add --merge-json cli flag to support bktec and pants

setup.py

@@ -21,7 +21,7 @@
       zip_safe=False,
       package_dir={'': 'src'},
       packages=find_packages(where='src'),
-      install_requires=["requests>=2", "pytest>=7"],
+      install_requires=["requests>=2", "pytest>=7", "filelock>=3"],
       extras_require={
           "dev": [
               "mock>=4",

src/buildkite_test_collector/collector/payload.py

@@ -1,7 +1,7 @@
 """Buildkite Test Analytics payload"""
 
 from dataclasses import dataclass, replace, field
-from typing import Dict, Tuple, Optional, Union, Literal
+from typing import Dict, Tuple, Optional, Union, Literal, List
 from datetime import timedelta
 from uuid import UUID
 
@@ -77,7 +77,7 @@ class TestHistory:
     start_at: Optional[Instant] = None
     end_at: Optional[Instant] = None
     duration: Optional[timedelta] = None
-    children: Tuple['TestSpan'] = ()
+    children: List['TestSpan'] = ()
 
     def is_finished(self) -> bool:
         """Is there an end_at time present?"""
@@ -91,7 +91,7 @@ def as_json(self, started_at: Instant) -> JsonDict:
         """Convert this trace into a Dict for eventual serialisation into JSON"""
         attrs = {
             "section": "top",
-            "children": tuple(map(lambda span: span.as_json(started_at), self.children))
+            "children": list(map(lambda span: span.as_json(started_at), self.children))
         }
 
         if self.start_at is not None:

src/buildkite_test_collector/pytest_plugin/__init__.py

@@ -59,7 +59,7 @@ def pytest_unconfigure(config):
             # Note that when xdist is used, this JSON output file will NOT contain tags.
             jsonpath = config.option.jsonpath
             if jsonpath:
-                plugin.save_payload_as_json(jsonpath)
+                plugin.save_payload_as_json(jsonpath, merge=config.option.mergejson)
 
         del config._buildkite
         config.pluginmanager.unregister(plugin)
@@ -75,3 +75,10 @@ def pytest_addoption(parser):
         metavar="path",
         help='save json file at given path'
     )
+    group.addoption(
+        '--merge-json',
+        default=False,
+        action='store_true',
+        dest="mergejson",
+        help='merge json output with existing file, if it exists'
+    )

src/buildkite_test_collector/pytest_plugin/buildkite_plugin.py

@@ -1,7 +1,10 @@
 """Buildkite test collector plugin for Pytest"""
 import json
+import os
 from uuid import uuid4
 
+from filelock import FileLock
+
 from ..collector.payload import TestData
 from .logger import logger
 
@@ -108,7 +111,18 @@ def finalize_test(self, nodeid):
             return True
         return False
 
-    def save_payload_as_json(self, path):
-        """ Save payload into a json file """
+    def save_payload_as_json(self, path, merge=False):
+        """Save payload into a json file, merging with existing data if merge is True"""
+        data = list(self.payload.as_json()["data"])
+
+        if merge:
+            lock = FileLock(f"{path}.lock")
+            with lock:
+                if os.path.exists(path):
+                    with open(path, "r", encoding="utf-8") as f:
+                        existing_data = json.load(f)
+                    # Merge existing data with current payload
+                    data = existing_data + data
+
         with open(path, "w", encoding="utf-8") as f:
-            json.dump(self.payload.as_json()["data"], f)
+            json.dump(data, f)

tests/buildkite_test_collector/pytest_plugin/test_plugin.py

@@ -1,8 +1,9 @@
-from buildkite_test_collector.pytest_plugin import BuildkitePlugin
+import json
+import pytest
+
 from buildkite_test_collector.collector.payload import Payload
-from pathlib import Path
+from buildkite_test_collector.pytest_plugin import BuildkitePlugin
 
