cloud_sdk_testkit/
mock.rs

1//! Deterministic no-allocation mock transport.
2
3mod local;
4
5pub use local::LocalMockTransport;
6
7use core::fmt;
8use core::sync::atomic::{AtomicUsize, Ordering};
9
10use cloud_sdk::Method;
11use cloud_sdk::authentication::{
12    AsyncAuthenticatedTransport, AuthenticatedRequest, BlockingAuthenticatedTransport,
13};
14use cloud_sdk::transport::{
15    AsyncResponseStaging, AsyncTransport, BlockingTransport, BoundTransport, EndpointIdentity,
16    EndpointIdentityError, HeaderSensitivity, RequestHeaders, RequestTarget, ResponseAttempt,
17    ResponseCompletion, ResponseContentType, ResponseHeaders, ResponseMetadata, ResponseWriter,
18    TransportRequest,
19};
20
21use crate::{FixtureBodyError, ResponseFixture};
22
23/// Expected request fields for one mock exchange.
24#[derive(Clone, Copy)]
25pub struct ExpectedRequest<'a> {
26    method: Method,
27    target: RequestTarget<'a>,
28    body: &'a [u8],
29    headers: RequestHeaders<'a>,
30}
31
32impl<'a> ExpectedRequest<'a> {
33    /// Creates a bodyless expected request.
34    #[must_use]
35    pub const fn new(method: Method, target: RequestTarget<'a>) -> Self {
36        Self {
37            method,
38            target,
39            body: &[],
40            headers: RequestHeaders::EMPTY,
41        }
42    }
43
44    /// Adds the exact expected request body.
45    #[must_use]
46    pub const fn with_body(mut self, body: &'a [u8]) -> Self {
47        self.body = body;
48        self
49    }
50
51    /// Adds the exact expected ordered request headers.
52    #[must_use]
53    pub const fn with_headers(mut self, headers: RequestHeaders<'a>) -> Self {
54        self.headers = headers;
55        self
56    }
57
58    const fn method(self) -> Method {
59        self.method
60    }
61
62    const fn target(self) -> RequestTarget<'a> {
63        self.target
64    }
65
66    const fn body(self) -> &'a [u8] {
67        self.body
68    }
69
70    const fn headers(self) -> RequestHeaders<'a> {
71        self.headers
72    }
73}
74
75impl fmt::Debug for ExpectedRequest<'_> {
76    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
77        formatter
78            .debug_struct("ExpectedRequest")
79            .field("method", &self.method)
80            .field("target", &"[redacted]")
81            .field("body", &"[redacted]")
82            .field("headers", &self.headers)
83            .finish()
84    }
85}
86
87/// One expected request and deterministic response.
88#[derive(Debug)]
89pub struct MockExchange<'a> {
90    request: ExpectedRequest<'a>,
91    response: ResponseFixture<'a>,
92}
93
94impl<'a> MockExchange<'a> {
95    /// Creates one mock exchange.
96    #[must_use]
97    pub const fn new(request: ExpectedRequest<'a>, response: ResponseFixture<'a>) -> Self {
98        Self { request, response }
99    }
100}
101
102/// Deterministic mock transport failure.
103#[derive(Clone, Copy, Debug, Eq, PartialEq)]
104pub enum MockError {
105    /// No expected exchange remains.
106    Exhausted,
107    /// HTTP method differs from the next expectation.
108    MethodMismatch,
109    /// Request target differs from the next expectation.
110    TargetMismatch,
111    /// Request body differs from the next expectation.
112    BodyMismatch,
113    /// Request headers differ from the next expectation.
114    HeadersMismatch,
115    /// Caller response buffer cannot hold the complete fixture body.
116    ResponseBufferTooSmall,
117    /// Internal cursor arithmetic failed closed.
118    CursorOverflow,
119    /// Another request changed the ordered cursor during this exchange.
120    ConcurrentRequest,
121    /// Fixture metadata could not be represented by the core transport.
