Use a subdirectory in the TEMP directory to speed up tmpdir creation

Fix #105

CHANGELOG

@@ -4,6 +4,13 @@
 - fix issue768: docstrings found in python modules were not setting up session
   fixtures. Thanks Jason R. Coombs for reporting and Bruno Oliveira for the PR.
 
+- added `tmpdir_factory`, a session-scoped fixture that can be used to create
+  directories under the base temporary directory. Previously this object was
+  installed as a `_tmpdirhandler` attribute of the `config` object, but now it
+  is part of the official API and using `config._tmpdirhandler` is
+  deprecated.
+  Thanks Bruno Oliveira for the PR.
+
 - fix issue 808: pytest's internal assertion rewrite hook now implements the
   optional PEP302 get_data API so tests can access data files next to them.
   Thanks xmo-odoo for request and example and Bruno Oliveira for

_pytest/pytester.py

@@ -309,16 +309,18 @@ class HookRecorder:
         self.calls[:] = []
 
 
-def pytest_funcarg__linecomp(request):
+@pytest.fixture
+def linecomp(request):
     return LineComp()
 
+
 def pytest_funcarg__LineMatcher(request):
     return LineMatcher
 
-def pytest_funcarg__testdir(request):
-    tmptestdir = Testdir(request)
-    return tmptestdir
 
+@pytest.fixture
+def testdir(request, tmpdir_factory):
+    return Testdir(request, tmpdir_factory)
 
 
 rex_outcome = re.compile("(\d+) (\w+)")
@@ -388,10 +390,10 @@ class Testdir:
 
     """
 
-    def __init__(self, request):
+    def __init__(self, request, tmpdir_factory):
         self.request = request
         # XXX remove duplication with tmpdir plugin
-        basetmp = request.config._tmpdirhandler.ensuretemp("testdir")
+        basetmp = tmpdir_factory.ensuretemp("testdir")
         name = request.function.__name__
         for i in range(100):
             try:

_pytest/tmpdir.py

@@ -6,7 +6,12 @@ import py
 from _pytest.monkeypatch import monkeypatch
 
 
-class TempdirHandler:
+class TempdirFactory:
+    """Factory for temporary directories under the common base temp directory.
+
+    The base directory can be configured using the ``--basetemp`` option.
+    """
+
     def __init__(self, config):
         self.config = config
         self.trace = config.trace.get("tmpdir")
@@ -22,6 +27,10 @@ class TempdirHandler:
         return self.getbasetemp().ensure(string, dir=dir)
 
     def mktemp(self, basename, numbered=True):
+        """Create a subdirectory of the base temporary directory and return it.
+        If ``numbered``, ensure the directory is unique by adding a number
+        prefix greater than any existing one.
+        """
         basetemp = self.getbasetemp()
         if not numbered:
             p = basetemp.mkdir(basename)
@@ -51,15 +60,33 @@ class TempdirHandler:
     def finish(self):
         self.trace("finish")
 
+# backward compatibility
+TempdirHandler = TempdirFactory
+
+
 def pytest_configure(config):
+    """Create a TempdirFactory and attach it to the config object.
+
+    This is to comply with existing plugins which expect the handler to be
+    available at pytest_configure time, but ideally should be moved entirely
+    to the tmpdir_factory session fixture.
+    """
     mp = monkeypatch()
-    t = TempdirHandler(config)
+    t = TempdirFactory(config)
     config._cleanup.extend([mp.undo, t.finish])
     mp.setattr(config, '_tmpdirhandler', t, raising=False)
     mp.setattr(pytest, 'ensuretemp', t.ensuretemp, raising=False)
 
+
+@pytest.fixture(scope='session')
+def tmpdir_factory(request):
+    """Return a TempdirFactory instance for the test session.
+    """
+    return request.config._tmpdirhandler
+
+
 @pytest.fixture
-def tmpdir(request):
+def tmpdir(request, tmpdir_factory):
     """return a temporary directory path object
     which is unique to each test function invocation,
     created as a sub directory of the base temporary
@@ -71,5 +98,5 @@ def tmpdir(request):
     MAXVAL = 30
     if len(name) > MAXVAL:
         name = name[:MAXVAL]
-    x = request.config._tmpdirhandler.mktemp(name, numbered=True)
+    x = tmpdir_factory.mktemp(name, numbered=True)
     return x

doc/en/tmpdir.txt

@@ -5,10 +5,10 @@
 Temporary directories and files
 ================================================
 
-The 'tmpdir' test function argument
+The 'tmpdir' fixture
------------------------------------
+--------------------
 
-You can use the ``tmpdir`` function argument which will
+You can use the ``tmpdir`` fixture which will
 provide a temporary directory unique to the test invocation,
 created in the `base temporary directory`_.
 
