[WIP] Allow developers of plugins and pytest to use code objects

src/_pytest/pytester.py

@@ -3,6 +3,7 @@
 
 import codecs
 import gc
+import inspect
 import os
 import platform
 import re
@@ -584,6 +585,19 @@ def makepyfile(self, *args, **kwargs):
         """Shortcut for .makefile() with a .py extension."""
         return self._makefile(".py", args, kwargs)
 
+    def makepyfilefunc(self, func, *args, **kwargs):
+        """Make Python file from function"""
+        source = inspect.getsourcelines(func)[0][1:]
+        # Calculate whitespace from function and remove it.
+        pad = 0
+        for c in source[0]:
+            if c == ' ':
+                pad += 1
+            else:
+                break
+        unpadded_source = ''.join([line[pad:] for line in source])
+        return self.makepyfile(unpadded_source)
+
     def maketxtfile(self, *args, **kwargs):
         """Shortcut for .makefile() with a .txt extension."""
         return self._makefile(".txt", args, kwargs)

testing/test_pytester.py

@@ -140,6 +140,17 @@ def setup_function(function):
     assert u"mixed_encoding = u'São Paulo'".encode("utf-8") in p.read("rb")
 
 
+def test_makepyfilefunc(testdir):
+    """Test makepyfilefunc against an inline function declaration"""
+    def tests():
+        def test_foo():
+            assert True
+
+    test_mod = testdir.makepyfilefunc(tests)
+    result = testdir.inline_run(str(test_mod))
+    assert result.ret == EXIT_OK
+
+
 class TestInlineRunModulesCleanup(object):
     def test_inline_run_test_module_not_cleaned_up(self, testdir):
         test_mod = testdir.makepyfile("def test_foo(): assert True")