Add test to validate

Author: MaggieKimani1

test/Microsoft.OpenApi.Readers.Tests/V31Tests/OpenApiDocumentTests.cs

@@ -481,5 +481,21 @@ public void ParseDocumentWithPatternPropertiesInSchemaWorks()
             actualSchema.Should().BeEquivalentTo(expectedSchema);
             actualMediaType.MakeLineBreaksEnvironmentNeutral().Should().BeEquivalentTo(expectedMediaType.MakeLineBreaksEnvironmentNeutral());
         }
+
+        [Fact]
+        public void ParseDocumentWithReferenceByIdGetsResolved()
+        {
+            // Arrange and Act
+            var result = OpenApiDocument.Load(Path.Combine(SampleFolderPath, "docWithReferenceById.yaml"));
+
+            var responseSchema = result.OpenApiDocument.Paths["/resource"].Operations[OperationType.Get].Responses["200"].Content["application/json"].Schema;
+            var requestBodySchema = result.OpenApiDocument.Paths["/resource"].Operations[OperationType.Post].RequestBody.Content["application/json"].Schema;
+            var parameterSchema = result.OpenApiDocument.Paths["/resource"].Operations[OperationType.Get].Parameters[0].Schema;
+
+            // Assert
+            Assert.Equal("object", responseSchema.Type);
+            Assert.Equal("object", requestBodySchema.Type);
+            Assert.Equal("string", parameterSchema.Type);
+        }
     }
 }

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiDocument/docWithReferenceById.yaml

@@ -0,0 +1,45 @@
+openapi: 3.1.0
+info:
+  title: ReferenceById
+  version: 1.0.0
+paths:
+  /resource:
+    get:
+      parameters:
+        - name: id
+          in: query
+          required: true
+          schema:
+            $ref: 'https://example.com/schemas/id.json'
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: 'https://example.com/schemas/resource.json'
+    post:
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: 'https://example.com/schemas/resource.json'
+      responses:
+        '200':
+          description: OK
+components:
+  schemas:
+    Resource:
+      $id: 'https://example.com/schemas/resource.json'
+      type: object
+      properties:
+        id:
+          type: string
+        name:
+          type: string
+        reference:
+          $ref: '#/components/schemas/Resource'
+    Id:
+      $id: 'https://example.com/schemas/id.json'
+      type: string