tests/fprintd: Verify that each enroll stage happens

Instead of automatically replying with the 'whorl' image for every enroll
state signal with result 'enroll-stage-passed', only perform the number
of required enroll stages and ensure that we get the expected results.

This also will allow to manually perform enroll steps in other tests.

tests/fprintd.py

@@ -307,8 +307,9 @@ class FPrintdVirtualDeviceTest(FPrintdTest):
                 self._abort = params[1]
                 self._last_result = params[0]
 
-                if not self._abort and self._last_result == 'enroll-stage-passed':
-                    self.send_image('whorl')
+                if not self._abort and self._last_result.startswith('enroll-'):
+                    # Exit wait loop, onto next enroll state (if any)
+                    self._abort = True
                 elif self._abort:
                     pass
                 else:
@@ -354,8 +355,13 @@ class FPrintdVirtualDeviceTest(FPrintdTest):
     def enroll_image(self, img, finger='right-index-finger'):
         self.device.EnrollStart('(s)', finger)
 
-        self.send_image(img)
-        self.wait_for_result()
+        stages = self.device.get_cached_property('num-enroll-stages').unpack()
+        for stage in range(stages):
+            self.send_image(img)
+            if stage < stages - 1:
+                self.wait_for_result('enroll-stage-passed')
+            else:
+                self.wait_for_result('enroll-completed')
 
         self.device.EnrollStop()
         self.assertEqual(self._last_result, 'enroll-completed')