[ci][microcheck] manually add tests to microcheck (#45400)

Allow PR owners to add tests to microcheck manually by adding a line
with syntax

`@microcheck //test_target_01 //test_target_02`

to the git commit message. Thanks @stephanie-wang for the great idea.

Note that it's ok to provide an invalid target because `tester` will
re-validate them with `bazel query`.

Test:
- //release:test_config is manually added and run
https://buildkite.com/ray-project/microcheck/builds/169#018f84d5-1024-4285-a3fa-59a96e925563/179-1057

---------

Signed-off-by: can <can@anyscale.com>

ci/ray_ci/test_tester.py

@@ -18,6 +18,7 @@
     _get_tag_matcher,
     _get_changed_files,
     _get_changed_tests,
+    _get_human_specified_tests,
 )
 from ray_release.test import Test, TestState
 
@@ -214,6 +215,7 @@ def test_get_high_impact_test_targets() -> None:
         {
             "input": [],
             "new_tests": set(),
+            "human_tests": set(),
             "output": set(),
         },
         {
@@ -232,9 +234,11 @@ def test_get_high_impact_test_targets() -> None:
                 ),
             ],
             "new_tests": {"//core_new"},
+            "human_tests": {"//human_test"},
             "output": {
                 "//core_good",
                 "//core_new",
+                "//human_test",
             },
         },
     ]
@@ -245,6 +249,9 @@ def test_get_high_impact_test_targets() -> None:
         ), mock.patch(
             "ci.ray_ci.tester._get_changed_tests",
             return_value=test["new_tests"],
+        ), mock.patch(
+            "ci.ray_ci.tester._get_human_specified_tests",
+            return_value=test["human_tests"],
         ):
             assert (
                 _get_high_impact_test_targets(
@@ -256,7 +263,10 @@ def test_get_high_impact_test_targets() -> None:
             )
 
 
-@mock.patch.dict(os.environ, {"BUILDKITE_PULL_REQUEST_BASE_BRANCH": "base"})
+@mock.patch.dict(
+    os.environ,
+    {"BUILDKITE_PULL_REQUEST_BASE_BRANCH": "base", "BUILDKITE_COMMIT": "commit"},
+)
 @mock.patch("subprocess.check_call")
 @mock.patch("subprocess.check_output")
 def test_get_changed_files(mock_check_output, mock_check_call) -> None:
@@ -277,6 +287,17 @@ def test_get_changed_tests(
     assert _get_changed_tests() == {"//t1", "//t2"}
 
 
+@mock.patch.dict(
+    os.environ,
+    {"BUILDKITE_PULL_REQUEST_BASE_BRANCH": "base", "BUILDKITE_COMMIT": "commit"},
+)
+@mock.patch("subprocess.check_call")
+@mock.patch("subprocess.check_output")
+def test_get_human_specified_tests(mock_check_output, mock_check_call) -> None:
+    mock_check_output.return_value = b"hi\n@microcheck //test01 //test02\nthere"
+    assert _get_human_specified_tests() == {"//test01", "//test02"}
+
+
 def test_get_flaky_test_targets() -> None:
     test_harness = [
         {

ci/ray_ci/tester.py

@@ -38,6 +38,7 @@
 """  # noqa: E501
 
 DEFAULT_EXCEPT_TAGS = {"manual"}
+MICROCHECK_COMMAND = "@microcheck"
 
 # Gets the path of product/tools/docker (i.e. the parent of 'common')
 bazel_workspace_dir = os.environ.get("BUILD_WORKSPACE_DIRECTORY", "")
@@ -416,8 +417,32 @@ def _get_high_impact_test_targets(
         if test.get_oncall() == team
     }
     changed_tests = _get_changed_tests()
+    human_specified_tests = _get_human_specified_tests()
 
-    return high_impact_tests.union(changed_tests)
+    return high_impact_tests.union(changed_tests).union(human_specified_tests)
+
+
+def _get_human_specified_tests() -> Set[str]:
+    """
+    Get all test targets that are specified by humans
+    """
+    base = os.environ.get("BUILDKITE_PULL_REQUEST_BASE_BRANCH")
+    head = os.environ.get("BUILDKITE_COMMIT")
+    if not base or not head:
+        # if not in a PR, return an empty set
+        return set()
+
+    tests = set()
+    messages = subprocess.check_output(
+        ["git", "rev-list", "--format=%b", f"origin/{base}...{head}"],
+        cwd=bazel_workspace_dir,
+    )
+    for message in messages.decode().splitlines():
+        if message.startswith(MICROCHECK_COMMAND):
+            tests = tests.union(message[len(MICROCHECK_COMMAND) :].strip().split(" "))
+    logger.info(f"Human specified tests: {tests}")
+
+    return tests
 
 
 def _get_changed_tests() -> Set[str]:
@@ -472,7 +497,6 @@ def _get_changed_files() -> Set[str]:
         # if not in a PR, return an empty set
         return set()
 
-    subprocess.check_call(["git", "fetch", "origin", base], cwd=bazel_workspace_dir)
     changes = subprocess.check_output(
         ["git", "diff", "--name-only", f"origin/{base}...{head}"],
         cwd=bazel_workspace_dir,