-import json
 
 def test_runtest_logstart_with_unstarted_payload(fake_env):
     payload = Payload.init(fake_env)
@@ -15,14 +16,101 @@ def test_runtest_logstart_with_unstarted_payload(fake_env):
     assert plugin.payload.started_at is not None
 
 
-def test_save_json_payload(fake_env, tmp_path, successful_test):
+def test_save_json_payload_without_merge(fake_env, tmp_path, successful_test):
+    payload = Payload.init(fake_env)
+    payload = Payload.started(payload)
+    payload = payload.push_test_data(successful_test)
+
+    plugin = BuildkitePlugin(payload)
+
+    path = tmp_path / "result.json"
+
+    # Create an existing file with some data
+    existing_data = [{"existing": "data"}]
+    path.write_text(json.dumps(existing_data))
+
+    # Save without merge option
+    plugin.save_payload_as_json(path, merge=False)
+
+    # Check if the data was not merged
+    expected_data = [successful_test.as_json(payload.started_at)]
+    assert json.loads(path.read_text()) == expected_data
+
+
+def test_save_json_payload_with_merge(fake_env, tmp_path, successful_test):
     payload = Payload.init(fake_env)
     payload = Payload.started(payload)
     payload = payload.push_test_data(successful_test)
 
     plugin = BuildkitePlugin(payload)
 
     path = tmp_path / "result.json"
-    plugin.save_payload_as_json(path)
 
-    assert path.read_text() == json.dumps([successful_test.as_json(payload.started_at)])
+    # Create an existing file with some data
+    existing_data = [{"existing": "data"}]
+    path.write_text(json.dumps(existing_data))
+
+    # Save with merge option
+    plugin.save_payload_as_json(path, merge=True)
+
+    # Check if the data was merged
+    expected_data = existing_data + [successful_test.as_json(payload.started_at)]
+    assert json.loads(path.read_text()) == expected_data
+
+
+def test_save_json_payload_with_non_existent_file(fake_env, tmp_path, successful_test):
+    payload = Payload.init(fake_env)
+    payload = Payload.started(payload)
+    payload = payload.push_test_data(successful_test)
+
+    plugin = BuildkitePlugin(payload)
+
+    path = tmp_path / "non_existent.json"
+
+    # Ensure the file does not exist
+    assert not path.exists()
+
+    # Save with merge option
+    plugin.save_payload_as_json(path, merge=True)
+
+    # Check if the data was saved correctly
+    expected_data = [successful_test.as_json(payload.started_at)]
+    assert json.loads(path.read_text()) == expected_data
+
+
+def test_save_json_payload_with_invalid_file(fake_env, tmp_path, successful_test):
+    payload = Payload.init(fake_env)
+    payload = Payload.started(payload)
+    payload = payload.push_test_data(successful_test)
+
+    plugin = BuildkitePlugin(payload)
+
+    path = tmp_path / "invalid.json"
+
+    # Create a file with invalid JSON
+    path.write_text("{invalid: json}")
+
+    # Save with merge option, expect JSONDecodeError
+    with pytest.raises(json.decoder.JSONDecodeError):
+        plugin.save_payload_as_json(path, merge=True)
+
+
+def test_save_json_payload_with_large_data(fake_env, tmp_path, successful_test):
+    payload = Payload.init(fake_env)
+    payload = Payload.started(payload)
+    payload = payload.push_test_data(successful_test)
+
+    plugin = BuildkitePlugin(payload)
+
+    path = tmp_path / "large_data.json"
+
+    # Create an existing file with a large amount of data
+    existing_data = [{"test": f"data_{i}"} for i in range(1000)]
+    path.write_text(json.dumps(existing_data))
+
+    # Save with merge option
+    plugin.save_payload_as_json(path, merge=True)
+
+    # Check if the data was merged correctly
+    expected_data = existing_data + [successful_test.as_json(payload.started_at)]
+    assert json.loads(path.read_text()) == expected_data