From db106d60855fa7536eadbe1d0a38bb65abb6511f Mon Sep 17 00:00:00 2001
From: Vincent Barbaresi <vincent.barbaresi@opendatasoft.com>
Date: Fri, 19 Oct 2018 18:59:23 +0200
Subject: [PATCH] Fix logging usage in hooks pytest_sessionstart/finish #3340

---
 changelog/3340.bugfix.rst         |  1 +
 src/_pytest/logging.py            | 23 ++++++++++++++++++++
 testing/logging/test_reporting.py | 36 +++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)
 create mode 100644 changelog/3340.bugfix.rst

diff --git a/changelog/3340.bugfix.rst b/changelog/3340.bugfix.rst
new file mode 100644
index 000000000..72b889d01
--- /dev/null
+++ b/changelog/3340.bugfix.rst
@@ -0,0 +1 @@
+Fix logging messages not shown in hooks ``pytest_sessionstart()`` and ``pytest_sessionfinish()``.
diff --git a/src/_pytest/logging.py b/src/_pytest/logging.py
index ee6795250..8244c8030 100644
--- a/src/_pytest/logging.py
+++ b/src/_pytest/logging.py
@@ -497,6 +497,29 @@ class LoggingPlugin(object):
         with self._runtest_for(None, "finish"):
             yield
 
+    @pytest.hookimpl(hookwrapper=True, tryfirst=True)
+    def pytest_sessionfinish(self):
+        with self.live_logs_context():
+            if self.log_cli_handler:
+                self.log_cli_handler.set_when("sessionfinish")
+            if self.log_file_handler is not None:
+                with catching_logs(self.log_file_handler, level=self.log_file_level):
+                    yield
+            else:
+                yield
+
+    @pytest.hookimpl(hookwrapper=True, tryfirst=True)
+    def pytest_sessionstart(self):
+        self._setup_cli_logging()
+        with self.live_logs_context():
+            if self.log_cli_handler:
+                self.log_cli_handler.set_when("sessionstart")
+            if self.log_file_handler is not None:
+                with catching_logs(self.log_file_handler, level=self.log_file_level):
+                    yield
+            else:
+                yield
+
     @pytest.hookimpl(hookwrapper=True)
     def pytest_runtestloop(self, session):
         """Runs all collected test items."""
diff --git a/testing/logging/test_reporting.py b/testing/logging/test_reporting.py
index 498b4c5bd..5863e0115 100644
--- a/testing/logging/test_reporting.py
+++ b/testing/logging/test_reporting.py
@@ -966,3 +966,39 @@ def test_collection_logging_to_file(testdir):
         assert "Normal message" in contents
         assert "debug message in test_simple" not in contents
         assert "info message in test_simple" in contents
+
+
+def test_log_in_hooks(testdir):
+    log_file = testdir.tmpdir.join("pytest.log").strpath
+
+    testdir.makeini(
+        """
+        [pytest]
+        log_file={}
+        log_file_level = INFO
+        log_cli=true
+        """.format(
+            log_file
+        )
+    )
+    testdir.makeconftest(
+        """
+        import logging
+
+        def pytest_runtestloop(session):
+            logging.info('runtestloop')
+
+        def pytest_sessionstart(session):
+            logging.info('sessionstart')
+
+        def pytest_sessionfinish(session, exitstatus):
+            logging.info('sessionfinish')
+    """
+    )
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(["*sessionstart*", "*runtestloop*", "*sessionfinish*"])
+    with open(log_file) as rfh:
+        contents = rfh.read()
+        assert "sessionstart" in contents
+        assert "runtestloop" in contents
+        assert "sessionfinish" in contents