Provide NIOAsyncTestingChannel #2238
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Lukasa
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cc @0xTim, this should help with the WebSocket concerns you had. |
Motivation Testing versions of NIO code that involve interfacing with Swift Concurrency is currently a difficult business. In particular, EmbeddedChannel is not available in Swift concurrency, making it difficult to write tests where you fully control the I/O. To that end, we should provide a variation of EmbeddedChannel that makes testing these things possible. Modifications Provide an implementation of NIOAsyncTestingChannel. Results Users can write tests confidently with async/await.
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Great once this is merged I'll try and get my Websocket PR working |
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| /// `WrongTypeError` is throws if you use `readInbound` or `readOutbound` and request a certain type but the first |
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| /// `WrongTypeError` is throws if you use `readInbound` or `readOutbound` and request a certain type but the first | |
| /// `WrongTypeError` is thrown if you use `readInbound` or `readOutbound` and request a certain type but the first |
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| /// Returns the `NIOAsyncTestingEventLoop` that this `NIOAsyncTestingChannel` uses. This will return the same instance as | ||
| /// `NIOAsyncTestingChannel.eventLoop` but as the concrete `NIOAsyncTestingEventLoop` rather than as `EventLoop` existential. | ||
| public let embeddedEventLoop: NIOAsyncTestingEventLoop |
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Should this be testingEventLoop?
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| /// The `NIOAsyncTestingChannel` has inbound, outbound, or pending outbound data left on `finish`. | ||
| case leftOvers(inbound: CircularBuffer<NIOAny>, outbound: CircularBuffer<NIOAny>, pendingOutbound: [NIOAny]) |
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Do we want to continue using CircularBuffer in new public API or should we start switching to Deque where possible?
(I know these come from the channel core and we probably don't want to incur the additional allocation cost from copying them over but I'm still interested in the answer to the general case)
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Yeah that's a good question. In this instance we should leave it due to the existing use in the embedded channel, but I think that we should be using Deque in new API if we don't have a good reason not to.
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Hmm, we've regressed allocations in |
| import NIOConcurrencyHelpers | ||
| import NIOCore | ||
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| /// `NIOAsyncTestingChannel` is a `Channel` implementation that does no |
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Should we use DocC syntax in all the comments here, i.e. double backticks `` and reference all the types fully?
| /// are no elements in the outbound buffer, `nil` will be returned. | ||
| /// | ||
| /// Data hits the `NIOAsyncTestingChannel`'s outbound buffer when data was written using `write`, then `flush`ed, and | ||
| /// then travelled the `ChannelPipeline` all the way too the front. For data to hit the outbound buffer, the very |
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| /// then travelled the `ChannelPipeline` all the way too the front. For data to hit the outbound buffer, the very | |
| /// then travelled the `ChannelPipeline` all the way to the front. For data to hit the outbound buffer, the very |
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| /// This method will throw the error that is stored in the `NIOAsyncTestingChannel` if any. | ||
| /// | ||
| /// The `NIOAsyncTestingChannel` will store an error if some error travels the `ChannelPipeline` all the way past its end. |
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Can we specify what end of the pipeline?
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Errors can only go to one end of the pipeline.
| /// | ||
| /// - parameters: | ||
| /// - loop: The `NIOAsyncTestingEventLoop` to use. | ||
| public init(loop: NIOAsyncTestingEventLoop = NIOAsyncTestingEventLoop()) { |
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NIT: Could we move all the inits above the methods?
Motivation
Testing versions of NIO code that involve interfacing with Swift
Concurrency is currently a difficult business. In particular,
EmbeddedChannel is not available in Swift concurrency, making it
difficult to write tests where you fully control the I/O.
To that end, we should provide a variation of EmbeddedChannel that makes
testing these things possible.
Modifications
Provide an implementation of NIOAsyncTestingChannel.
Results
Users can write tests confidently with async/await.