Add unitTest for `Tensor==constant` for ifElse in dygraph2static (#23407)

* Add unitTest for `Tensor==constant` for ifElse in dygraph2static test=develop

python/paddle/fluid/dygraph/dygraph_to_static/ifelse_transformer.py

@@ -85,6 +85,7 @@ class IfElseTransformer(gast.NodeTransformer):
             attribute = node.func
             if attribute.attr == 'numpy':
                 node = attribute.value
+        self.generic_visit(node)
         return node
 
     def visit_IfExp(self, node):
@@ -292,12 +293,12 @@ class NodeTestTransformer(gast.NodeTransformer):
         return self.visit(self.ast_root)
 
     def visit_Call(self, node):
-        # self.generic_visit(node)
         # Remove `numpy()` statement, like `Tensor.numpy()[i]` -> `Tensor[i]`
         if isinstance(node.func, gast.Attribute):
             attribute = node.func
             if attribute.attr == 'numpy':
                 node = attribute.value
+        self.generic_visit(node)
         return node
 
     def visit_UnaryOp(self, node):

python/paddle/fluid/tests/unittests/dygraph_to_static/test_ifelse.py

@@ -116,6 +116,30 @@ class TestDygraphIfElse6(TestDygraphIfElse):
         self.dyfunc = dyfunc_ifExp_with_while
 
 
+def dyfunc_ifExp_with_while2(x):
+    y = [x]
+
+    def add_fn(x):
+        x = x + 1
+        return x
+
+    def map_func(func, tensor_list):
+        return [func(x) for x in tensor_list]
+
+    i = fluid.layers.fill_constant(shape=[1], dtype='int64', value=0)
+    # It will be converted into `layers.cond` as followed.
+    # map_func(lambda x: fluid.layers.cond(i==0, lambda: x, lambda: add_fn(x), y)
+    # `i (Tensor) == 0` is supported in dygraph.
+    y = map_func(lambda x: x if i == 0 else add_fn(x), y)
+    return y[0]
+
+
+class TestDygraphIfElse7(TestDygraphIfElse):
+    def setUp(self):
+        self.x = np.random.random([10, 16]).astype('float32')
+        self.dyfunc = dyfunc_ifExp_with_while2
+
+
 class TestDygraphIfElseWithAndOr(TestDygraphIfElse):
     def setUp(self):
         self.x = np.random.random([10, 16]).astype('float32')