From bec9933f844c8da14d2c626a994d2918efd34663 Mon Sep 17 00:00:00 2001
From: orange-buffalo <orange-buffalo@users.noreply.github.com>
Date: Mon, 10 Jan 2022 18:48:19 +1100
Subject: [PATCH] Fixing false positive breaking change reported when removing
 an optional field from a response. Closes #198

---
 .../openapitools/openapidiff/core/model/ChangedSchema.java | 7 ++++++-
 .../org/openapitools/openapidiff/core/AddPropDiffTest.java | 4 ++--
 core/src/test/resources/recursive_model_1.yaml             | 3 ++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/org/openapitools/openapidiff/core/model/ChangedSchema.java b/core/src/main/java/org/openapitools/openapidiff/core/model/ChangedSchema.java
index c6289f17d..22e5a8f08 100644
--- a/core/src/main/java/org/openapitools/openapidiff/core/model/ChangedSchema.java
+++ b/core/src/main/java/org/openapitools/openapidiff/core/model/ChangedSchema.java
@@ -137,8 +137,13 @@ private DiffResult calculateCoreChanged() {
         && !discriminatorPropertyChanged) {
       return DiffResult.NO_CHANGES;
     }
+    boolean missingRequiredProperties =
+        oldSchema != null
+            && oldSchema.getRequired() != null
+            && missingProperties.keySet().stream()
+                .anyMatch(missingProperty -> oldSchema.getRequired().contains(missingProperty));
     boolean compatibleForResponse =
-        missingProperties.isEmpty() && (oldSchema == null || newSchema != null);
+        !missingRequiredProperties && (oldSchema == null || newSchema != null);
     if ((context.isRequest() && compatibleForRequest()
             || context.isResponse() && compatibleForResponse)
         && !changedType
diff --git a/core/src/test/java/org/openapitools/openapidiff/core/AddPropDiffTest.java b/core/src/test/java/org/openapitools/openapidiff/core/AddPropDiffTest.java
index b71d8f039..6d668c115 100644
--- a/core/src/test/java/org/openapitools/openapidiff/core/AddPropDiffTest.java
+++ b/core/src/test/java/org/openapitools/openapidiff/core/AddPropDiffTest.java
@@ -1,7 +1,7 @@
 package org.openapitools.openapidiff.core;
 
 import static org.openapitools.openapidiff.core.TestUtils.assertOpenApiAreEquals;
-import static org.openapitools.openapidiff.core.TestUtils.assertOpenApiBackwardIncompatible;
+import static org.openapitools.openapidiff.core.TestUtils.assertOpenApiBackwardCompatible;
 
 import org.junit.jupiter.api.Test;
 
@@ -16,6 +16,6 @@ public void testDiffSame() {
 
   @Test
   public void testDiffDifferent() {
-    assertOpenApiBackwardIncompatible(OPENAPI_DOC1, OPENAPI_DOC2);
+    assertOpenApiBackwardCompatible(OPENAPI_DOC1, OPENAPI_DOC2, true);
   }
 }
diff --git a/core/src/test/resources/recursive_model_1.yaml b/core/src/test/resources/recursive_model_1.yaml
index 6a05ab0ad..24f545186 100644
--- a/core/src/test/resources/recursive_model_1.yaml
+++ b/core/src/test/resources/recursive_model_1.yaml
@@ -19,6 +19,7 @@ components:
   schemas:
     B:
       type: object
+      required: ["message2"]
       properties:
         message:
           type: string
@@ -27,4 +28,4 @@ components:
         details:
           type: array
           items:
-            $ref: '#/components/schemas/B'
\ No newline at end of file
+            $ref: '#/components/schemas/B'