Added comments. Added test that rejects non-string keys

theano/tests/test_dictionary_output.py

 import unittest
 import theano
 import theano.tensor as T
-import sys
 
 
 class dictionary_output_checker(unittest.TestCase):
 
     def test_output_dictionary(self):
+
+        '''
+        Tests that theano.function works when outputs is a dictionary
+        '''
+
         x = T.scalar()
         f = theano.function([x], outputs={'a': x, 'c': x*2,
                                           'b': x*3, '1': x*4})
@@ -19,6 +23,11 @@ class dictionary_output_checker(unittest.TestCase):
         assert outputs['c'] == 20.0
 
     def test_input_named_variables(self):
+
+        '''
+        Tests that named variables work when outputs is a dictionary
+        '''
+
         x = T.scalar('x')
         y = T.scalar('y')
 
@@ -29,6 +38,11 @@ class dictionary_output_checker(unittest.TestCase):
         assert f(x=2, y=4) == f(2, 4)
 
     def test_output_order_sorted(self):
+
+        '''
+        Tests that the output keys are sorted correctly.
+        '''
+
         x = T.scalar('x')
         y = T.scalar('y')
         z = T.scalar('z')
@@ -45,6 +59,12 @@ class dictionary_output_checker(unittest.TestCase):
         assert 'z' in str(f.outputs[4])
 
     def test_composing_function(self):
+
+        '''
+        Tests that one can compose two theano functions when the outputs are
+        provided in a dictionary.
+        '''
+
         x = T.scalar('x')
         y = T.scalar('y')
 
@@ -68,6 +88,10 @@ class dictionary_output_checker(unittest.TestCase):
 
     def test_output_list_still_works(self):
 
+        '''
+        Test that theano.function works if outputs is a list.
+        '''
+
         x = T.scalar('x')
 
         f = theano.function([x], outputs=[x * 3, x * 2, x * 4, x])
@@ -80,9 +104,12 @@ class dictionary_output_checker(unittest.TestCase):
         assert result[3] == 5.0
 
     def test_debug_mode_dict(self):
-        x = T.scalar('x')
 
-        print sys.stderr, "Running debug mode with dict"
+        '''
+        Tests that debug mode works where outputs is a dictionary.
+        '''
+
+        x = T.scalar('x')
 
         f = theano.function([x], outputs={'1': x, '2': 2 * x,
                                           '3': 3 * x}, mode="DEBUG_MODE")
@@ -95,12 +122,42 @@ class dictionary_output_checker(unittest.TestCase):
 
     def test_debug_mode_list(self):
 
+        '''
+        Tests that debug mode works where the outputs argument is a list.
+        '''
+
         x = T.scalar('x')
 
-        f = theano.function([x], outputs=[x, 2 * x, 3 * x])
+        f = theano.function([x], outputs=[x, 2 * x, 3 * x], mode="DEBUG_MODE")
 
         result = f(5.0)
 
         assert result[0] == 5.0
         assert result[1] == 10.0
         assert result[2] == 15.0
+
+    def test_key_string_requirement(self):
+        '''
+        Tests that an exception is thrown if a non-string key is used in
+        the outputs dictionary.
+        '''
+
+        x = T.scalar('x')
+
+        try:
+            theano.function([x], outputs={1.0: x})
+            raise Exception("Did not throw exception with 1.0 as only key")
+        except AssertionError:
+            pass
+
+        try:
+            theano.function([x], outputs={1.0: x, "a": x**2})
+            raise Exception("Did not throw exception with 1.0 as one key")
+        except AssertionError:
+            pass
+
+        try:
+            theano.function([x], outputs={("a", "b"): x, "a": x**2})
+            raise Exception("Did not throw exception with tuple as one key")
+        except AssertionError:
+            pass