Add support for multiple content types on one content encoding object

.github/workflows/codecov.yml

@@ -8,7 +8,7 @@ jobs:
       image: swift:5.8
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - run: swift test --enable-test-discovery --enable-code-coverage
     - id: analysis
       uses: mattpolzin/[email protected]

.github/workflows/documentation.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         # TODO: replace the documentation generator with something that is still maintained.
 
 #      - name: Generate Documentation

.github/workflows/tests.yml

@@ -13,23 +13,15 @@ jobs:
       fail-fast: false
       matrix:
         image:
-          - swift:5.1-xenial
-          - swift:5.1-bionic
-          - swift:5.2-xenial
-          - swift:5.2-bionic
           - swift:5.2-focal
           - swift:5.2-centos8
-          - swift:5.2-amazonlinux2
-          - swift:5.3-xenial
-          - swift:5.3-bionic
           - swift:5.3-focal
           - swift:5.3-centos8
-          - swift:5.3-amazonlinux2
           # see below for 5.4, 5.5, etc.
     container: ${{ matrix.image }}
     steps:
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Run tests
       run: swift test --enable-test-discovery
   # 5.4 is separate because there was a bug in the compiler that caused
@@ -40,15 +32,12 @@ jobs:
       fail-fast: false
       matrix:
         image:
-          - swift:5.4-xenial
-          - swift:5.4-bionic
           - swift:5.4-focal
           - swift:5.4-centos8
-          - swift:5.4-amazonlinux2
     container: ${{ matrix.image }}
     steps:
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Run tests (without test discovery flag)
       run: swift test -Xswiftc -Xfrontend -Xswiftc -sil-verify-none
   linux-5_5-plus:
@@ -57,36 +46,23 @@ jobs:
       fail-fast: false
       matrix:
         image:
-          - swift:5.5-xenial
-          - swift:5.5-bionic
           - swift:5.5-focal
           - swift:5.5-centos8
-          - swift:5.5-amazonlinux2
-          - swift:5.6-bionic
           - swift:5.6-focal
-          - swift:5.6-amazonlinux2
-          - swift:5.7-bionic
           - swift:5.7-focal
           - swift:5.7-jammy
-          - swift:5.7-amazonlinux2
-          - swift:5.8-bionic
           - swift:5.8-focal
           - swift:5.8-jammy
-          - swift:5.8-amazonlinux2
           - swift:5.9-focal
           - swift:5.9-jammy
-          - swift:5.9-amazonlinux2
           - swift:5.10-focal
           - swift:5.10-jammy
-          - swift:5.10-amazonlinux2
-          - swiftlang/swift:nightly-bionic
           - swiftlang/swift:nightly-focal
           - swiftlang/swift:nightly-jammy
-          - swiftlang/swift:nightly-amazonlinux2
     container: ${{ matrix.image }}
     steps:
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Run tests
       run: swift test
   osx:
@@ -97,6 +73,6 @@ jobs:
         with:
           xcode-version: latest
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run tests
         run: swift test --enable-test-discovery

Sources/OpenAPIKit/Content/ContentEncoding.swift

@@ -14,33 +14,54 @@ extension OpenAPI.Content {
     public struct Encoding: Equatable {
         public typealias Style = OpenAPI.Parameter.SchemaContext.Style
 
-        public let contentType: OpenAPI.ContentType?
+        /// If an encoding object only contains 1 content type, it will be populated here.
+        /// Two or more content types will result in a null value here but the `contentTypes`
+        /// (plural) property will contain all content types specified.
+        ///
+        /// The singular `contentType` property is only provided for backwards compatibility and
+        /// using the plural `contentTypes` property should be preferred.
+        @available(*, deprecated, message: "use contentTypes instead")
+        public var contentType: OpenAPI.ContentType? {
+            guard let contentType = contentTypes.first,
+                  contentTypes.count == 1 else {
+                return nil
+            }
+            return contentType
+        }
+
+        public let contentTypes: [OpenAPI.ContentType]
         public let headers: OpenAPI.Header.Map?
         public let style: Style
         public let explode: Bool
         public let allowReserved: Bool
 