122    InvalidFixtureMetadata,
123    /// The core response writer rejected fixture output.
124    ResponseWriterRejected,
125}
126
127impl_static_error!(MockError,
128    Self::Exhausted => "mock transport has no expected exchange remaining",
129    Self::MethodMismatch => "mock request method differs from expectation",
130    Self::TargetMismatch => "mock request target differs from expectation",
131    Self::BodyMismatch => "mock request body differs from expectation",
132    Self::HeadersMismatch => "mock request headers differ from expectation",
133    Self::ResponseBufferTooSmall => "mock response buffer is too small",
134    Self::CursorOverflow => "mock transport cursor overflowed",
135    Self::ConcurrentRequest => "mock transport cursor changed concurrently",
136    Self::InvalidFixtureMetadata => "mock fixture metadata is invalid",
137    Self::ResponseWriterRejected => "mock response writer rejected output",
138);
139
140/// Ordered no-allocation mock implementation of [`BlockingTransport`].
141pub struct MockTransport<'a> {
142    exchanges: &'a [MockExchange<'a>],
143    cursor: AtomicUsize,
144    endpoint: Option<EndpointIdentity<'a>>,
145}
146
147impl<'a> MockTransport<'a> {
148    /// Creates a mock over an ordered exchange slice.
149    #[must_use]
150    pub const fn new(exchanges: &'a [MockExchange<'a>]) -> Self {
151        Self {
152            exchanges,
153            cursor: AtomicUsize::new(0),
154            endpoint: None,
155        }
156    }
157
158    /// Binds the mock permanently to one normalized endpoint identity.
159    #[must_use]
160    pub const fn with_endpoint(mut self, endpoint: EndpointIdentity<'a>) -> Self {
161        self.endpoint = Some(endpoint);
162        self
163    }
164
165    /// Returns the number of exchanges not yet consumed.
166    #[must_use]
167    pub fn remaining(&self) -> usize {
168        self.exchanges
169            .len()
170            .saturating_sub(self.cursor.load(Ordering::Acquire))
171    }
172
173    /// Reports whether every expected exchange was consumed.
174    #[must_use]
175    pub fn is_complete(&self) -> bool {
176        self.remaining() == 0
177    }
178
179    fn send_inner(
180        &self,
181        request: TransportRequest<'_>,
182        response: &mut ResponseWriter<'_>,
183    ) -> Result<(), MockError> {
184        if response.is_committed() {
185            return Err(MockError::ResponseWriterRejected);
186        }
187        let mut response = response
188            .begin_attempt()
189            .map_err(|_| MockError::ResponseWriterRejected)?;
190        let completion = self.stage_inner(request, &mut response)?;
191        response
192            .commit_completion(completion)
193            .map_err(|_| MockError::ResponseWriterRejected)
194    }
195
196    fn stage_inner<'buffer>(
197        &self,
198        request: TransportRequest<'_>,
199        response: &mut impl MockResponseSink<'buffer>,
200    ) -> Result<ResponseCompletion, MockError> {
201        let cursor = self.cursor.load(Ordering::Acquire);
202        let exchange = self.exchanges.get(cursor).ok_or(MockError::Exhausted)?;
203        if request.method() != exchange.request.method() {
204            return Err(MockError::MethodMismatch);
205        }
206        if request.target() != exchange.request.target() {
207            return Err(MockError::TargetMismatch);
208        }
209        if request.body() != exchange.request.body() {
210            return Err(MockError::BodyMismatch);
211        }
212        if !request_headers_match(request.headers(), exchange.request.headers()) {
213            return Err(MockError::HeadersMismatch);
214        }
215        let next_cursor = cursor.checked_add(1).ok_or(MockError::CursorOverflow)?;
