Issue: 3103 - Fix UsageError raised when specifying config override options followed by test path

AUTHORS

@@ -17,6 +17,7 @@ Anthon van der Neut
 Anthony Sottile
 Antony Lee
 Armin Rigo
+Aron Coyle
 Aron Curzon
 Aviv Palivoda
 Barney Gale

_pytest/config.py

@@ -1191,12 +1191,15 @@ def _get_override_ini_value(self, name):
         # 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
+        first_override_set = False
         for ini_config_list in self._override_ini:
             for ini_config in ini_config_list:
                 try:
                     (key, user_ini_value) = ini_config.split("=", 1)
+                    first_override_set = True
                 except ValueError:
-                    raise UsageError("-o/--override-ini expects option=value style.")
+                    if not first_override_set:
+                        raise UsageError("-o/--override-ini expects option=value style.")
                 if key == name:
                     value = user_ini_value
         return value

changelog/3103.bugfix

@@ -0,0 +1 @@
+Fix ``UsageError`` being raised when specifying ``-o/--override`` command-line option followed by a test path.

testing/test_config.py

@@ -860,3 +860,17 @@ def test_addopts_before_initini(self, testdir, tmpdir, monkeypatch):
         config = get_config()
         config._preparse([], addopts=True)
         assert config._override_ini == [['cache_dir=%s' % cache_dir]]
+
+    def test_no_error_if_true_first_key_value_pair(self, testdir, request):
+        """Ensure a file path following a '-o' option does not generate an error (#3103)"""
+        testdir.makeini("""
+            [pytest]
+            xdist_strict=False
+        """)
+        testdir.makepyfile("""
+            def test():
+                pass
+        """)
+        result = testdir.runpytest('--override-ini', 'xdist_strict=True', '{}.py'.format(request.node.name))
+        assert 'ERROR:' not in result.stderr.str()
+        result.stdout.fnmatch_lines('* 1 passed in *')