Add support for `empty` YANG leaf type

Change-Id: I87eafae9df9accdaa4579ace769996e70da6cb1c
diff --git a/tests/leaf_editing.cpp b/tests/leaf_editing.cpp
index 64abbf2..666c975 100644
--- a/tests/leaf_editing.cpp
+++ b/tests/leaf_editing.cpp
@@ -70,7 +70,9 @@
         yang::TypeInfo{createEnum({"wlan0", "wlan1"})},
         yang::TypeInfo{yang::LeafRef{"/mod:portSettings/mod:port", std::make_unique<yang::TypeInfo>(schema->leafType("/mod:portSettings/mod:port"))}},
         yang::TypeInfo{yang::LeafRef{"/mod:activeMappedPort", std::make_unique<yang::TypeInfo>(schema->leafType("/mod:activeMappedPort"))}},
+        yang::TypeInfo{yang::Empty{}},
     }});
+    schema->addLeaf("/", "mod:dummy", yang::Empty{});
 
     Parser parser(schema);
     std::string input;
@@ -325,6 +327,10 @@
                             expected.m_data = enum_("utf3");
                         }
                     }
+                    SECTION("4. empty")
+                    {
+                        expected.m_data = empty_{};
+                    }
                 }
             }
 
@@ -448,6 +454,12 @@
                     expected.m_data = identityRef_{"pizza"};
                 }
             }
+            SECTION("empty")
+            {
+                input = "set mod:dummy ";
+                expected.m_path.m_nodes.push_back(dataNode_{module_{"mod"}, leaf_("dummy")});
+                expected.m_data = empty_{};
+            }
         }
 
         command_ command = parser.parseCommand(input, errorStream);
@@ -584,6 +596,11 @@
             input = "set mod:intOrString true";
         }
 
+        SECTION("no space for empty data")
+        {
+            input = "set mod:dummy";
+        }
+
         REQUIRE_THROWS_AS(parser.parseCommand(input, errorStream), InvalidCommandException);
         REQUIRE(errorStream.str().find(expectedError) != std::string::npos);
     }