216        let completion = stage_response(&exchange.response, response)?;
217        self.cursor
218            .compare_exchange(cursor, next_cursor, Ordering::AcqRel, Ordering::Acquire)
219            .map_err(|_| MockError::ConcurrentRequest)?;
220        Ok(completion)
221    }
222}
223
224pub(crate) fn stage_response<'buffer>(
225    fixture: &ResponseFixture<'_>,
226    response: &mut impl MockResponseSink<'buffer>,
227) -> Result<ResponseCompletion, MockError> {
228    let _content_type = fixture
229        .content_type()
230        .map(ResponseContentType::new)
231        .transpose()
232        .map_err(|_| MockError::InvalidFixtureMetadata)?;
233    let rate_limit = fixture
234        .rate_limit()
235        .map(|value| value.into_rate_limit())
236        .transpose()
237        .map_err(|_| MockError::InvalidFixtureMetadata)?;
238    {
239        let response_headers = response
240            .headers_mut()
241            .map_err(|_| MockError::ResponseWriterRejected)?;
242        if let Some(source) = fixture.headers() {
243            for header in source.iter() {
244                response_headers
245                    .try_push(header.name(), header.value(), header.sensitivity())
246                    .map_err(|_| MockError::InvalidFixtureMetadata)?;
247            }
248        }
249        if let Some(value) = fixture.content_type() {
250            response_headers
251                .try_push("content-type", value.as_bytes(), HeaderSensitivity::Public)
252                .map_err(|_| MockError::InvalidFixtureMetadata)?;
253        }
254        if let Some(value) = rate_limit {
255            push_rate_limit_headers(response_headers, value)
256                .map_err(|_| MockError::InvalidFixtureMetadata)?;
257        }
258    }
259    let body_len = fixture
260        .body()
261        .write_to(
262            response
263                .body_mut()
264                .map_err(|_| MockError::ResponseWriterRejected)?,
265        )
266        .map_err(|error| match error {
267            FixtureBodyError::OutputTooSmall | FixtureBodyError::TooLarge => {
268                MockError::ResponseBufferTooSmall
269            }
270        })?;
271    let mut metadata = ResponseMetadata::EMPTY;
272    if let Some(value) = rate_limit {
273        metadata = metadata.with_rate_limit(value);
274    }
275    Ok(ResponseCompletion::new(
276        fixture.status(),
277        body_len,
278        metadata,
279    ))
280}
281
282pub(crate) trait MockResponseSink<'buffer> {
283    fn body_mut(&mut self) -> Result<&mut [u8], MockError>;
284    fn headers_mut(&mut self) -> Result<&mut ResponseHeaders<'buffer>, MockError>;
285}
286
287impl<'buffer> MockResponseSink<'buffer> for ResponseAttempt<'_, 'buffer> {
288    fn body_mut(&mut self) -> Result<&mut [u8], MockError> {
289        ResponseAttempt::body_mut(self).map_err(|_| MockError::ResponseWriterRejected)
290    }
291
292    fn headers_mut(&mut self) -> Result<&mut ResponseHeaders<'buffer>, MockError> {
293        ResponseAttempt::headers_mut(self).map_err(|_| MockError::ResponseWriterRejected)
294    }
295}
296
297impl<'buffer> MockResponseSink<'buffer> for AsyncResponseStaging<'_, 'buffer> {
298    fn body_mut(&mut self) -> Result<&mut [u8], MockError> {
299        AsyncResponseStaging::body_mut(self).map_err(|_| MockError::ResponseWriterRejected)
300    }
301
302    fn headers_mut(&mut self) -> Result<&mut ResponseHeaders<'buffer>, MockError> {
303        AsyncResponseStaging::headers_mut(self).map_err(|_| MockError::ResponseWriterRejected)
304    }
305}
306
307fn request_headers_match(actual: RequestHeaders<'_>, expected: RequestHeaders<'_>) -> bool {
308    let actual = actual.as_slice();
309    let expected = expected.as_slice();
310    actual.len() == expected.len()
