Fix unexpected collection format during V2 serialization

src/Microsoft.OpenApi/Models/OpenApiParameter.cs

@@ -377,7 +377,7 @@ public void SerializeAsV2WithoutReference(IOpenApiWriter writer)
                 // allowEmptyValue
                 writer.WriteProperty(OpenApiConstants.AllowEmptyValue, AllowEmptyValue, false);
 
-                if (this.In == ParameterLocation.Query)
+                if (this.In == ParameterLocation.Query && Schema?.Type == "array")
                 {
                     if (this.Style == ParameterStyle.Form && this.Explode == true)
                     {

test/Microsoft.OpenApi.Tests/Models/OpenApiDocumentTests.SerializeAdvancedDocumentAsV2JsonWorks_produceTerseOutput=False.verified.txt

@@ -46,8 +46,7 @@
             "name": "limit",
             "description": "maximum number of results to return",
             "type": "integer",
-            "format": "int32",
-            "collectionFormat": "multi"
+            "format": "int32"
           }
         ],
         "responses": {

test/Microsoft.OpenApi.Tests/Models/OpenApiDocumentTests.SerializeAdvancedDocumentAsV2JsonWorks_produceTerseOutput=True.verified.txt

@@ -1 +1 @@
-{"swagger":"2.0","info":{"title":"Swagger Petstore (Simple)","description":"A sample API that uses a petstore as an example to demonstrate features in the swagger-2.0 specification","termsOfService":"http://helloreverb.com/terms/","contact":{"name":"Swagger API team","url":"http://swagger.io","email":"[email protected]"},"license":{"name":"MIT","url":"http://opensource.org/licenses/MIT"},"version":"1.0.0"},"host":"petstore.swagger.io","basePath":"/api","schemes":["http"],"paths":{"/pets":{"get":{"description":"Returns all pets from the system that the user has access to","operationId":"findPets","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"query","name":"tags","description":"tags to filter by","type":"array","items":{"type":"string"},"collectionFormat":"multi"},{"in":"query","name":"limit","description":"maximum number of results to return","type":"integer","format":"int32","collectionFormat":"multi"}],"responses":{"200":{"description":"pet response","schema":{"type":"array","items":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}}},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}},"post":{"description":"Creates a new pet in the store.  Duplicates are allowed","operationId":"addPet","consumes":["application/json"],"produces":["application/json","text/html"],"parameters":[{"in":"body","name":"body","description":"Pet to add to the store","required":true,"schema":{"required":["name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}}],"responses":{"200":{"description":"pet response","schema":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}}},"/pets/{id}":{"get":{"description":"Returns a user based on a single ID, if the user does not have access to the pet","operationId":"findPetById","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to fetch","required":true,"type":"integer","format":"int64"}],"responses":{"200":{"description":"pet response","schema":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}},"delete":{"description":"deletes a single pet based on the ID supplied","operationId":"deletePet","produces":["text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to delete","required":true,"type":"integer","format":"int64"}],"responses":{"204":{"description":"pet deleted"},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}}}},"definitions":{"pet":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"newPet":{"required":["name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"errorModel":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}
+{"swagger":"2.0","info":{"title":"Swagger Petstore (Simple)","description":"A sample API that uses a petstore as an example to demonstrate features in the swagger-2.0 specification","termsOfService":"http://helloreverb.com/terms/","contact":{"name":"Swagger API team","url":"http://swagger.io","email":"[email protected]"},"license":{"name":"MIT","url":"http://opensource.org/licenses/MIT"},"version":"1.0.0"},"host":"petstore.swagger.io","basePath":"/api","schemes":["http"],"paths":{"/pets":{"get":{"description":"Returns all pets from the system that the user has access to","operationId":"findPets","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"query","name":"tags","description":"tags to filter by","type":"array","items":{"type":"string"},"collectionFormat":"multi"},{"in":"query","name":"limit","description":"maximum number of results to return","type":"integer","format":"int32"}],"responses":{"200":{"description":"pet response","schema":{"type":"array","items":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}}},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}},"post":{"description":"Creates a new pet in the store.  Duplicates are allowed","operationId":"addPet","consumes":["application/json"],"produces":["application/json","text/html"],"parameters":[{"in":"body","name":"body","description":"Pet to add to the store","required":true,"schema":{"required":["name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}}],"responses":{"200":{"description":"pet response","schema":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}}},"/pets/{id}":{"get":{"description":"Returns a user based on a single ID, if the user does not have access to the pet","operationId":"findPetById","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to fetch","required":true,"type":"integer","format":"int64"}],"responses":{"200":{"description":"pet response","schema":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}}},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}},"delete":{"description":"deletes a single pet based on the ID supplied","operationId":"deletePet","produces":["text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to delete","required":true,"type":"integer","format":"int64"}],"responses":{"204":{"description":"pet deleted"},"4XX":{"description":"unexpected client error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}},"5XX":{"description":"unexpected server error","schema":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}}}},"definitions":{"pet":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"newPet":{"required":["name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"errorModel":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}

