use B2MD verifier (#52)

Motivation:

Use B2MDVerifier for the B2MDs in NIOExtras. Already found one bug,
separetely fixed in #51.

Modifications:

Write a basic validation test for all B2MDs.

Result:

Better test coverage.

Package.swift

@@ -25,7 +25,7 @@ var targets: [PackageDescription.Target] = [
             linkerSettings: [
                 .linkedLibrary("z")
             ]),
-    .testTarget(name: "NIOExtrasTests", dependencies: ["NIOExtras"]),
+    .testTarget(name: "NIOExtrasTests", dependencies: ["NIOExtras", "NIOTestUtils"]),
     .testTarget(name: "NIOHTTPCompressionTests", dependencies: ["NIOHTTPCompression"]),
 ]
 
@@ -38,7 +38,7 @@ let package = Package(
         .library(name: "NIOHTTPCompression", targets: ["NIOHTTPCompression"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-nio.git", from: "2.0.0"),
+        .package(url: "https://github.com/apple/swift-nio.git", from: "2.2.0"),
     ],
     targets: targets
 )

Sources/NIOExtras/LengthFieldBasedFrameDecoder.swift

@@ -43,8 +43,7 @@ public final class LengthFieldBasedFrameDecoder: ByteToMessageDecoder {
         case four
         case eight
         
-        fileprivate var length: Int {
-            
+        var length: Int {
             switch self {
             case .one:
                 return 1

Tests/NIOExtrasTests/FixedLengthFrameDecoderTest+XCTest.swift

@@ -30,7 +30,7 @@ extension FixedLengthFrameDecoderTest {
                 ("testDecodeIfMoreBytesAreSent", testDecodeIfMoreBytesAreSent),
                 ("testRemoveHandlerWhenBufferIsNotEmpty", testRemoveHandlerWhenBufferIsNotEmpty),
                 ("testRemoveHandlerWhenBufferIsEmpty", testRemoveHandlerWhenBufferIsEmpty),
-                ("testCloseInChannelRead", testCloseInChannelRead),
+                ("testBasicValidation", testBasicValidation),
            ]
    }
 }

Tests/NIOExtrasTests/FixedLengthFrameDecoderTest.swift

@@ -15,6 +15,7 @@
 import XCTest
 import NIO
 import NIOExtras
+import NIOTestUtils
 
 class FixedLengthFrameDecoderTest: XCTestCase {
     public func testDecodeIfFewerBytesAreSent() throws {
@@ -115,30 +116,22 @@ class FixedLengthFrameDecoderTest: XCTestCase {
         XCTAssertTrue(try channel.finish().isClean)
     }
 
-    func testCloseInChannelRead() {
-        let channel = EmbeddedChannel(handler: ByteToMessageHandler(LengthFieldBasedFrameDecoder(lengthFieldLength: .four)))
-        class CloseInReadHandler: ChannelInboundHandler {
-            typealias InboundIn = ByteBuffer
-
-            private var numberOfReads = 0
-
-            func channelRead(context: ChannelHandlerContext, data: NIOAny) {
-                self.numberOfReads += 1
-                XCTAssertEqual(1, self.numberOfReads)
-                XCTAssertEqual([UInt8(100)], Array(self.unwrapInboundIn(data).readableBytesView))
-                context.close().whenFailure { error in
-                    XCTFail("unexpected error: \(error)")
-                }
-                context.fireChannelRead(data)
+    func testBasicValidation() {
+        for length in 1 ... 20 {
+            let inputs = [
+                String(decoding: Array(repeating: UInt8(ascii: "a"), count: length), as: Unicode.UTF8.self),
+                String(decoding: Array(repeating: UInt8(ascii: "b"), count: length), as: Unicode.UTF8.self),
+                String(decoding: Array(repeating: UInt8(ascii: "c"), count: length), as: Unicode.UTF8.self),
+            ]
+            func byteBuffer(_ string: String) -> ByteBuffer {
+                var buffer = ByteBufferAllocator().buffer(capacity: string.utf8.count)
+                buffer.writeString(string)
+                return buffer
             }
+            let inputOutputPairs: [(String, [ByteBuffer])] = inputs.map { ($0, [byteBuffer($0)]) }
+            XCTAssertNoThrow(try ByteToMessageDecoderVerifier.verifyDecoder(stringInputOutputPairs: inputOutputPairs) {
+                FixedLengthFrameDecoder(frameLength: length)
+            })
         }
-        XCTAssertNoThrow(try channel.pipeline.addHandler(CloseInReadHandler()).wait())
-
-        var buf = channel.allocator.buffer(capacity: 1024)
-        buf.writeBytes([UInt8(0), 0, 0, 1, 100])
-        XCTAssertNoThrow(try channel.writeInbound(buf))
-        XCTAssertNoThrow(XCTAssertEqual([100], Array((try channel.readInbound() as ByteBuffer?)!.readableBytesView)))
-        XCTAssertNoThrow(XCTAssertNil(try channel.readInbound()))
-
     }
 }

