added comment re: gemv dtype testing

theano/tensor/tests/test_blas_c.py

@@ -92,6 +92,12 @@ class TestCGer(TestCase, TestOptimizationMixin):
 
 
 class TestCGemv(TestCase, TestOptimizationMixin):
+    """
+    Tests of CGemv specifically.
+
+    Generic tests of Gemv-compatibility, including both dtypes are done below in
+    TestCGemvFloat32 and TestCGemvFloat64
+    """
     def setUp(self, dtype='float64'):
         self.dtype = dtype
         self.mode = theano.compile.get_default_mode().including('fast_run')