311        && actual.iter().zip(expected).all(|(actual, expected)| {
312            actual.name() == expected.name()
313                && actual.value().as_str().as_bytes() == expected.value().as_str().as_bytes()
314                && actual.sensitivity() == expected.sensitivity()
315        })
316}
317
318fn push_rate_limit_headers(
319    headers: &mut ResponseHeaders,
320    rate_limit: cloud_sdk::rate_limit::RateLimit,
321) -> Result<(), ()> {
322    let mut storage = [0_u8; 20];
323    for (name, value) in [
324        ("ratelimit-limit", rate_limit.limit()),
325        ("ratelimit-remaining", rate_limit.remaining()),
326        ("ratelimit-reset", rate_limit.reset_epoch_seconds()),
327    ] {
328        let text = write_decimal(value, &mut storage).ok_or(())?;
329        headers
330            .try_push(name, text.as_bytes(), HeaderSensitivity::Public)
331            .map_err(|_| ())?;
332    }
333    Ok(())
334}
335
336fn write_decimal(value: u64, output: &mut [u8; 20]) -> Option<&str> {
337    let mut value = value;
338    let mut cursor = output.len();
339    loop {
340        cursor = cursor.checked_sub(1)?;
341        let digit = u8::try_from(value % 10).ok()?;
342        *output.get_mut(cursor)? = b'0'.checked_add(digit)?;
343        value /= 10;
344        if value == 0 {
345            break;
346        }
347    }
348    core::str::from_utf8(output.get(cursor..)?).ok()
349}
350
351impl BlockingTransport for MockTransport<'_> {
352    type Error = MockError;
353
354    fn send(
355        &self,
356        request: TransportRequest<'_>,
357        response: &mut ResponseWriter<'_>,
358    ) -> Result<(), Self::Error> {
359        self.send_inner(request, response)
360    }
361}
362
363impl BlockingAuthenticatedTransport for MockTransport<'_> {
364    type Error = MockError;
365
366    fn send_authenticated(
367        &self,
368        request: AuthenticatedRequest<'_, '_>,
369        response: &mut ResponseWriter<'_>,
370    ) -> Result<(), Self::Error> {
371        self.send_inner(request.transport_request(), response)
372    }
373}
374
375impl AsyncTransport for MockTransport<'_> {
376    type Error = MockError;
377
378    async fn send<'transport, 'request, 'writer, 'buffer>(
379        &'transport self,
380        request: TransportRequest<'request>,
381        mut response: AsyncResponseStaging<'writer, 'buffer>,
382    ) -> Result<ResponseCompletion, Self::Error>
383    where
384        'transport: 'writer,
385        'request: 'writer,
386        'buffer: 'writer,
387    {
388        self.stage_inner(request, &mut response)
389    }
390}
391
392impl AsyncAuthenticatedTransport for MockTransport<'_> {
393    type Error = MockError;
394
395    async fn send_authenticated<'transport, 'request, 'policy, 'writer, 'buffer>(
396        &'transport self,
397        request: AuthenticatedRequest<'request, 'policy>,
398        mut response: AsyncResponseStaging<'writer, 'buffer>,
399    ) -> Result<ResponseCompletion, Self::Error>
400    where
401        'transport: 'writer,
402        'request: 'writer,
403        'policy: 'writer,
404        'buffer: 'writer,
405    {
406        self.stage_inner(request.transport_request(), &mut response)
407    }
408}
409
410impl BoundTransport for MockTransport<'_> {
411    fn endpoint_identity(&self) -> Result<EndpointIdentity<'_>, EndpointIdentityError> {
412        self.endpoint.ok_or(EndpointIdentityError::UnboundTransport)
413    }
414}
415
416impl fmt::Debug for MockTransport<'_> {
417    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
418        formatter
419            .debug_struct("MockTransport")
420            .field("remaining", &self.remaining())
421            .finish_non_exhaustive()
422    }
423}
cloud_sdk_testkit/mock.rs

cloud_sdk_testkit/
mock.rs
