Deprecate yield tests

Closes #16
Closes #1324

CHANGELOG.rst

@@ -185,7 +185,8 @@
   Before, you only got exceptions later from ``argparse`` library,
   giving no clue about the actual reason for double-added options.
 
-*
+* ``yield``-based tests are considered deprecated and will be removed in pytest-4.0.
+  Thanks `@nicoddemus`_ for the PR.
 
 *
 

_pytest/python.py

@@ -589,6 +589,8 @@ class Generator(FunctionMixin, PyCollector):
                 raise ValueError("%r generated tests with non-unique name %r" %(self, name))
             seen[name] = True
             l.append(self.Function(name, self, args=args, callobj=call))
+            msg = 'yield tests are deprecated, and scheduled to be removed in pytest 4.0'
+            self.config.warn('C1', msg, fslocation=self.fspath)
         return l
 
     def getcallargs(self, obj):
@@ -611,8 +613,6 @@ def hasinit(obj):
             return True
 
 
-
-
 class CallSpec2(object):
     def __init__(self, metafunc):
         self.metafunc = metafunc

testing/acceptance_test.py

@@ -762,3 +762,18 @@ class TestDurationWithFixture:
             * setup *test_1*
             * call *test_1*
         """)
+
+
+def test_yield_tests_deprecation(testdir):
+    testdir.makepyfile("""
+        def func1(arg, arg2):
+            assert arg == arg2
+        def test_gen():
+            yield "m1", func1, 15, 3*5
+            yield "m2", func1, 42, 6*7
+    """)
+    result = testdir.runpytest('-ra')
+    result.stdout.fnmatch_lines([
+        '*yield tests are deprecated, and scheduled to be removed in pytest 4.0*',
+        '*2 passed*',
+    ])

testing/code/test_source.py

@@ -285,13 +285,14 @@ class TestSourceParsingAndCompiling:
         #print "block", str(block)
         assert str(stmt).strip().startswith('assert')
 
-    def test_compilefuncs_and_path_sanity(self):
+    @pytest.mark.parametrize('name', ['', None, 'my'])
+    def test_compilefuncs_and_path_sanity(self, name):
         def check(comp, name):
             co = comp(self.source, name)
             if not name:
-                expected = "codegen %s:%d>" %(mypath, mylineno+2+1)
+                expected = "codegen %s:%d>" %(mypath, mylineno+2+2)
             else:
-                expected = "codegen %r %s:%d>" % (name, mypath, mylineno+2+1)
+                expected = "codegen %r %s:%d>" % (name, mypath, mylineno+2+2)
             fn = co.co_filename
             assert fn.endswith(expected)
 
@@ -300,8 +301,7 @@ class TestSourceParsingAndCompiling:
         mypath = mycode.path
 
         for comp in _pytest._code.compile, _pytest._code.Source.compile:
-            for name in '', None, 'my':
-                yield check, comp, name
+            check(comp, name)
 
     def test_offsetless_synerr(self):
         pytest.raises(SyntaxError, _pytest._code.compile, "lambda a,a: 0", mode='eval')