Add support for LCOV output

Coverage.py 6.3 gained support for the LCOV output format. Add support
for this to pytest-cov via '--cov-report=lcov[:dest]'.

Fix: #535

Author: fetzerch

Diff for: AUTHORS.rst

@@ -51,3 +51,4 @@ Authors
 * Danilo Šegan - https://github.com/dsegan
 * Michał Bielawski - https://github.com/D3X
 * Zac Hatfield-Dodds - https://github.com/Zac-HD
+* Christian Fetzer - https://github.com/fetzerch

Diff for: CHANGELOG.rst

@@ -21,6 +21,9 @@ Changelog
     concurrency = multiprocessing
     parallel = true
     sigterm = true
+* Added support for LCOV output format via `--cov-report=lcov`. Only works with coverage 6.3+.
+  Contributed by Christian Fetzer in
+  `#536 <https://github.com/pytest-dev/pytest-cov/issues/536>`_.
 
 * Use modern way to specify hook options to avoid deprecation warnings with pytest >=7.2.
 

Diff for: docs/config.rst

@@ -56,9 +56,9 @@ The complete list of command line options is:
 
   --cov=PATH            Measure coverage for filesystem path. (multi-allowed)
   --cov-report=type     Type of report to generate: term, term-missing,
-                        annotate, html, xml (multi-allowed). term, term-
+                        annotate, html, xml, lcov (multi-allowed). term, term-
                         missing may be followed by ":skip-covered". annotate,
-                        html and xml may be followed by ":DEST" where DEST
+                        html, xml and lcov may be followed by ":DEST" where DEST
                         specifies the output location. Use --cov-report= to
                         not generate any output.
   --cov-config=path     Config file for coverage. Default: .coveragerc

Diff for: docs/reporting.rst

@@ -3,7 +3,7 @@ Reporting
 
 It is possible to generate any combination of the reports for a single test run.
 
-The available reports are terminal (with or without missing line numbers shown), HTML, XML and
+The available reports are terminal (with or without missing line numbers shown), HTML, XML, LCOV and
 annotated source code.
 
 The terminal report without line numbers (default)::
@@ -49,19 +49,21 @@ The terminal report with skip covered::
 
 You can use ``skip-covered`` with ``term-missing`` as well. e.g. ``--cov-report term-missing:skip-covered``
 
-These three report options output to files without showing anything on the terminal::
+These four report options output to files without showing anything on the terminal::
 
     pytest --cov-report html
             --cov-report xml
+            --cov-report lcov
             --cov-report annotate
             --cov=myproj tests/
 
-The output location for each of these reports can be specified. The output location for the XML
+The output location for each of these reports can be specified. The output location for the XML and LCOV
 report is a file. Where as the output location for the HTML and annotated source code reports are
 directories::
 
     pytest --cov-report html:cov_html
             --cov-report xml:cov.xml
+            --cov-report lcov:cov.info
             --cov-report annotate:cov_annotate
             --cov=myproj tests/
 

Diff for: src/pytest_cov/engine.py

@@ -196,6 +196,18 @@ def summary(self, stream):
                 total = self.cov.xml_report(ignore_errors=True, outfile=output)
             stream.write('Coverage XML written to file %s\n' % (self.cov.config.xml_output if output is None else output))
 
+        # Produce lcov report if wanted.
+        if 'lcov' in self.cov_report:
+            output = self.cov_report['lcov']
+            with _backup(self.cov, "config"):
+                self.cov.lcov_report(ignore_errors=True, outfile=output)
+
+                # We need to call Coverage.report here, just to get the total
+                # Coverage.lcov_report doesn't return any total and we need it for --cov-fail-under.
+                total = self.cov.report(ignore_errors=True, file=_NullFile)
+
+            stream.write('Coverage LCOV written to file %s\n' % (self.cov.config.lcov_output if output is None else output))
+
         return total
 
 

