widget.py: Avoid "showing 0 lines" messages when there are no linestlater/message-lines

This happened when bst is invoked with --message-lines 0 or
--error-lines 0, and was arguably a little too verbose (the user
explicitly asked us not to show them any lines, after all).

Fixes #779

2 files changed, 113 insertions, 2 deletions

diff --git a/buildstream/_frontend/widget.py b/buildstream/_frontend/widget.py
index a9e5eeafb..30c2e9e1a 100644
--- a/buildstream/_frontend/widget.py
+++ b/buildstream/_frontend/widget.py
@@ -647,8 +647,9 @@ class LogLine(Widget):
             abbrev = False
             if message.message_type not in ERROR_MESSAGES \
                and not frontend_message and n_lines > self._message_lines:
-                abbrev = True
                 lines = lines[0:self._message_lines]
+                if self._message_lines > 0:
+                    abbrev = True
             else:
                 lines[n_lines - 1] = lines[n_lines - 1].rstrip('\n')
 
@@ -674,7 +675,7 @@ class LogLine(Widget):
             if self.context is not None and not self.context.log_verbose:
                 text += self._indent + self._err_profile.fmt("Log file: ")
                 text += self._indent + self._logfile_widget.render(message) + '\n'
-            else:
+            elif self._log_lines > 0:
                 text += self._indent + self._err_profile.fmt("Printing the last {} lines from log file:"
                                                              .format(self._log_lines)) + '\n'
                 text += self._indent + self._logfile_widget.render(message, abbrev=False) + '\n'
diff --git a/tests/integration/messages.py b/tests/integration/messages.py
new file mode 100644
index 000000000..775921cba
--- /dev/null
+++ b/tests/integration/messages.py
@@ -0,0 +1,110 @@
+#
+#  Copyright (C) 2018 Codethink Limited
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU Lesser General Public
+#  License as published by the Free Software Foundation; either
+#  version 2 of the License, or (at your option) any later version.
+#
+#  This library is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#  Lesser General Public License for more details.
+#
+#  You should have received a copy of the GNU Lesser General Public
+#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
+#
+#  Authors: Tristan Maat <tristan.maat@codethink.co.uk>
+#
+
+import os
+import pytest
+
+from buildstream import _yaml
+from buildstream._exceptions import ErrorDomain
+
+from tests.testutils import cli_integration as cli
+from tests.testutils.site import HAVE_BWRAP, IS_LINUX
+
+
+pytestmark = pytest.mark.integration
+
+
+# Project directory
+DATA_DIR = os.path.join(
+    os.path.dirname(os.path.realpath(__file__)),
+    "project",
+)
+
+
+@pytest.mark.integration
+@pytest.mark.datafiles(DATA_DIR)
+@pytest.mark.skipif(IS_LINUX and not HAVE_BWRAP, reason='Only available with bubblewrap on Linux')
+def test_disable_message_lines(cli, tmpdir, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    element_path = os.path.join(project, 'elements')
+    element_name = 'message.bst'
+
+    element = {
+        'kind': 'manual',
+        'depends': [{
+            'filename': 'base.bst'
+        }],
+        'config': {
+            'build-commands':
+            ['echo "Silly message"'],
+            'strip-commands': []
+        }
+    }
+
+    os.makedirs(os.path.dirname(os.path.join(element_path, element_name)), exist_ok=True)
+    _yaml.dump(element, os.path.join(element_path, element_name))
+
+    # First we check that we get the "Silly message"
+    result = cli.run(project=project, args=["build", element_name])
+    result.assert_success()
+    assert 'echo "Silly message"' in result.stderr
+
+    # Let's now build it again, but with --message-lines 0
+    cli.remove_artifact_from_cache(project, element_name)
+    result = cli.run(project=project, args=["--message-lines", "0",
+                                            "build", element_name])
+    result.assert_success()
+    assert "Message contains " not in result.stderr
+
+
+@pytest.mark.integration
+@pytest.mark.datafiles(DATA_DIR)
+@pytest.mark.skipif(IS_LINUX and not HAVE_BWRAP, reason='Only available with bubblewrap on Linux')
+def test_disable_error_lines(cli, tmpdir, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    element_path = os.path.join(project, 'elements')
+    element_name = 'message.bst'
+
+    element = {
+        'kind': 'manual',
+        'depends': [{
+            'filename': 'base.bst'
+        }],
+        'config': {
+            'build-commands':
+            ['This is a syntax error > >'],
+            'strip-commands': []
+        }
+    }
+
+    os.makedirs(os.path.dirname(os.path.join(element_path, element_name)), exist_ok=True)
+    _yaml.dump(element, os.path.join(element_path, element_name))
+
+    # First we check that we get the syntax error
+    result = cli.run(project=project, args=["--error-lines", "0",
+                                            "build", element_name])
+    result.assert_main_error(ErrorDomain.STREAM, None)
+    assert "This is a syntax error" in result.stderr
+
+    # Let's now build it again, but with --error-lines 0
+    cli.remove_artifact_from_cache(project, element_name)
+    result = cli.run(project=project, args=["--error-lines", "0",
+                                            "build", element_name])
+    result.assert_main_error(ErrorDomain.STREAM, None)
+    assert "Printing the last" not in result.stderr