test/Microsoft.OpenApi.Tests/Models/OpenApiDocumentTests.SerializeAdvancedDocumentWithReferenceAsV2JsonWorks_produceTerseOutput=False.verified.txt

@@ -46,8 +46,7 @@
             "name": "limit",
             "description": "maximum number of results to return",
             "type": "integer",
-            "format": "int32",
-            "collectionFormat": "multi"
+            "format": "int32"
           }
         ],
         "responses": {

test/Microsoft.OpenApi.Tests/Models/OpenApiDocumentTests.SerializeAdvancedDocumentWithReferenceAsV2JsonWorks_produceTerseOutput=True.verified.txt

@@ -1 +1 @@
-{"swagger":"2.0","info":{"title":"Swagger Petstore (Simple)","description":"A sample API that uses a petstore as an example to demonstrate features in the swagger-2.0 specification","termsOfService":"http://helloreverb.com/terms/","contact":{"name":"Swagger API team","url":"http://swagger.io","email":"[email protected]"},"license":{"name":"MIT","url":"http://opensource.org/licenses/MIT"},"version":"1.0.0"},"host":"petstore.swagger.io","basePath":"/api","schemes":["http"],"paths":{"/pets":{"get":{"description":"Returns all pets from the system that the user has access to","operationId":"findPets","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"query","name":"tags","description":"tags to filter by","type":"array","items":{"type":"string"},"collectionFormat":"multi"},{"in":"query","name":"limit","description":"maximum number of results to return","type":"integer","format":"int32","collectionFormat":"multi"}],"responses":{"200":{"description":"pet response","schema":{"type":"array","items":{"$ref":"#/definitions/pet"}}},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}},"post":{"description":"Creates a new pet in the store.  Duplicates are allowed","operationId":"addPet","consumes":["application/json"],"produces":["application/json","text/html"],"parameters":[{"in":"body","name":"body","description":"Pet to add to the store","required":true,"schema":{"$ref":"#/definitions/newPet"}}],"responses":{"200":{"description":"pet response","schema":{"$ref":"#/definitions/pet"}},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}}},"/pets/{id}":{"get":{"description":"Returns a user based on a single ID, if the user does not have access to the pet","operationId":"findPetById","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to fetch","required":true,"type":"integer","format":"int64"}],"responses":{"200":{"description":"pet response","schema":{"$ref":"#/definitions/pet"}},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}},"delete":{"description":"deletes a single pet based on the ID supplied","operationId":"deletePet","produces":["text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to delete","required":true,"type":"integer","format":"int64"}],"responses":{"204":{"description":"pet deleted"},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}}}},"definitions":{"pet":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"newPet":{"required":["name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"errorModel":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}
+{"swagger":"2.0","info":{"title":"Swagger Petstore (Simple)","description":"A sample API that uses a petstore as an example to demonstrate features in the swagger-2.0 specification","termsOfService":"http://helloreverb.com/terms/","contact":{"name":"Swagger API team","url":"http://swagger.io","email":"[email protected]"},"license":{"name":"MIT","url":"http://opensource.org/licenses/MIT"},"version":"1.0.0"},"host":"petstore.swagger.io","basePath":"/api","schemes":["http"],"paths":{"/pets":{"get":{"description":"Returns all pets from the system that the user has access to","operationId":"findPets","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"query","name":"tags","description":"tags to filter by","type":"array","items":{"type":"string"},"collectionFormat":"multi"},{"in":"query","name":"limit","description":"maximum number of results to return","type":"integer","format":"int32"}],"responses":{"200":{"description":"pet response","schema":{"type":"array","items":{"$ref":"#/definitions/pet"}}},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}},"post":{"description":"Creates a new pet in the store.  Duplicates are allowed","operationId":"addPet","consumes":["application/json"],"produces":["application/json","text/html"],"parameters":[{"in":"body","name":"body","description":"Pet to add to the store","required":true,"schema":{"$ref":"#/definitions/newPet"}}],"responses":{"200":{"description":"pet response","schema":{"$ref":"#/definitions/pet"}},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}}},"/pets/{id}":{"get":{"description":"Returns a user based on a single ID, if the user does not have access to the pet","operationId":"findPetById","produces":["application/json","application/xml","text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to fetch","required":true,"type":"integer","format":"int64"}],"responses":{"200":{"description":"pet response","schema":{"$ref":"#/definitions/pet"}},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}},"delete":{"description":"deletes a single pet based on the ID supplied","operationId":"deletePet","produces":["text/html"],"parameters":[{"in":"path","name":"id","description":"ID of pet to delete","required":true,"type":"integer","format":"int64"}],"responses":{"204":{"description":"pet deleted"},"4XX":{"description":"unexpected client error","schema":{"$ref":"#/definitions/errorModel"}},"5XX":{"description":"unexpected server error","schema":{"$ref":"#/definitions/errorModel"}}}}}},"definitions":{"pet":{"required":["id","name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"newPet":{"required":["name"],"type":"object","properties":{"id":{"format":"int64","type":"integer"},"name":{"type":"string"},"tag":{"type":"string"}}},"errorModel":{"required":["code","message"],"type":"object","properties":{"code":{"format":"int32","type":"integer"},"message":{"type":"string"}}}}}

