buildcop: handle a test suite with no tests

packages/buildcop/src/buildcop.ts

@@ -307,6 +307,10 @@ buildcop.findTestResults = (xml: string): TestResults => {
   for (const suite of testsuites) {
     const testsuiteName = suite['_attributes'].name;
     let testcases = suite['testcase'];
+    // If there were no tests in the package, continue.
+    if (testcases === undefined) {
+      continue;
+    }
     // If there is only one test case, put it into an array to make it iterable.
     if (!Array.isArray(testcases)) {
       testcases = [testcases];

packages/buildcop/test/buildcop.ts

@@ -287,6 +287,7 @@ describe('buildcop', () => {
 
         requests.done();
       });
+
       it('opens an issue [Python]', async () => {
         const input = fs.readFileSync(
           resolve(fixturesPath, 'testdata', 'python_one_failed.xml'),
@@ -358,6 +359,31 @@ describe('buildcop', () => {
         requests.done();
       });
 
+      it('handles a testsuite with no test cases', async () => {
+        const input = fs.readFileSync(
+          resolve(fixturesPath, 'testdata', 'no_tests.xml'),
+          'utf8'
+        );
+        const payload = formatPayload({
+          repo: 'tbpg/golang-samples',
+          organization: { login: 'tbpg' },
+          repository: { name: 'golang-samples' },
+          buildID: '123',
+          buildURL: 'http://example.com',
+          xunitXML: input,
+        });
+
+        const requests = nock('https://api.github.com')
+          .get(
+            '/repos/tbpg/golang-samples/issues?per_page=32&labels=buildcop%3Aissue&state=all'
+          )
+          .reply(200, []);
+
+        await probot.receive({ name: 'pubsub.message', payload, id: 'abc123' });
+
+        requests.done();
+      });
+
       it('reopens issue for failing test', async () => {
         const input = fs.readFileSync(
           resolve(fixturesPath, 'testdata', 'one_failed.xml'),

packages/buildcop/test/fixtures/testdata/no_tests.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<testsuites>
+	<testsuite tests="0" failures="0" time="266.555" name="github.com/tbpg/golang-samples/dataproc">
+		<properties>
+			<property name="go.version" value="go1.11.13"></property>
+		</properties>
+	</testsuite>
+</testsuites>