Add test with optional enum

Author: roblabla

tests/inputs/proto3_field_presence/proto3_field_presence.json

@@ -1,7 +1,10 @@
 {
-  "test1": null,
-  "test2": null,
-  "test3": null,
-  "test4": null,
-  "test5": null
+  "test1": 128,
+  "test2": true,
+  "test3": "A value",
+  "test4": "aGVsbG8=",
+  "test5": {
+    "test": "Hello"
+  },
+  "test6": "B"
 }

tests/inputs/proto3_field_presence/proto3_field_presence.proto

@@ -10,4 +10,10 @@ message Test {
     optional string test3 = 3;
     optional bytes test4 = 4;
     optional InnerTest test5 = 5;
+    optional TestEnum test6 = 6;
+}
+
+enum TestEnum {
+    A = 0;
+    B = 1;
 }

tests/inputs/proto3_field_presence/proto3_field_presence_default.json

@@ -0,0 +1,8 @@
+{
+  "test1": null,
+  "test2": null,
+  "test3": null,
+  "test4": null,
+  "test5": null,
+  "test6": null
+}

tests/inputs/proto3_field_presence/proto3_field_presence_missing.json

@@ -0,0 +1,8 @@
+{
+  "test1": 0,
+  "test2": false,
+  "test3": "",
+  "test4": "",
+  "test5": null,
+  "test6": "A"
+}