test/Microsoft.OpenApi.Tests/Models/OpenApiDocumentTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
 using System;
@@ -1356,5 +1356,57 @@ public void CopyConstructorForAdvancedDocumentWorks()
             Assert.Equal(2, doc.Paths.Count);
             Assert.NotNull(doc.Components);
         }
+
+        [Fact]
+        public void SerializeV2DocumentWithNonArraySchemaTypeDoesNotWriteOutCollectionFormat()
+        {
+            // Arrange
+            var expected = @"swagger: '2.0'
+info: { }
+paths:
+  /foo:
+    get:
+      parameters:
+        - in: query
+          type: string
+      responses: { }";
+
+            var doc = new OpenApiDocument
+            {
+                Info = new OpenApiInfo(),
+                Paths = new OpenApiPaths
+                {                    
+                    ["/foo"] = new OpenApiPathItem
+                    {
+                        Operations = new Dictionary<OperationType, OpenApiOperation> 
+                        {
+                            [OperationType.Get] = new OpenApiOperation
+                            {
+                                Parameters = new List<OpenApiParameter>
+                                {
+                                    new OpenApiParameter
+                                    {
+                                        In = ParameterLocation.Query,
+                                        Schema = new OpenApiSchema
+                                        {
+                                            Type = "string"
+                                        }
+                                    }
+                                },
+                                Responses = new OpenApiResponses()
+                            }
+                        }
+                    }
+                }
+            };
+
+            // Act
+            var actual = doc.SerializeAsYaml(OpenApiSpecVersion.OpenApi2_0);
+
+            // Assert
+            actual = actual.MakeLineBreaksEnvironmentNeutral();
+            expected = expected.MakeLineBreaksEnvironmentNeutral();
+            actual.Should().Be(expected);
+        }
     }
 }