Add api doc and update unittest. (#43)

* Add doc strings.
* Update overlap_add op unittest

Author: KPatr1ck

paddle/fluid/operators/overlap_add_op.cc

@@ -44,6 +44,7 @@ class OverlapAddOp : public framework::OperatorWithKernel {
             "Attribute(hop_length) of OverlapAddOp should be greater "
             "than 0, but got %s.",
             hop_length));
+
     PADDLE_ENFORCE_EQ(
         (axis == 0 || axis == -1), true,
         platform::errors::InvalidArgument(
@@ -68,6 +69,13 @@ class OverlapAddOp : public framework::OperatorWithKernel {
       end_axis = x_rank - 3;
     }
 
+    PADDLE_ENFORCE_LE(
+        hop_length, frame_length,
+        platform::errors::InvalidArgument(
+            "Attribute(hop_length) of OverlapAddOp should be less or equal "
+            "than frame_length, but got hop_length(%s) > frame_length(%s).",
+            hop_length, frame_length));
+
     const int seq_length = (n_frames - 1) * hop_length + frame_length;
 
     // It won't go into for loop when x_rank == 2U.

python/paddle/fluid/tests/unittests/test_overlap_add_op.py

@@ -79,10 +79,10 @@ def setUp(self):
         self.outputs = {'Out': overlap_add(x=self.inputs['X'], **self.attrs)}
 
     def initTestCase(self):
-        input_shape = (150, 30)
+        input_shape = (50, 3)
         input_type = 'float64'
         attrs = {
-            'hop_length': 20,
+            'hop_length': 4,
             'axis': -1,
         }
         return input_shape, input_type, attrs
@@ -100,54 +100,54 @@ def test_check_grad_normal(self):
 
 class TestCase1(TestOverlapAddOp):
     def initTestCase(self):
-        input_shape = (30, 150)
+        input_shape = (3, 50)
         input_type = 'float64'
         attrs = {
-            'hop_length': 15,
+            'hop_length': 4,
             'axis': 0,
         }
         return input_shape, input_type, attrs
 
 
 class TestCase2(TestOverlapAddOp):
     def initTestCase(self):
-        input_shape = (2, 250, 10)
+        input_shape = (2, 40, 5)
         input_type = 'float64'
         attrs = {
-            'hop_length': 50,
+            'hop_length': 10,
             'axis': -1,
         }
         return input_shape, input_type, attrs
 
 
 class TestCase3(TestOverlapAddOp):
     def initTestCase(self):
-        input_shape = (10, 250, 2)
+        input_shape = (5, 40, 2)
         input_type = 'float64'
         attrs = {
-            'hop_length': 30,
+            'hop_length': 10,
             'axis': 0,
         }
         return input_shape, input_type, attrs
 
 
 class TestCase4(TestOverlapAddOp):
     def initTestCase(self):
-        input_shape = (3, 5, 70, 20)
+        input_shape = (3, 5, 12, 8)
         input_type = 'float64'
         attrs = {
-            'hop_length': 27,
+            'hop_length': 5,
             'axis': -1,
         }
         return input_shape, input_type, attrs
 
 
 class TestCase5(TestOverlapAddOp):
     def initTestCase(self):
-        input_shape = (20, 70, 5, 3)
+        input_shape = (8, 12, 5, 3)
         input_type = 'float64'
         attrs = {
-            'hop_length': 33,
+            'hop_length': 5,
             'axis': 0,
         }
         return input_shape, input_type, attrs