tests: do not check the opencv command if it wasn't installed (#1431)

snaps_tests/demos_tests/test_opencv.py

@@ -25,18 +25,19 @@ class OpenCVTestCase(snaps_tests.SnapsTestCase):
     def test_opencv(self):
         snap_path = self.build_snap(self.snap_content_dir)
         self.install_snap(snap_path, 'opencv-example', '1.0')
-        output = self.run_command_in_snappy_testbed(
-            '/snap/bin/opencv-example.example').splitlines()
+        if not snaps_tests.config.get('skip-install', False):
+            output = self.run_command_in_snappy_testbed(
+                '/snap/bin/opencv-example.example').splitlines()
 
-        # Depending on opencv the result is now displayed differently
-        # so let's do a lazy match.
-        # On artful you see:
-        # [  1,   3;
-        #    2,   4]
-        # And on others:
-        # [1, 3;
-        #  2, 4]
-        expected_in_first_line = ['[', '1', ',', '3', ';']
-        self.assertThat(output[0], ContainsAll(expected_in_first_line))
-        expected_in_second_line = ['2', ',', '4', ']']
-        self.assertThat(output[1], ContainsAll(expected_in_second_line))
+            # Depending on opencv the result is now displayed differently
+            # so let's do a lazy match.
+            # On artful you see:
+            # [  1,   3;
+            #    2,   4]
+            # And on others:
+            # [1, 3;
+            #  2, 4]
+            expected_in_first_line = ['[', '1', ',', '3', ';']
+            self.assertThat(output[0], ContainsAll(expected_in_first_line))
+            expected_in_second_line = ['2', ',', '4', ']']
+            self.assertThat(output[1], ContainsAll(expected_in_second_line))