feat: better handling of enum changes based on direction

| Enum Change   | In Request (path/query/body) | In Response (body) | In Both  |
|---------------|------------------------------|--------------------|----------|
| Value Added   | OK                           | Breaking           | Breaking |
| Value Removed | Breaking                     | OK                 | Breaking |

src/Criteo.OpenApi.Comparator.UTest/OpenApiEnumDirectionTests.cs

@@ -0,0 +1,82 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using Criteo.OpenApi.Comparator.Logging;
+using NUnit.Framework;
+
+namespace Criteo.OpenApi.Comparator.UTest;
+
+[TestFixture]
+public class OpenApiEnumDirectionTests
+{
+    [TestCase("path_add", "#/paths/~1order~1{path}/post/parameters/0/schema/enum")]
+    [TestCase("query_add", "#/paths/~1order~1{path}/post/parameters/1/schema/enum")]
+    [TestCase("body_add", "#/paths/~1order~1{path}/post/requestBody/content/application~1json/schema/properties/foo/enum")]
+    public void CompareOAS_ShouldReturn_NonBreakingEnumChange_InRequest(string oasName, string jsonRef)
+    {
+        var differences = CompareSpecifications(oasName);
+        differences.AssertContains(new ExpectedDifference
+        {
+            Rule = ComparisonRules.AddedEnumValue,
+            Severity = Severity.Warning,
+            NewJsonRef = jsonRef
+        }, 1);
+    }
+
+    [TestCase("response_remove", "#/paths/~1order~1{path}/post/responses/200/content/application~1json/schema/properties/bar/enum")]
+    public void CompareOAS_ShouldReturn_NonBreakingEnumChange_InResponse(string oasName, string jsonRef)
+    {
+        var differences = CompareSpecifications(oasName);
+        differences.AssertContains(new ExpectedDifference
+        {
+            Rule = ComparisonRules.RemovedEnumValue,
+            Severity = Severity.Warning,
+            NewJsonRef = jsonRef
+        }, 1);
+    }
+
+    [TestCase("path_remove", "#/paths/~1order~1{path}/post/parameters/0/schema/enum")]
+    [TestCase("query_remove", "#/paths/~1order~1{path}/post/parameters/1/schema/enum")]
+    [TestCase("body_remove", "#/paths/~1order~1{path}/post/requestBody/content/application~1json/schema/properties/foo/enum")]
+    public void CompareOAS_ShouldReturn_BreakingEnumChange_InRequest(string oasName, string jsonRef)
+    {
+        var differences = CompareSpecifications(oasName);
+        differences.AssertContains(new ExpectedDifference
+        {
+            Rule = ComparisonRules.RemovedEnumValue,
+            Severity = Severity.Error,
+            NewJsonRef = jsonRef,
+        }, 1);
+    }
+
+    [TestCase("response_add", "#/paths/~1order~1{path}/post/responses/200/content/application~1json/schema/properties/bar/enum")]
+    public void CompareOAS_ShouldReturn_BreakingEnumChange_InResponse(string oasName, string jsonRef)
+    {
+        var differences = CompareSpecifications(oasName);
+        differences.AssertContains(new ExpectedDifference
+        {
+            Rule = ComparisonRules.AddedEnumValue,
+            Severity = Severity.Error,
+            NewJsonRef = jsonRef
+        }, 1);
+    }
+
+    private static IList<ComparisonMessage> CompareSpecifications(string oasName)
+    {
+        var baseDirectory = Directory
+            .GetParent(typeof(OpenApiSpecificationsCompareTests).GetTypeInfo().Assembly.Location)
+            .ToString();
+
+        var referenceFileName = Path.Combine(baseDirectory, "Resource", "enum_direction", "reference.json");
+        var newFileName = Path.Combine(baseDirectory, "Resource", "enum_direction", oasName + ".yaml");
+
+        var differences = OpenApiComparator
+            .Compare(File.ReadAllText(referenceFileName), File.ReadAllText(newFileName), strict: true)
+            .ToList();
+
+        OpenApiSpecificationsCompareTests.ValidateDifferences(differences);
+
+        return differences;
+    }
+}

src/Criteo.OpenApi.Comparator.UTest/OpenApiSpecificationsCompareTests.cs

@@ -859,7 +859,7 @@ private static void ValidateMessage(ComparisonMessage message)
             }
         }
 
