Add new testdirs ini option

Fix #694

CHANGELOG

@@ -6,6 +6,13 @@
   or no tests were run at all (this is a partial fix for issue500). 
   Thanks Eric Siegerman.
 
+- New `testdirs` ini option: list of directories to search for tests
+  when executing pytest from the root directory. This can be used
+  to speed up test collection when a project has well specified directories
+  for tests, being usually more practical than configuring norecursedirs for
+  all directories that do not contain tests.
+  Thanks to Adrian for idea (#694) and Bruno Oliveira for the PR.
+
 - fix issue713: JUnit XML reports for doctest failures.
   Thanks Punyashloka Biswal.
 

_pytest/config.py

@@ -917,7 +917,11 @@ class Config(object):
         self.hook.pytest_cmdline_preparse(config=self, args=args)
         args = self._parser.parse_setoption(args, self.option)
         if not args:
-            args.append(os.getcwd())
+            cwd = os.getcwd()
+            if cwd == self.rootdir:
+                args = self.getini('testpaths')
+            if not args:
+                args = [cwd]
         self.args = args
 
     def addinivalue_line(self, name, line):

_pytest/main.py

@@ -25,6 +25,8 @@ name_re = re.compile("^[a-zA-Z_]\w*$")
 def pytest_addoption(parser):
     parser.addini("norecursedirs", "directory patterns to avoid for recursion",
         type="args", default=['.*', 'CVS', '_darcs', '{arch}', '*.egg'])
+    parser.addini("testpaths", "directories to search for tests when no files or directories are given in the command line.",
+        type="args", default=[])
     #parser.addini("dirpatterns",
     #    "patterns specifying possible locations of test files",
     #    type="linelist", default=["**/test_*.txt",

doc/en/customize.txt

@@ -157,6 +157,25 @@ Builtin configuration file options
    This would tell ``pytest`` to not look into typical subversion or
    sphinx-build directories or into any ``tmp`` prefixed directory.
 
+.. confval:: testpaths
+
+   .. versionadded:: 2.8
+
+   Sets list of directories that should be searched for tests when
+   no specific directories or files are given in the command line when
+   executing pytest from the :ref:`rootdir <rootdir>` directory.
+   Useful when all project tests are in a known location to speed up
+   test collection and to avoid picking up undesired tests by accident.
+
+   .. code-block:: ini
+
+        # content of pytest.ini
+        [pytest]
+        testpaths = testing doc
+
+   This tells pytest to only look for tests in ``testing`` and ``doc``
+   directories when executing from the root directory.
+
 .. confval:: python_files
 
    One or more Glob-style file patterns determining which python files

doc/en/goodpractises.txt

@@ -282,8 +282,11 @@ Conventions for Python test discovery
 
 ``pytest`` implements the following standard test discovery:
 
-* collection starts from the initial command line arguments
-  which may be directories, filenames or test ids.
+* collection starts from paths specified in :confval:`testpaths` if configured,
+  otherwise from initial command line arguments which may be directories,
+  filenames or test ids. If :confval:`testpaths` is not configured and no
+  directories or files were given in the command line, start collection from
+  the current directory.
 * recurse into directories, unless they match :confval:`norecursedirs`
 * ``test_*.py`` or ``*_test.py`` files, imported by their `test package name`_.
 * ``Test`` prefixed test classes (without an ``__init__`` method)

testing/test_collection.py

@@ -116,6 +116,35 @@ class TestCollectFS:
         rec = testdir.inline_run("xyz123/test_2.py")
         rec.assertoutcome(failed=1)
 
+    def test_testpaths_ini(self, testdir, monkeypatch):
+        testdir.makeini("""
+            [pytest]
+            testpaths = gui uts
+        """)
+        tmpdir = testdir.tmpdir
+        tmpdir.ensure("env", "test_1.py").write("def test_env(): pass")
+        tmpdir.ensure("gui", "test_2.py").write("def test_gui(): pass")
+        tmpdir.ensure("uts", "test_3.py").write("def test_uts(): pass")
+
+        # executing from rootdir only tests from `testpaths` directories
+        # are collected
+        items, reprec = testdir.inline_genitems('-v')
+        assert [x.name for x in items] == ['test_gui', 'test_uts']
+
+        # check that explicitly passing directories in the command-line
+        # collects the tests
+        for dirname in ('env', 'gui', 'uts'):
+            items, reprec = testdir.inline_genitems(tmpdir.join(dirname))
+            assert [x.name for x in items] == ['test_%s' % dirname]
+
+        # changing cwd to each subdirectory and running pytest without
+        # arguments collects the tests in that directory normally
+        for dirname in ('env', 'gui', 'uts'):
+            monkeypatch.chdir(testdir.tmpdir.join(dirname))
+            items, reprec = testdir.inline_genitems()
+            assert [x.name for x in items] == ['test_%s' % dirname]
+
+
 class TestCollectPluginHookRelay:
     def test_pytest_collect_file(self, testdir):
         wascalled = []