Added a test

Author: kohsuke

tests/data/karma/subset_result.json

@@ -0,0 +1,22 @@
+{
+  "testPaths": [
+    [
+      {
+        "type": "file",
+        "name": "a.ts"
+      }
+    ],
+    [
+      {
+        "type": "file",
+        "name": "b.ts"
+      }
+    ]
+  ],
+  "testRunner": "karma",
+  "session": { "id": "16" },
+  "goal": {"type": "subset-by-percentage", "percentage": 0.1},
+  "ignoreNewTests": false,
+  "getTestsFromGuess": false,
+  "getTestsFromPreviousSessions": false
+}

tests/test_runners/test_karma.py

@@ -3,6 +3,7 @@
 
 import responses  # type: ignore
 
+from launchable.utils.session import write_build
 from tests.cli_test_case import CliTestCase
 
 
@@ -16,3 +17,14 @@ def test_record_tests_json(self):
 
         self.assert_success(result)
         self.assert_record_tests_payload('record_test_result.json')
+
+    @responses.activate
+    @mock.patch.dict(os.environ, {"LAUNCHABLE_TOKEN": CliTestCase.launchable_token})
+    def test_subset(self):
+        # emulate launchable record build
+        write_build(self.build_name)
+
+        result = self.cli('subset', '--target', '10%', '--base',
+                          os.getcwd(), 'karma', '--with', 'ng', input="a.ts\nb.ts")
+        self.assert_success(result)
+        self.assert_subset_payload('subset_result.json')