-        private static void ValidateDifferences(IEnumerable<ComparisonMessage> differences)
+        internal static void ValidateDifferences(IEnumerable<ComparisonMessage> differences)
         {
             foreach (var message in differences)
             {

src/Criteo.OpenApi.Comparator.UTest/Resource/enum_direction/body_add.yaml

@@ -0,0 +1,68 @@
+openapi: 3.0.0
+info:
+  title: My API
+  version: 0.2.0
+paths:
+  /order/{path}:
+    post:
+      summary: New Order
+      operationId: new_order_order__path__post
+      parameters:
+        - name: path
+          in: path
+          required: true
+          schema:
+            enum:
+              - abc
+              - def
+            type: string
+            title: Path
+        - name: query
+          in: query
+          required: true
+          schema:
+            enum:
+              - ghi
+              - jkl
+            type: string
+            title: Query
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/RequestModel"
+      responses:
+        "200":
+          description: Successful Response
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ResponseModel"
+components:
+  schemas:
+    RequestModel:
+      properties:
+        foo:
+          type: string
+          enum:
+            - 123
+            - mno
+            - pqr
+          title: Foo
+      type: object
+      required:
+        - foo
+      title: RequestModel
+    ResponseModel:
+      properties:
+        bar:
+          type: string
+          enum:
+            - stu
+            - vwx
+          title: Bar
+      type: object
+      required:
+        - bar
+      title: ResponseModel

src/Criteo.OpenApi.Comparator.UTest/Resource/enum_direction/body_remove.yaml

@@ -0,0 +1,66 @@
+openapi: 3.0.0
+info:
+  title: My API
+  version: 0.2.0
+paths:
+  /order/{path}:
+    post:
+      summary: New Order
+      operationId: new_order_order__path__post
+      parameters:
+        - name: path
+          in: path
+          required: true
+          schema:
+            enum:
+              - abc
+              - def
+            type: string
+            title: Path
+        - name: query
+          in: query
+          required: true
+          schema:
+            enum:
+              - ghi
+              - jkl
+            type: string
+            title: Query
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/RequestModel"
+      responses:
+        "200":
+          description: Successful Response
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ResponseModel"
+components:
+  schemas:
+    RequestModel:
+      properties:
+        foo:
+          type: string
+          enum:
+            - pqr
+          title: Foo
+      type: object
+      required:
+        - foo
+      title: RequestModel
+    ResponseModel:
+      properties:
+        bar:
+          type: string
+          enum:
+            - stu
+            - vwx
+          title: Bar
+      type: object
+      required:
+        - bar
+      title: ResponseModel

src/Criteo.OpenApi.Comparator.UTest/Resource/enum_direction/path_add.yaml

@@ -0,0 +1,68 @@
+openapi: 3.0.0
+info:
+  title: My API
+  version: 0.2.0
+paths:
+  /order/{path}:
+    post:
+      summary: New Order
+      operationId: new_order_order__path__post
+      parameters:
+        - name: path
+          in: path
+          required: true
+          schema:
+            enum:
+              - abc
+              - 123
+              - def
+            type: string
+            title: Path
+        - name: query
+          in: query
+          required: true
+          schema:
+            enum:
+              - ghi
+              - jkl
+            type: string
+            title: Query
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/RequestModel"
+      responses:
+        "200":
+          description: Successful Response
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ResponseModel"
+components:
+  schemas:
+    RequestModel:
+      properties:
+        foo:
+          type: string
+          enum:
+            - mno
+            - pqr
+          title: Foo
+      type: object
+      required:
+        - foo
+      title: RequestModel
+    ResponseModel:
+      properties:
+        bar:
+          type: string
+          enum:
+            - stu
+            - vwx
+          title: Bar
+      type: object
+      required:
+        - bar
+      title: ResponseModel

src/Criteo.OpenApi.Comparator.UTest/Resource/enum_direction/path_remove.yaml

@@ -0,0 +1,66 @@
+openapi: 3.0.0
+info:
+  title: My API
+  version: 0.2.0
+paths:
+  /order/{path}:
+    post:
+      summary: New Order
+      operationId: new_order_order__path__post
+      parameters:
+        - name: path
+          in: path
+          required: true
+          schema:
+            enum:
+              - abc
+            type: string
+            title: Path
+        - name: query
+          in: query
+          required: true
+          schema:
+            enum:
+              - ghi
+              - jkl
+            type: string
+            title: Query
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/RequestModel"
+      responses:
+        "200":
+          description: Successful Response
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ResponseModel"
+components:
+  schemas:
+    RequestModel:
+      properties:
+        foo:
+          type: string
+          enum:
+            - mno
+            - pqr
+          title: Foo
+      type: object
+      required:
+        - foo
+      title: RequestModel
+    ResponseModel:
+      properties:
+        bar:
+          type: string
+          enum:
+            - stu
+            - vwx
+          title: Bar
+      type: object
+      required:
+        - bar
+      title: ResponseModel