fix: Error when no simulators are available (#1470)

This should at least return a useful and actionable error message to the
end user, rather than "Cannot read property name of undefined".

Closes GH-526.
Closes GH-1366.
Closes GH-1377.
Closes GH-1469.

lib/build.js

@@ -85,10 +85,11 @@ function getDefaultSimulatorTarget () {
     events.emit('log', 'Select last emulator from list as default.');
     return require('./listEmulatorBuildTargets').run()
         .then(emulators => {
-            let targetEmulator;
-            if (emulators.length > 0) {
-                targetEmulator = emulators[0];
+            if (emulators.length === 0) {
+                return Promise.reject(new CordovaError('Could not find any iOS simulators. Use Xcode to install simulator devices for testing.'));
             }
+
+            let targetEmulator = emulators[0];
             emulators.forEach(emulator => {
                 if (emulator.name.indexOf('iPhone') === 0) {
                     targetEmulator = emulator;

tests/spec/unit/build.spec.js

@@ -418,6 +418,21 @@ describe('build', () => {
                 });
             });
         });
+
+        it('should handle the case of no simulators being available', () => {
+            // This method will require a module that supports the run method.
+            build.__set__('require', () => ({
+                run: () => Promise.resolve([])
+            }));
+
+            const getDefaultSimulatorTarget = build.__get__('getDefaultSimulatorTarget');
+
+            return getDefaultSimulatorTarget().then(sim => {
+                return Promise.reject(new Error('Should not resolve if no simulators are present'));
+            }, (err) => {
+                expect(err).toBeInstanceOf(CordovaError);
+            });
+        });
     });
 
     describe('findXCodeProjectIn method', () => {