fix #461: add minlength breaking change detection

Author: dhananjay12

core/src/main/java/org/openapitools/openapidiff/core/model/BackwardIncompatibleProp.java

@@ -14,7 +14,7 @@ public enum BackwardIncompatibleProp {
   REQUEST_CONTENT_DECREASED("incompatible.request.content.decreased", true),
   REQUEST_ENUM_DECREASED("incompatible.request.enum.decreased", true),
   REQUEST_MAX_LENGTH_DECREASED("incompatible.request.max.length.decreased", true),
-  REQUEST_MIN_LENGTH_INCREASED("incompatible.request.min.length.increased", true),
+  REQUEST_MIN_LENGTH_INCREASED("incompatible.request.min.length.increased", false),
   REQUEST_NUMERIC_RANGE_DECREASED("incompatible.request.numeric.range.decreased", true),
   REQUEST_ONEOF_DECREASED("incompatible.request.oneof.decreased", true),
   REQUEST_PARAM_ALLOWEMPTY_DECREASED("incompatible.request.param.allowempty.decreased", true),
@@ -32,7 +32,7 @@ public enum BackwardIncompatibleProp {
   RESPONSE_HEADER_REQUIRED_INCREASED("incompatible.response.header.required.increased", true),
   RESPONSE_HEADERS_DECREASED("incompatible.response.headers.decreased", true),
   RESPONSE_MAX_LENGTH_INCREASED("incompatible.response.max.length.increased", true),
-  RESPONSE_MIN_LENGTH_INCREASED("incompatible.response.min.length.increased", true),
+  RESPONSE_MIN_LENGTH_INCREASED("incompatible.response.min.length.increased", false),
   RESPONSE_NUMERIC_RANGE_INCREASED("incompatible.response.numeric.range.increased", false),
   RESPONSE_ONEOF_INCREASED("incompatible.response.oneof.increased", true),
   RESPONSE_REQUIRED_DECREASED("incompatible.response.required.decreased", true),

core/src/test/java/org/openapitools/openapidiff/core/backcompat/MinLengthBCTest.java

@@ -1,5 +1,6 @@
 package org.openapitools.openapidiff.core.backcompat;
 
+import static org.openapitools.openapidiff.core.TestUtils.assertSpecChangedButCompatible;
 import static org.openapitools.openapidiff.core.TestUtils.assertSpecIncompatible;
 import static org.openapitools.openapidiff.core.TestUtils.assertSpecUnchanged;
 import static org.openapitools.openapidiff.core.model.BackwardIncompatibleProp.REQUEST_MIN_LENGTH_INCREASED;
@@ -22,9 +23,19 @@ public void requestMinLengthIncreased() {
     assertSpecIncompatible(BASE, "bc_request_minlength_increased.yaml", prop);
   }
 
+  @Test
+  public void requestMinLengthDecreasedButCompatible() {
+    assertSpecChangedButCompatible(BASE, "bc_request_minlength_changed_but_compatible.yaml");
+  }
+
   @Test
   public void responseMinLengthIncreased() {
     BackwardIncompatibleProp prop = RESPONSE_MIN_LENGTH_INCREASED;
     assertSpecIncompatible(BASE, "bc_response_minlength_increased.yaml", prop);
   }
+
+  @Test
+  public void responseMinLengthDecreasedButCompatible() {
+    assertSpecChangedButCompatible(BASE, "bc_response_minlength_changed_but_compatible.yaml");
+  }
 }

core/src/test/resources/bc_request_minlength_changed_but_compatible.yaml

@@ -0,0 +1,30 @@
+openapi: 3.0.0
+info:
+  description: myDesc
+  title: myTitle
+  version: 1.0.0
+paths:
+  /widgets:
+    post:
+      operationId: widgetCreate
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: string
+              minLength: 3
+          application/xml:
+            schema:
+              type: string
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: string
+                minLength: 5
+            application/xml:
+              schema:
+                type: string
+

core/src/test/resources/bc_response_minlength_changed_but_compatible.yaml

@@ -0,0 +1,31 @@
+openapi: 3.0.0
+info:
+  description: myDesc
+  title: myTitle
+  version: 1.0.0
+paths:
+  /widgets:
+    post:
+      operationId: widgetCreate
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: string
+              minLength: 5
+          application/xml:
+            schema:
+              type: string
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: string
+                minLength: 3
+            application/xml:
+              schema:
+                type: string
+                minLength: 3
+