Diff for: src/pytest_cov/plugin.py

@@ -29,7 +29,7 @@ class CovReportWarning(PytestCovWarning):
 
 
 def validate_report(arg):
-    file_choices = ['annotate', 'html', 'xml']
+    file_choices = ['annotate', 'html', 'xml', 'lcov']
     term_choices = ['term', 'term-missing']
     term_modifier_choices = ['skip-covered']
     all_choices = term_choices + file_choices
@@ -39,6 +39,9 @@ def validate_report(arg):
         msg = f'invalid choice: "{arg}" (choose from "{all_choices}")'
         raise argparse.ArgumentTypeError(msg)
 
+    if report_type == 'lcov' and coverage.version_info <= (6, 3):
+        raise argparse.ArgumentTypeError('LCOV output is only supported with coverage.py >= 6.3')
+
     if len(values) == 1:
         return report_type, None
 
@@ -96,9 +99,9 @@ def pytest_addoption(parser):
     group.addoption('--cov-report', action=StoreReport, default={},
                     metavar='TYPE', type=validate_report,
                     help='Type of report to generate: term, term-missing, '
-                         'annotate, html, xml (multi-allowed). '
+                         'annotate, html, xml, lcov (multi-allowed). '
                          'term, term-missing may be followed by ":skip-covered". '
-                         'annotate, html and xml may be followed by ":DEST" '
+                         'annotate, html, xml and lcov may be followed by ":DEST" '
                          'where DEST specifies the output location. '
                          'Use --cov-report= to not generate any output.')
     group.addoption('--cov-config', action='store', default='.coveragerc',

Diff for: tests/test_pytest_cov.py

@@ -150,7 +150,8 @@ def test_foo(cov):
 CHILD_SCRIPT_RESULT = '[56] * 100%'
 PARENT_SCRIPT_RESULT = '9 * 100%'
 DEST_DIR = 'cov_dest'
-REPORT_NAME = 'cov.xml'
+XML_REPORT_NAME = 'cov.xml'
+LCOV_REPORT_NAME = 'cov.info'
 
 xdist_params = pytest.mark.parametrize('opts', [
     '',
@@ -333,18 +334,50 @@ def test_xml_output_dir(testdir):
 
     result = testdir.runpytest('-v',
                                '--cov=%s' % script.dirpath(),
-                               '--cov-report=xml:' + REPORT_NAME,
+                               '--cov-report=xml:' + XML_REPORT_NAME,
                                script)
 
     result.stdout.fnmatch_lines([
         '*- coverage: platform *, python * -*',
-        'Coverage XML written to file ' + REPORT_NAME,
+        'Coverage XML written to file ' + XML_REPORT_NAME,
         '*10 passed*',
     ])
-    assert testdir.tmpdir.join(REPORT_NAME).check()
+    assert testdir.tmpdir.join(XML_REPORT_NAME).check()
     assert result.ret == 0
 
 
+@pytest.mark.skipif("coverage.version_info < (6, 3)")
+def test_lcov_output_dir(testdir):
+    script = testdir.makepyfile(SCRIPT)
+
+    result = testdir.runpytest('-v',
+                               '--cov=%s' % script.dirpath(),
+                               '--cov-report=lcov:' + LCOV_REPORT_NAME,
+                               script)
+
+    result.stdout.fnmatch_lines([
+        '*- coverage: platform *, python * -*',
+        'Coverage LCOV written to file ' + LCOV_REPORT_NAME,
+        '*10 passed*',
+    ])
+    assert testdir.tmpdir.join(LCOV_REPORT_NAME).check()
+    assert result.ret == 0
+
+
+@pytest.mark.skipif("coverage.version_info >= (6, 3)")
+def test_lcov_not_supported(testdir):
+    script = testdir.makepyfile("a = 1")
+    result = testdir.runpytest('-v',
+                               '--cov=%s' % script.dirpath(),
+                               '--cov-report=lcov',
+                               script,
+                               )
+    result.stderr.fnmatch_lines([
+        '*argument --cov-report: LCOV output is only supported with coverage.py >= 6.3',
+    ])
+    assert result.ret != 0
+
+
 def test_term_output_dir(testdir):
     script = testdir.makepyfile(SCRIPT)