+        /// The singular `contentType` argument is only provided for backwards compatibility and
+        /// using the plural `contentTypes` argument should be preferred.
         public init(
             contentType: OpenAPI.ContentType? = nil,
+            contentTypes: [OpenAPI.ContentType] = [],
             headers: OpenAPI.Header.Map? = nil,
             style: Style = Self.defaultStyle,
             allowReserved: Bool = false
         ) {
-            self.contentType = contentType
+            self.contentTypes = contentTypes + [contentType].compactMap { $0 }
             self.headers = headers
             self.style = style
             self.explode = style.defaultExplode
             self.allowReserved = allowReserved
         }
 
+        /// The singular `contentType` argument is only provided for backwards compatibility and
+        /// using the plural `contentTypes` argument should be preferred.
         public init(
             contentType: OpenAPI.ContentType? = nil,
+            contentTypes: [OpenAPI.ContentType] = [],
             headers: OpenAPI.Header.Map? = nil,
             style: Style = Self.defaultStyle,
             explode: Bool,
             allowReserved: Bool = false
         ) {
-            self.contentType = contentType
+            self.contentTypes = contentTypes + [contentType].compactMap { $0 }
             self.headers = headers
             self.style = style
             self.explode = explode
@@ -56,7 +77,12 @@ extension OpenAPI.Content.Encoding: Encodable {
     public func encode(to encoder: Encoder) throws {
         var container = encoder.container(keyedBy: CodingKeys.self)
 
-        try container.encodeIfPresent(contentType, forKey: .contentType)
+        if contentTypes.count > 0 {
+            let contentTypesString = contentTypes
+                .map(\.rawValue)
+                .joined(separator: ", ")
+            try container.encode(contentTypesString, forKey: .contentType)
+        }
         try container.encodeIfPresent(headers, forKey: .headers)
 
         if style != Self.defaultStyle {
@@ -77,7 +103,16 @@ extension OpenAPI.Content.Encoding: Decodable {
     public init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
 
-        contentType = try container.decodeIfPresent(OpenAPI.ContentType.self, forKey: .contentType)
+        let contentTypesString = try container.decodeIfPresent(String.self, forKey: .contentType)
+        if let contentTypesString = contentTypesString {
+            contentTypes = contentTypesString
+                .split(separator: ",")
+                .compactMap { string in
+                    OpenAPI.ContentType.init(rawValue: string.trimmingCharacters(in: .whitespaces))
+                }
+        } else {
+            contentTypes = []
+        }
 
         headers = try container.decodeIfPresent(OpenAPI.Header.Map.self, forKey: .headers)
 

Tests/OpenAPIKitTests/Content/ContentTests.swift

@@ -570,6 +570,33 @@ extension ContentTests {
         XCTAssertEqual(encoding, OpenAPI.Content.Encoding(contentType: .csv))
     }
 
+    func test_encoding_multiple_contentTypes_encode() throws {
+        let encoding = OpenAPI.Content.Encoding(contentTypes: [.csv, .json])
+
+        let encodedEncoding = try! orderUnstableTestStringFromEncoding(of: encoding)
+
+        assertJSONEquivalent(
+            encodedEncoding,
+            """
+            {
+              "contentType" : "text\\/csv, application\\/json"
+            }
+            """
+        )
+    }
+
+    func test_encoding_multiple_contentTypes_decode() throws {
+        let encodingData =
+        """
+        {
+            "contentType": "text/csv, application/json"
+        }
+        """.data(using: .utf8)!
+        let encoding = try! orderUnstableDecode(OpenAPI.Content.Encoding.self, from: encodingData)
+
+        XCTAssertEqual(encoding, OpenAPI.Content.Encoding(contentTypes: [.csv, .json]))
+    }
+
     func test_encoding_headers_encode() throws {
         let encoding = OpenAPI.Content.Encoding(headers: [
             "X-CustomThing": .init(OpenAPI.Header(schema: .string))