Tests/NIOExtrasTests/LengthFieldBasedFrameDecoderTest+XCTest.swift

@@ -40,6 +40,8 @@ extension LengthFieldBasedFrameDecoderTest {
                 ("testDecodeWithUInt16HeaderWithPartialBody", testDecodeWithUInt16HeaderWithPartialBody),
                 ("testRemoveHandlerWhenBufferIsEmpty", testRemoveHandlerWhenBufferIsEmpty),
                 ("testRemoveHandlerWhenBufferIsNotEmpty", testRemoveHandlerWhenBufferIsNotEmpty),
+                ("testCloseInChannelRead", testCloseInChannelRead),
+                ("testBasicVerification", testBasicVerification),
            ]
    }
 }

Tests/NIOExtrasTests/LengthFieldBasedFrameDecoderTest.swift

@@ -14,7 +14,8 @@
 
 import XCTest
 import NIO
-import NIOExtras
+@testable import NIOExtras
+import NIOTestUtils
 
 private let standardDataString = "abcde"
 
@@ -375,4 +376,83 @@ class LengthFieldBasedFrameDecoderTest: XCTestCase {
             }))
         XCTAssertTrue(try self.channel.finish().isClean)
     }
+
+    func testCloseInChannelRead() {
+        let channel = EmbeddedChannel(handler: ByteToMessageHandler(LengthFieldBasedFrameDecoder(lengthFieldLength: .four)))
+        class CloseInReadHandler: ChannelInboundHandler {
+            typealias InboundIn = ByteBuffer
+
+            private var numberOfReads = 0
+
+            func channelRead(context: ChannelHandlerContext, data: NIOAny) {
+                self.numberOfReads += 1
+                XCTAssertEqual(1, self.numberOfReads)
+                XCTAssertEqual([UInt8(100)], Array(self.unwrapInboundIn(data).readableBytesView))
+                context.close().whenFailure { error in
+                    XCTFail("unexpected error: \(error)")
+                }
+                context.fireChannelRead(data)
+            }
+        }
+        XCTAssertNoThrow(try channel.pipeline.addHandler(CloseInReadHandler()).wait())
+
+        var buf = channel.allocator.buffer(capacity: 1024)
+        buf.writeBytes([UInt8(0), 0, 0, 1, 100])
+        XCTAssertNoThrow(try channel.writeInbound(buf))
+        XCTAssertNoThrow(XCTAssertEqual([100], Array((try channel.readInbound() as ByteBuffer?)!.readableBytesView)))
+        XCTAssertNoThrow(XCTAssertNil(try channel.readInbound()))
+    }
+
+    func testBasicVerification() {
+        let inputs: [(LengthFieldBasedFrameDecoder.ByteLength, [(Int, String)])] = [
+            (.one, [
+                (6, "abcdef"),
+                (0, ""),
+                (9, "123456789"),
+                (Int(UInt8.max),
+                 String(decoding: Array(repeating: UInt8(ascii: "X"), count: Int(UInt8.max)), as: Unicode.UTF8.self)),
+                ]),
+            (.two, [
+                (1, "a"),
+                (0, ""),
+                (9, "123456789"),
+                (307,
+                 String(decoding: Array(repeating: UInt8(ascii: "X"), count: 307), as: Unicode.UTF8.self)),
+                ]),
+            (.four, [
+                (1, "a"),
+                (0, ""),
+                (3, "333"),
+                (307,
+                 String(decoding: Array(repeating: UInt8(ascii: "X"), count: 307), as: Unicode.UTF8.self)),
+                ]),
+            (.eight, [
+                (1, "a"),
+                (0, ""),
+                (4, "aaaa"),
+                (307,
+                 String(decoding: Array(repeating: UInt8(ascii: "X"), count: 307), as: Unicode.UTF8.self)),
+                ]),
+        ]
+
+        for input in inputs {
+            let (lenBytes, inputData) = input
+
+            func byteBuffer(length: Int, string: String) -> ByteBuffer {
+                var buf = self.channel.allocator.buffer(capacity: string.utf8.count + 8)
+                buf.writeInteger(length)
+                buf.moveReaderIndex(forwardBy: 8 - lenBytes.length)
+                buf.writeString(string)
+                return buf
+            }
+
+            let inputOutputPairs = inputData.map { (input: (Int, String)) -> (ByteBuffer, [ByteBuffer]) in
+                let bytes = byteBuffer(length: input.0, string: input.1)
+                return (bytes, [bytes.getSlice(at: bytes.readerIndex + lenBytes.length, length: input.0)!])
+            }
+            XCTAssertNoThrow(try ByteToMessageDecoderVerifier.verifyDecoder(inputOutputPairs: inputOutputPairs) {
+                LengthFieldBasedFrameDecoder(lengthFieldLength: lenBytes)
+            })
+        }
+    }
 }