@@ -51,6 +51,44 @@ Running this would result in a passed test except for the last
     test_tmpdir.py:7: AssertionError
     ======= 1 failed in 0.12 seconds ========
 
+
+The 'tmpdir_factory' fixture
+----------------------------
+
+.. versionadded:: 2.8
+
+The ``tmpdir_factory`` is a session-scoped fixture which can be used
+to create arbitrary temporary directories from any other fixture or test.
+
+For example, suppose your test suite needs a large image on disk, which is
+generated procedurally. Instead of computing the same image for each test
+that uses it into its own ``tmpdir``, you can generate it once per-session
+to save time:
+
+.. code-block:: python
+
+    # contents of conftest.py
+    import pytest
+
+    @pytest.fixture(scope='session')
+    def image_file(tmpdir_factory):
+        img = compute_expensive_image()
+        fn = tmpdir_factory.mktemp('data').join('img.png')
+        img.save(str(fn))
+        return fn
+
+    # contents of test_image.py
+    def test_histogram(image_file):
+        img = load_image(image_file)
+        # compute and test histogram
+
+``tmpdir_factory`` instances have the following methods:
+
+.. currentmodule:: _pytest.tmpdir
+
+.. automethod:: TempdirFactory.mktemp
+.. automethod:: TempdirFactory.getbasetemp
+
 .. _`base temporary directory`:
 
 The default base temporary directory

testing/python/fixture.py

@@ -555,7 +555,8 @@ class TestRequestBasic:
                 pass
             def test_function(request, farg):
                 assert set(get_public_names(request.fixturenames)) == \
-                       set(["tmpdir", "sarg", "arg1", "request", "farg"])
+                       set(["tmpdir", "sarg", "arg1", "request", "farg",
+                            "tmpdir_factory"])
         """)
         reprec = testdir.inline_run()
         reprec.assertoutcome(passed=1)

testing/test_conftest.py

@@ -4,9 +4,9 @@ from _pytest.config import PytestPluginManager
 
 
 @pytest.fixture(scope="module", params=["global", "inpackage"])
-def basedir(request):
+def basedir(request, tmpdir_factory):
     from _pytest.tmpdir import tmpdir
-    tmpdir = tmpdir(request)
+    tmpdir = tmpdir(request, tmpdir_factory)
     tmpdir.ensure("adir/conftest.py").write("a=1 ; Directory = 3")
     tmpdir.ensure("adir/b/conftest.py").write("b=2 ; a = 1.5")
     if request.param == "inpackage":

testing/test_tmpdir.py

@@ -1,7 +1,7 @@
 import py
 import pytest
 
-from _pytest.tmpdir import tmpdir, TempdirHandler
+from _pytest.tmpdir import tmpdir, TempdirFactory
 
 def test_funcarg(testdir):
     testdir.makepyfile("""
@@ -13,16 +13,15 @@ def test_funcarg(testdir):
     reprec = testdir.inline_run()
     calls = reprec.getcalls("pytest_runtest_setup")
     item = calls[0].item
-    # pytest_unconfigure has deleted the TempdirHandler already
     config = item.config
-    config._tmpdirhandler = TempdirHandler(config)
+    tmpdirhandler = TempdirFactory(config)
     item._initrequest()
-    p = tmpdir(item._request)
+    p = tmpdir(item._request, tmpdirhandler)
     assert p.check()
     bn = p.basename.strip("0123456789")
     assert bn.endswith("test_func_a_")
     item.name = "qwe/\\abc"
-    p = tmpdir(item._request)
+    p = tmpdir(item._request, tmpdirhandler)
     assert p.check()
     bn = p.basename.strip("0123456789")
     assert bn == "qwe__abc"
@@ -38,7 +37,7 @@ class TestTempdirHandler:
     def test_mktemp(self, testdir):
         config = testdir.parseconfig()
         config.option.basetemp = testdir.mkdir("hello")
-        t = TempdirHandler(config)
+        t = TempdirFactory(config)
         tmp = t.mktemp("world")
         assert tmp.relto(t.getbasetemp()) == "world0"
         tmp = t.mktemp("this")
@@ -49,17 +48,19 @@ class TestTempdirHandler:
 
 class TestConfigTmpdir:
     def test_getbasetemp_custom_removes_old(self, testdir):
-        p = testdir.tmpdir.join("xyz")
+        mytemp = testdir.tmpdir.join("xyz")
-        config = testdir.parseconfigure("--basetemp=xyz")
+        p = testdir.makepyfile("""
-        b = config._tmpdirhandler.getbasetemp()
+            def test_1(tmpdir):
-        assert b == p
+                pass
-        h = b.ensure("hello")
+        """)
-        config._tmpdirhandler.getbasetemp()
+        testdir.runpytest(p, '--basetemp=%s' % mytemp)
-        assert h.check()
+        mytemp.check()
-        config = testdir.parseconfigure("--basetemp=xyz")
+        mytemp.ensure("hello")
-        b2 = config._tmpdirhandler.getbasetemp()
+
-        assert b2.check()
+        testdir.runpytest(p, '--basetemp=%s' % mytemp)
-        assert not h.check()
+        mytemp.check()
+        assert not mytemp.join("hello").check()
+
 
 def test_basetemp(testdir):
     mytemp = testdir.tmpdir.mkdir("mytemp")