feature: default behavior now is to ignore duplicate paths specified from the command line. Use --keep-duplicates to retain duplicate paths.

AUTHORS

@@ -95,6 +95,7 @@ Punyashloka Biswal
 Quentin Pradet
 Ralf Schmitt
 Raphael Pierzina
+Roberto Polli
 Romain Dorgueil
 Roman Bolshakov
 Ronny Pfannschmidt

CHANGELOG.rst

@@ -120,8 +120,11 @@ time or change existing behaviors in order to make them less surprising/more use
     fixtures and reports them;
   + ``--setup-show``: performs normal test execution and additionally shows
     setup and teardown of fixtures;
+  + ``--keep-duplicates``: default behavior is now to ignore duplicate paths, you can  
+    retain the old behavior and running multiple times the tests  
+    using the ``--keep-duplicates`` cli argument `#1609`_;
 
-  Thanks `@d6e`_, `@kvas-it`_, `@sallner`_ and `@omarkohl`_ for the PRs.
+  Thanks `@d6e`_, `@kvas-it`_, `@sallner`_, `@ioggstream`_ and `@omarkohl`_ for the PRs.
 
 * New CLI flag ``--override-ini``/``-o``: overrides values from the ini file.
   For example: ``"-o xfail_strict=True"``'.
@@ -524,6 +527,7 @@ time or change existing behaviors in order to make them less surprising/more use
 
 .. _`traceback style docs`: https://pytest.org/latest/usage.html#modifying-python-traceback-printing
 
+.. _#1609: https://github.com/pytest-dev/pytest/issues/1609
 .. _#1422: https://github.com/pytest-dev/pytest/issues/1422
 .. _#1379: https://github.com/pytest-dev/pytest/issues/1379
 .. _#1366: https://github.com/pytest-dev/pytest/issues/1366
@@ -549,6 +553,7 @@ time or change existing behaviors in order to make them less surprising/more use
 .. _@rabbbit: https://github.com/rabbbit
 .. _@hackebrot: https://github.com/hackebrot
 .. _@pquentin: https://github.com/pquentin
+.. _@ioggstream: https://github.com/ioggstream
 
 2.8.7
 =====

_pytest/config.py

@@ -155,6 +155,7 @@ class PytestPluginManager(PluginManager):
         self._conftestpath2mod = {}
         self._confcutdir = None
         self._noconftest = False
+        self._duplicatepaths = set()
 
         self.add_hookspecs(_pytest.hookspec)
         self.register(self)

_pytest/main.py

@@ -63,6 +63,9 @@ def pytest_addoption(parser):
     group.addoption('--noconftest', action="store_true",
         dest="noconftest", default=False,
         help="Don't load any conftest.py files.")
+    group.addoption('--keepduplicates', '--keep-duplicates', action="store_true",
+        dest="keepduplicates", default=False,
+        help="Skip duplicate tests.")
 
     group = parser.getgroup("debugconfig",
         "test session debugging and configuration")
@@ -154,7 +157,25 @@ def pytest_ignore_collect(path, config):
     excludeopt = config.getoption("ignore")
     if excludeopt:
         ignore_paths.extend([py.path.local(x) for x in excludeopt])
-    return path in ignore_paths
+
+    if path in ignore_paths:
+        return True
+
+    # Skip duplicate paths.
+    #  TODO: is this called when specifying direct filenames
+    #        from command lines, eg.
+    #        py.test test_a.py test_b.py
+    keepduplicates = config.getoption("keepduplicates")
+    duplicate_paths = config.pluginmanager._duplicatepaths
+    if not keepduplicates:
+        if path in duplicate_paths:
+            #  TODO should we log this?
+            return True
+        else:
+            duplicate_paths.add(path)
+
+    return False
+
 
 class FSHookProxy:
     def __init__(self, fspath, pm, remove_mods):

doc/en/example/pythoncollection.rst

@@ -40,6 +40,40 @@ you will see that ``pytest`` only collects test-modules, which do not match the
     ======= 5 passed in 0.02 seconds =======
 
 
+Keeping duplicate paths specified from command line
+----------------------------------------------------
+
+Default behavior of ``pytest`` is to ignore duplicate paths specified from the command line.
+Example::
+
+    py.test path_a path_a
+
+    ...
+    collected 1 item
+    ...
+
+Just collect tests once.
+
+To collect duplicate tests, use the ``--keep-duplicates`` option on the cli.
+Example::
+
+    py.test --keep-duplicates path_a path_a
+
+    ...
+    collected 2 items
+    ...
+
+As the collector just works on directories, if you specify twice a single test file, ``pytest`` will
+still collect it twice, no matter if the ``--keep-duplicates`` is not specified.
+Example::
+
+    py.test test_a.py test_a.py
+
+    ...
+    collected 2 items
+    ...
+
+
 Changing directory recursion
 -----------------------------------------------------
 

testing/python/collect.py

@@ -1213,3 +1213,40 @@ def test_syntax_error_with_non_ascii_chars(testdir):
         '*SyntaxError*',
         '*1 error in*',
     ])
+
+
+def test_skip_duplicates_by_default(testdir):
+    """Test for issue https://github.com/pytest-dev/pytest/issues/1609 (#1609)
+
+    Ignore duplicate directories.
+    """
+    a = testdir.mkdir("a")
+    fh = a.join("test_a.py")
+    fh.write(_pytest._code.Source("""
+        import pytest
+        def test_real():
+            pass
+    """))
+    result = testdir.runpytest(a.strpath, a.strpath)
+    result.stdout.fnmatch_lines([
+        '*collected 1 item*',
+    ])
+
+
+
+def test_keep_duplicates(testdir):
+    """Test for issue https://github.com/pytest-dev/pytest/issues/1609 (#1609)
+
+    Use --keep-duplicates to collect tests from duplicate directories.
+    """
+    a = testdir.mkdir("a")
+    fh = a.join("test_a.py")
+    fh.write(_pytest._code.Source("""
+        import pytest
+        def test_real():
+            pass
+    """))
+    result = testdir.runpytest("--keep-duplicates", a.strpath, a.strpath)
+    result.stdout.fnmatch_lines([
+        '*collected 2 item*',
+    ])

testing/python/metafunc.py

@@ -973,7 +973,7 @@ class TestMetafuncFunctional:
         """))
         sub1.join("test_in_sub1.py").write("def test_1(): pass")
         sub2.join("test_in_sub2.py").write("def test_2(): pass")
-        result = testdir.runpytest("-v", "-s", sub1, sub2, sub1)
+        result = testdir.runpytest("--keep-duplicates", "-v", "-s", sub1, sub2, sub1)
         result.assert_outcomes(passed=3)
 
     def test_generate_same_function_names_issue403(self, testdir):