Fix an issue where removing a subscription would throw an undefined error (#12)

Author: simenbrekken

src/connect.js

@@ -27,7 +27,7 @@ export default (mapFirebaseToProps = defaultMapFirebaseToProps) => {
 
   const computeSubscriptions = (props, ref, firebaseApp) => {
     const firebaseProps = mapFirebase(props, ref, firebaseApp)
-    const subscriptions = pickBy(firebaseProps, prop => isString(prop) || prop.path)
+    const subscriptions = pickBy(firebaseProps, prop => isString(prop) || (prop && prop.path))
 
     invariant(
       isPlainObject(subscriptions),

src/tests/connect-test.js

@@ -185,4 +185,25 @@ test('Should pass props, ref and firebase to mapFirebaseToProps', assert => {
   assert.end()
 })
 
-test('Should update subscriptions when props change')
+test('Should update subscriptions when props change', assert => {
+  const mapFirebaseToProps = props => ({ foo: props.foo, bar: props.bar })
+
+  const firebaseApp = createMockApp()
+  const initial = renderStub(mapFirebaseToProps, firebaseApp, { foo: 'foo' })
+  assert.equal(initial.props.foo, 'foo value')
+  assert.equal(initial.props.bar, undefined)
+
+  const added = renderStub(mapFirebaseToProps, firebaseApp, { foo: 'foo', bar: 'bar' })
+  assert.equal(added.props.foo, 'foo value')
+  assert.equal(added.props.bar, 'bar value')
+
+  const changed = renderStub(mapFirebaseToProps, firebaseApp, { foo: 'foo', bar: 'baz' })
+  assert.equal(changed.props.foo, 'foo value')
+  assert.equal(changed.props.bar, 'baz value')
+
+  const removed = renderStub(mapFirebaseToProps, firebaseApp, { bar: 'baz' })
+  assert.equal(removed.props.foo, undefined)
+  assert.equal(removed.props.bar, 'baz value')
+
+  assert.end()
+})