payload:              singleCheckRunWithStatus("QUEUED"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "IN_PROGRESS is treated as Pending",
+			payload:              singleCheckRunWithStatus("IN_PROGRESS"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "WAITING is treated as Pending",
+			payload:              singleCheckRunWithStatus("WAITING"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "PENDING is treated as Pending",
+			payload:              singleCheckRunWithStatus("PENDING"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "REQUESTED is treated as Pending",
+			payload:              singleCheckRunWithStatus("REQUESTED"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / STARTUP_FAILURE is treated as Pending",
+			payload:              singleCompletedCheckRunWithConclusion("STARTUP_FAILURE"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / STALE is treated as Pending",
+			payload:              singleCompletedCheckRunWithConclusion("STALE"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / SUCCESS is treated as Passing",
+			payload:              singleCompletedCheckRunWithConclusion("SUCCESS"),
+			expectedChecksStatus: PullRequestChecksStatus{Passing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / NEUTRAL is treated as Passing",
+			payload:              singleCompletedCheckRunWithConclusion("NEUTRAL"),
+			expectedChecksStatus: PullRequestChecksStatus{Passing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / SKIPPED is treated as Passing",
+			payload:              singleCompletedCheckRunWithConclusion("SKIPPED"),
+			expectedChecksStatus: PullRequestChecksStatus{Passing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / ACTION_REQUIRED is treated as Failing",
+			payload:              singleCompletedCheckRunWithConclusion("ACTION_REQUIRED"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / TIMED_OUT is treated as Failing",
+			payload:              singleCompletedCheckRunWithConclusion("TIMED_OUT"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / CANCELLED is treated as Failing",
+			payload:              singleCompletedCheckRunWithConclusion("CANCELLED"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / CANCELLED is treated as Failing",
+			payload:              singleCompletedCheckRunWithConclusion("CANCELLED"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "COMPLETED / FAILURE is treated as Failing",
+			payload:              singleCompletedCheckRunWithConclusion("FAILURE"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "Unrecognized Status are treated as Pending",
+			payload:              singleCheckRunWithStatus("AnUnrecognizedStatusJustForThisTest"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "Unrecognized Conclusions are treated as Pending",
+			payload:              singleCompletedCheckRunWithConclusion("AnUnrecognizedConclusionJustForThisTest"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			var pr PullRequest
+			require.NoError(t, json.Unmarshal([]byte(tt.payload), &pr))
+
+			require.Equal(t, tt.expectedChecksStatus, pr.ChecksStatus())
+		})
+	}
+}
+
+func TestChecksStatus_SummarisingStatusContexts(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                 string
+		payload              string
+		expectedChecksStatus PullRequestChecksStatus
+	}{
+		{
+			name:                 "EXPECTED is treated as Pending",
+			payload:              singleStatusContextWithState("EXPECTED"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "PENDING is treated as Pending",
+			payload:              singleStatusContextWithState("PENDING"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+		{
+			name:                 "SUCCESS is treated as Passing",
+			payload:              singleStatusContextWithState("SUCCESS"),
+			expectedChecksStatus: PullRequestChecksStatus{Passing: 1, Total: 1},
+		},
+		{
+			name:                 "ERROR is treated as Failing",
+			payload:              singleStatusContextWithState("ERROR"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "FAILURE is treated as Failing",
+			payload:              singleStatusContextWithState("FAILURE"),
+			expectedChecksStatus: PullRequestChecksStatus{Failing: 1, Total: 1},
+		},
+		{
+			name:                 "Unrecognized States are treated as Pending",
+			payload:              singleStatusContextWithState("AnUnrecognizedStateJustForThisTest"),
+			expectedChecksStatus: PullRequestChecksStatus{Pending: 1, Total: 1},
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			var pr PullRequest
+			require.NoError(t, json.Unmarshal([]byte(tt.payload), &pr))
+
+			require.Equal(t, tt.expectedChecksStatus, pr.ChecksStatus())
+		})
+	}
+}
+
+func TestChecksStatus_SummarisingCheckRunsAndStatusContexts(t *testing.T) {
+	t.Parallel()
+
+	// This might look a bit intimidating, but we're just inserting three nodes
+	// into the rollup, two completed check run nodes and one status context node.
