Fix mappingproxy.get

Author: msimacek

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_types.txt

@@ -22,9 +22,11 @@
 *graalpython.lib-python.3.test.test_types.CoroutineTests.test_non_gen_values
 *graalpython.lib-python.3.test.test_types.CoroutineTests.test_wrapper_object
 *graalpython.lib-python.3.test.test_types.CoroutineTests.test_wrong_args
+*graalpython.lib-python.3.test.test_types.MappingProxyTests.test_chainmap
 *graalpython.lib-python.3.test.test_types.MappingProxyTests.test_constructor
 *graalpython.lib-python.3.test.test_types.MappingProxyTests.test_contains
 *graalpython.lib-python.3.test.test_types.MappingProxyTests.test_copy
+*graalpython.lib-python.3.test.test_types.MappingProxyTests.test_customdict
 *graalpython.lib-python.3.test.test_types.MappingProxyTests.test_get
 *graalpython.lib-python.3.test.test_types.MappingProxyTests.test_iterators
 *graalpython.lib-python.3.test.test_types.MappingProxyTests.test_len

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/mappingproxy/MappingproxyBuiltins.java

@@ -125,7 +125,13 @@ public Object values(VirtualFrame frame, PMappingproxy self,
     @Builtin(name = "get", minNumOfPositionalArgs = 2, maxNumOfPositionalArgs = 3)
     @GenerateNodeFactory
     public abstract static class GetNode extends PythonBuiltinNode {
-        @Specialization(limit = "1")
+        @Specialization(guards = "isNoValue(defaultValue)", limit = "1")
+        public Object get(VirtualFrame frame, PMappingproxy self, Object key, @SuppressWarnings("unused") PNone defaultValue,
+                        @CachedLibrary("self.getMapping()") PythonObjectLibrary lib) {
+            return lib.lookupAndCallRegularMethod(self.getMapping(), frame, "get", key);
+        }
+
+        @Specialization(guards = "!isNoValue(defaultValue)", limit = "1")
         public Object get(VirtualFrame frame, PMappingproxy self, Object key, Object defaultValue,
                         @CachedLibrary("self.getMapping()") PythonObjectLibrary lib) {
             return lib.lookupAndCallRegularMethod(self.getMapping(), frame, "get", key, defaultValue);