Add --cov-precision option. Close #655.

src/pytest_cov/plugin.py

@@ -149,6 +149,12 @@ def pytest_addoption(parser):
         default=None,
         help='Enable branch coverage.',
     )
+    group.addoption(
+        '--cov-precision',
+        type=int,
+        default=None,
+        help='Override the reporting precision.',
+    )
     group.addoption(
         '--cov-context',
         action='store',
@@ -257,7 +263,8 @@ class Config:
         cov_config = self.cov_controller.cov.config
         if self.options.cov_fail_under is None and hasattr(cov_config, 'fail_under'):
             self.options.cov_fail_under = cov_config.fail_under
-        self.options.cov_precision = getattr(cov_config, 'precision', 0)
+        if self.options.cov_precision is None:
+            self.options.cov_precision = getattr(cov_config, 'precision', 0)
 
     def _is_worker(self, session):
         return getattr(session.config, 'workerinput', None) is not None

tests/test_pytest_cov.py

@@ -467,6 +467,15 @@ def test_cov_min_float_value_not_reached(testdir):
     result.stdout.fnmatch_lines(['FAIL Required test coverage of 88.89% not reached. Total coverage: 88.89%'])
 
 
+def test_cov_min_float_value_not_reached_cli(testdir):
+    script = testdir.makepyfile(SCRIPT)
+    result = testdir.runpytest(
+        '-v', f'--cov={script.dirpath()}', '--cov-report=term-missing', '--cov-precision=3', '--cov-fail-under=88.89', script
+    )
+    assert result.ret == 1
+    result.stdout.fnmatch_lines(['FAIL Required test coverage of 88.89% not reached. Total coverage: 88.89%'])
+
+
 def test_cov_min_no_report(testdir):
     script = testdir.makepyfile(SCRIPT)