Tests/NIOExtrasTests/LineBasedFrameDecoderTest+XCTest.swift

@@ -34,6 +34,7 @@ extension LineBasedFrameDecoderTest {
                 ("testChannelInactiveWithLeftOverBytes", testChannelInactiveWithLeftOverBytes),
                 ("testMoreDataAvailableWhenChannelBecomesInactive", testMoreDataAvailableWhenChannelBecomesInactive),
                 ("testDripFedCRLN", testDripFedCRLN),
+                ("testBasicValidation", testBasicValidation),
            ]
    }
 }

Tests/NIOExtrasTests/LineBasedFrameDecoderTest.swift

@@ -15,6 +15,7 @@
 import XCTest
 @testable import NIO // to inspect the cumulationBuffer
 import NIOExtras
+import NIOTestUtils
 
 class LineBasedFrameDecoderTest: XCTestCase {
     private var channel: EmbeddedChannel!
@@ -186,4 +187,30 @@ class LineBasedFrameDecoderTest: XCTestCase {
         buffer.writeString("a")
         XCTAssertNoThrow(XCTAssertEqual(buffer, try self.channel.readInbound()))
     }
+
+    func testBasicValidation() {
+        func byteBuffer(_ string: String) -> ByteBuffer {
+            var buffer = self.channel.allocator.buffer(capacity: string.utf8.count)
+            buffer.writeString(string)
+            return buffer
+        }
+
+        do {
+            try ByteToMessageDecoderVerifier.verifyDecoder(stringInputOutputPairs: [
+                ("\n", [byteBuffer("")]),
+                ("\r\n", [byteBuffer("")]),
+                ("a\r\n", [byteBuffer("a")]),
+                ("a\n", [byteBuffer("a")]),
+                ("a\rb\n", [byteBuffer("a\rb")]),
+                ("Content-Length: 17\r\nConnection: close\r\n\r\n", [byteBuffer("Content-Length: 17"),
+                                                                     byteBuffer("Connection: close"),
+                                                                     byteBuffer("")])
+            ]) {
+                return LineBasedFrameDecoder()
+            }
+        } catch {
+            print(error)
+            XCTFail()
+        }
+    }
 }