Merge pull request pytest-dev#3585 from wcooley/feature/3579-caplog-m…

…essages

Add `messages` property to `caplog` fixture.

AUTHORS

@@ -204,6 +204,7 @@ Victor Uriarte
 Vidar T. Fauske
 Vitaly Lashmanov
 Vlad Dragos
+Wil Cooley
 William Lee
 Wouter van Ackooy
 Xuan Luong

changelog/3579.feature.rst

@@ -0,0 +1 @@
+Fixture ``caplog`` now has a ``messages`` property, providing convenient access to the format-interpolated log messages without the extra data provided by the formatter/handler.

src/_pytest/logging.py

@@ -270,6 +270,22 @@ def record_tuples(self):
         """
         return [(r.name, r.levelno, r.getMessage()) for r in self.records]
 
+    @property
+    def messages(self):
+        """Returns a list of format-interpolated log messages.
+
+        Unlike 'records', which contains the format string and parameters for interpolation, log messages in this list
+        are all interpolated.
+        Unlike 'text', which contains the output from the handler, log messages in this list are unadorned with
+        levels, timestamps, etc, making exact comparisions more reliable.
+
+        Note that traceback or stack info (from :func:`logging.exception` or the `exc_info` or `stack_info` arguments
+        to the logging functions) is not included, as this is added by the formatter in the handler.
+
+        .. versionadded:: 3.7
+        """
+        return [r.getMessage() for r in self.records]
+
     def clear(self):
         """Reset the list of log records and the captured log text."""
         self.handler.reset()

testing/logging/test_fixture.py

@@ -73,6 +73,27 @@ def test_log_access(caplog):
     assert "boo arg" in caplog.text
 
 
+def test_messages(caplog):
+    caplog.set_level(logging.INFO)
+    logger.info("boo %s", "arg")
+    logger.info("bar %s\nbaz %s", "arg1", "arg2")
+    assert "boo arg" == caplog.messages[0]
+    assert "bar arg1\nbaz arg2" == caplog.messages[1]
+    assert caplog.text.count("\n") > len(caplog.messages)
+    assert len(caplog.text.splitlines()) > len(caplog.messages)
+
+    try:
+        raise Exception("test")
+    except Exception:
+        logger.exception("oops")
+
+    assert "oops" in caplog.text
+    assert "oops" in caplog.messages[-1]
+    # Tracebacks are stored in the record and not added until the formatter or handler.
+    assert "Exception" in caplog.text
+    assert "Exception" not in caplog.messages[-1]
+
+
 def test_record_tuples(caplog):
     caplog.set_level(logging.INFO)
     logger.info("boo %s", "arg")