+	payload := fmt.Sprintf(`
 	{ "statusCheckRollup": { "nodes": [{ "commit": {
 		"statusCheckRollup": {
 			"contexts": {
 				"nodes": [
-					{ "state": "SUCCESS" },
-					{ "state": "PENDING" },
-					{ "state": "FAILURE" },
-					{ "status": "IN_PROGRESS",
-					  "conclusion": null },
-					{ "status": "COMPLETED",
-					  "conclusion": "SUCCESS" },
-					{ "status": "COMPLETED",
-					  "conclusion": "FAILURE" },
-					{ "status": "COMPLETED",
-					  "conclusion": "ACTION_REQUIRED" },
-					{ "status": "COMPLETED",
-					  "conclusion": "STALE" }
+					%s,
+					%s,
+					%s
 				]
 			}
 		}
 	} }] } }
-	`
-	err := json.Unmarshal([]byte(payload), &pr)
-	assert.NoError(t, err)
+	`,
+		completedCheckRunNode("SUCCESS"),
+		statusContextNode("PENDING"),
+		completedCheckRunNode("FAILURE"),
+	)
 
-	checks := pr.ChecksStatus()
-	assert.Equal(t, 8, checks.Total)
-	assert.Equal(t, 3, checks.Pending)
-	assert.Equal(t, 3, checks.Failing)
-	assert.Equal(t, 2, checks.Passing)
+	var pr PullRequest
+	require.NoError(t, json.Unmarshal([]byte(payload), &pr))
+
+	expectedChecksStatus := PullRequestChecksStatus{
+		Pending: 1,
+		Failing: 1,
+		Passing: 1,
+		Total:   3,
+	}
+	require.Equal(t, expectedChecksStatus, pr.ChecksStatus())
+}
+
+// Note that it would be incorrect to provide a status of COMPLETED here
+// as the conclusion is always set to null. If you want a COMPLETED status,
+// use `singleCompletedCheckRunWithConclusion`.
+func singleCheckRunWithStatus(status string) string {
+	return fmt.Sprintf(`
+	{ "statusCheckRollup": { "nodes": [{ "commit": {
+		"statusCheckRollup": {
+			"contexts": {
+				"nodes": [
+					{
+						"__typename": "CheckRun",
+						"status": "%s",
+						"conclusion": null
+					}
+				]
+			}
+		}
+	} }] } }
+	`, status)
+}
+
+func singleCompletedCheckRunWithConclusion(conclusion string) string {
+	return fmt.Sprintf(`
+	{ "statusCheckRollup": { "nodes": [{ "commit": {
+		"statusCheckRollup": {
+			"contexts": {
+				"nodes": [
+					{
+						"__typename": "CheckRun",
+						"status": "COMPLETED",
+						"conclusion": "%s"
+					}
+				]
+			}
+		}
+	} }] } }
+	`, conclusion)
+}
+
+func singleStatusContextWithState(state string) string {
+	return fmt.Sprintf(`
+	{ "statusCheckRollup": { "nodes": [{ "commit": {
+		"statusCheckRollup": {
+			"contexts": {
+				"nodes": [
+					{
+						"__typename": "StatusContext",
+						"state": "%s"
+					}
+				]
+			}
+		}
+	} }] } }
+	`, state)
+}
+
+func completedCheckRunNode(conclusion string) string {
+	return fmt.Sprintf(`
+	{
+		"__typename": "CheckRun",
+		"status": "COMPLETED",
+		"conclusion": "%s"
+	}`, conclusion)
+}
+
+func statusContextNode(state string) string {
+	return fmt.Sprintf(`
+	{
+		"__typename": "StatusContext",
+		"state": "%s"
+	}`, state)
 }