Switch some dy2st UT to eager mode (#41052)

* Switch some dy2st UT to eager mode

* Add UT

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

@@ -262,4 +262,5 @@ def init_dygraph_func(self):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with fluid.framework._test_eager_guard():
+        unittest.main()

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

@@ -425,4 +425,5 @@ def test_ast_to_func(self):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with paddle.fluid.framework._test_eager_guard():
+        unittest.main()

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

@@ -421,4 +421,5 @@ def test_ast_to_func(self):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with fluid.framework._test_eager_guard():
+        unittest.main()

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

@@ -91,4 +91,5 @@ def train(self, to_static=False):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with paddle.fluid.framework._test_eager_guard():
+        unittest.main()

python/paddle/fluid/tests/unittests/dygraph_to_static/test_mnist_pure_fp16.py

@@ -108,4 +108,5 @@ def train(self, to_static=False):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with paddle.fluid.framework._test_eager_guard():
+        unittest.main()

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

@@ -213,4 +213,5 @@ def test_train(self):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with fluid.framework._test_eager_guard():
+        unittest.main()

python/paddle/fluid/tests/unittests/dygraph_to_static/test_yolov3.py

@@ -170,4 +170,5 @@ def test_dygraph_static_same_loss(self):
 
 
 if __name__ == '__main__':
-    unittest.main()
+    with fluid.framework._test_eager_guard():
+        unittest.main()