Add --overwrite-ini ININAME=INIVALUE cli option

AUTHORS

@@ -100,6 +100,7 @@ Samuele Pedroni
 Steffen Allner
 Stephan Obermann
 Tareq Alayan
+Ted Xiao
 Simon Gomizelj
 Stefano Taschini
 Stefan Farmbauer

CHANGELOG.rst

@@ -79,6 +79,10 @@
   finalizer and has access to the fixture's result cache.
   Thanks `@d6e`_, `@sallner`_
 
+* New cli flag ``--override-ini`` or ``-o`` that overrides values from the ini file.
+  Example '-o xfail_strict=True'. A complete ini-options can be viewed
+  by py.test --help. Thanks `@blueyed`_ and `@fengxx`_ for the PR
+
 
 **Changes**
 
@@ -155,6 +159,8 @@
 .. _@nikratio: https://github.com/nikratio
 .. _@RedBeardCode: https://github.com/RedBeardCode
 .. _@Vogtinator: https://github.com/Vogtinator
+.. _@blueyed: https://github.com/blueyed
+.. _@fengxx: https://github.com/fengxx
 
 * Fix `#1421`_: Exit tests if a collection error occurs and add
   ``--continue-on-collection-errors`` option to restore previous behaviour.

_pytest/config.py

@@ -1003,14 +1003,16 @@ def _getini(self, name):
             description, type, default = self._parser._inidict[name]
         except KeyError:
             raise ValueError("unknown configuration value: %r" %(name,))
-        try:
-            value = self.inicfg[name]
-        except KeyError:
-            if default is not None:
-                return default
-            if type is None:
-                return ''
-            return []
+        value = self._get_override_ini_value(name)
+        if value is None:
+            try:
+                value = self.inicfg[name]
+            except KeyError:
+                if default is not None:
+                    return default
+                if type is None:
+                    return ''
+                return []
         if type == "pathlist":
             dp = py.path.local(self.inicfg.config.path).dirpath()
             l = []
@@ -1041,6 +1043,20 @@ def _getconftest_pathlist(self, name, path):
             l.append(relroot)
         return l
 
+    def _get_override_ini_value(self, name):
+        value = None
+        # override_ini is a list of list, to support both -o foo1=bar1 foo2=bar2 and
+        # and -o foo1=bar1 -o foo2=bar2 options
+        # always use the last item if multiple value set for same ini-name,
+        # e.g. -o foo=bar1 -o foo=bar2 will set foo to bar2
+        if self.getoption("override_ini", None):
+            for ini_config_list in self.option.override_ini:
+                for ini_config in ini_config_list:
+                    (key, user_ini_value) = ini_config.split("=", 1)
+                    if key == name:
+                        value = user_ini_value
+        return value
+
     def getoption(self, name, default=notset, skip=False):
         """ return command line option value.
 

_pytest/helpconfig.py

@@ -20,6 +20,10 @@ def pytest_addoption(parser):
     group.addoption('--debug',
                action="store_true", dest="debug", default=False,
                help="store internal tracing debug information in 'pytestdebug.log'.")
+    # support for "--overwrite-ini ININAME=INIVALUE" to override values from the ini file
+    # Example '-o xfail_strict=True'.
+    group._addoption('-o', '--override-ini', nargs='*', dest="override_ini", action="append",
+               help="overrides ini values which do not have a separate command-line flag")
 
 
 @pytest.hookimpl(hookwrapper=True)

testing/test_config.py

@@ -583,3 +583,92 @@ def test_with_specific_inifile(self, tmpdir):
         inifile = tmpdir.ensure("pytest.ini")
         rootdir, inifile, inicfg = determine_setup(inifile, [tmpdir])
         assert rootdir == tmpdir
+
+class TestOverrideIniArgs:
+    """ test --override-ini """
+    @pytest.mark.parametrize("name", "setup.cfg tox.ini pytest.ini".split())
+    def test_override_ini_names(self, testdir, name):
+        testdir.tmpdir.join(name).write(py.std.textwrap.dedent("""
+            [pytest]
+            custom = 1.0
+        """))
+        testdir.makeconftest("""
+            def pytest_addoption(parser):
+                parser.addini("custom", "")
+        """)
+        testdir.makepyfile("""
+            def test_pass(pytestconfig):
+                ini_val = pytestconfig.getini("custom")
+                print('\\ncustom_option:%s\\n' % ini_val)
+        """)
+
+        result = testdir.runpytest("--override-ini", "custom=2.0", "-s")
+        assert result.ret == 0
+        result.stdout.fnmatch_lines([
+            "custom_option:2.0"
+        ])
+
+        result = testdir.runpytest("--override-ini", "custom=2.0",
+                                   "--override-ini=custom=3.0", "-s")
+        assert result.ret == 0
+        result.stdout.fnmatch_lines([
+            "custom_option:3.0"
+        ])
+
+
+    def test_override_ini_pathlist(self, testdir):
+        testdir.makeconftest("""
+                def pytest_addoption(parser):
+                    parser.addini("paths", "my new ini value", type="pathlist")
+        """)
+        testdir.makeini("""
+                [pytest]
+                paths=blah.py
+        """)
+        testdir.makepyfile("""
+                import py.path
+                def test_pathlist(pytestconfig):
+                    config_paths = pytestconfig.getini("paths")
+                    print(config_paths)
+                    for cpf in config_paths:
+                        print('\\nuser_path:%s' % cpf.basename)
+        """)
+        result = testdir.runpytest("--override-ini", 'paths=foo/bar1.py foo/bar2.py', "-s")
+        result.stdout.fnmatch_lines([
+            "user_path:bar1.py",
+            "user_path:bar2.py"
+        ])
+
+    def test_override_multiple_and_default(self, testdir):
+        testdir.makeconftest("""
+                def pytest_addoption(parser):
+                    parser.addini("custom_option_1", "", default="o1")
+                    parser.addini("custom_option_2", "", default="o2")
+                    parser.addini("custom_option_3", "", default=False, type="bool")
+                    parser.addini("custom_option_4", "", default=True, type="bool")
+
+        """)
+        testdir.makeini("""
+                [pytest]
+                custom_option_1=custom_option_1
+                custom_option_2=custom_option_2
+        """)
+        testdir.makepyfile("""
+                def test_multiple_options(pytestconfig):
+                    prefix="custom_option"
+                    for x in range(1,5):
+                        ini_value=pytestconfig.getini("%s_%d" % (prefix, x))
+                        print('\\nini%d:%s' % (x, ini_value))
+        """)
+        result = testdir.runpytest("--override-ini",
+                                   'custom_option_1=fulldir=/tmp/user1',
+                                   'custom_option_2=url=/tmp/user2?a=b&d=e',
+                                   "-o", 'custom_option_3=True',
+                                   "-o", 'custom_option_4=no',
+                                   "-s")
+        result.stdout.fnmatch_lines([
+            "ini1:fulldir=/tmp/user1",
+            "ini2:url=/tmp/user2?a=b&d=e",
+            "ini3:True",
+            "ini4:False"
+        ])