tests: Implement and register in_subprocess pytest mark

3 files changed, 118 insertions, 0 deletions

diff --git a/setup.cfg b/setup.cfg
index 06dcd8fd4..7bade2c48 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -20,6 +20,8 @@ env =
     D:XDG_CACHE_HOME=./tmp/cache
     D:XDG_CONFIG_HOME=./tmp/config
     D:XDG_DATA_HOME=./tmp/share
+markers =
+    in_subprocess: run test in a Python process forked from the main one
 
 [pycodestyle]
 max-line-length = 119
diff --git a/src/buildstream/testing/_forked.py b/src/buildstream/testing/_forked.py
new file mode 100644
index 000000000..af5e9c070
--- /dev/null
+++ b/src/buildstream/testing/_forked.py
@@ -0,0 +1,94 @@
+# This code was based on pytest-forked, commit 6098c1, found here:
+# <https://github.com/pytest-dev/pytest-forked>
+# Its copyright notice is included below.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import os
+import marshal
+
+import py
+import pytest
+# XXX Using pytest private internals here
+from _pytest import runner
+
+EXITSTATUS_TESTEXIT = 4
+
+
+# copied from xdist remote
+def serialize_report(rep):
+    d = rep.__dict__.copy()
+    if hasattr(rep.longrepr, 'toterminal'):
+        d['longrepr'] = str(rep.longrepr)
+    else:
+        d['longrepr'] = rep.longrepr
+    for name in d:
+        if isinstance(d[name], py.path.local):  # pylint: disable=no-member
+            d[name] = str(d[name])
+        elif name == "result":
+            d[name] = None  # for now
+    return d
+
+
+def forked_run_report(item):
+    def runforked():
+        try:
+            reports = runner.runtestprotocol(item, log=False)
+        except KeyboardInterrupt:
+            os._exit(EXITSTATUS_TESTEXIT)
+        return marshal.dumps([serialize_report(x) for x in reports])
+
+    ff = py.process.ForkedFunc(runforked)  # pylint: disable=no-member
+    result = ff.waitfinish()
+    if result.retval is not None:
+        report_dumps = marshal.loads(result.retval)
+        return [runner.TestReport(**x) for x in report_dumps]
+    else:
+        if result.exitstatus == EXITSTATUS_TESTEXIT:
+            pytest.exit("forked test item %s raised Exit" % (item,))
+        return [report_process_crash(item, result)]
+
+
+def report_process_crash(item, result):
+    try:
+        from _pytest.compat import getfslineno
+    except ImportError:
+        # pytest<4.2
+        path, lineno = item._getfslineno()
+    else:
+        path, lineno = getfslineno(item)
+    info = ("%s:%s: running the test CRASHED with signal %d" %
+            (path, lineno, result.signal))
+
+    # We need to create a CallInfo instance that is pre-initialised to contain
+    # info about an exception. We do this by using a function which does
+    # 0/0. Also, the API varies between pytest versions.
+    has_from_call = getattr(runner.CallInfo, "from_call", None) is not None
+    if has_from_call:  # pytest >= 4.1
+        call = runner.CallInfo.from_call(lambda: 0 / 0, "???")
+    else:
+        call = runner.CallInfo(lambda: 0 / 0, "???")
+    call.excinfo = info
+
+    rep = runner.pytest_runtest_makereport(item, call)
+    if result.out:
+        rep.sections.append(("captured stdout", result.out))
+    if result.err:
+        rep.sections.append(("captured stderr", result.err))
+    return rep
diff --git a/tests/conftest.py b/tests/conftest.py
index d6b0b02e0..7728fb5c8 100755
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -23,6 +23,7 @@ import os
 import pytest
 
 from buildstream.testing import register_repo_kind, sourcetests_collection_hook
+from buildstream.testing._forked import forked_run_report
 from buildstream.testing.integration import integration_cache  # pylint: disable=unused-import
 
 
@@ -68,6 +69,27 @@ def pytest_runtest_setup(item):
 
 
 #################################################
+#              in_subprocess mark               #
+#################################################
+#
+# Various issues can occur when forking the Python process and using gRPC,
+# due to its multithreading. As BuildStream forks for parallelisation, gRPC
+# features are restricted to child processes, so tests using them must also
+# run as child processes. The in_subprocess mark handles this.
+# See <https://github.com/grpc/grpc/blob/master/doc/fork_support.md>.
+#
+@pytest.mark.tryfirst
+def pytest_runtest_protocol(item):
+    if item.get_closest_marker('in_subprocess') is not None:
+        reports = forked_run_report(item)
+        for rep in reports:
+            item.ihook.pytest_runtest_logreport(report=rep)
+        return True
+    else:
+        return None
+
+
+#################################################
 #           remote_services fixture             #
 #################################################
 #