ferridriver_expect/
poll.rs

1//! Generic async polling primitives shared by the test runner's
2//! `Expect<T>` and the script-layer `ExpectJs` binding.
3
4use std::future::Future;
5use std::time::Duration;
6
7use crate::AssertionFailure;
8
9/// Default expect timeout (5 seconds, matching Playwright).
10pub const DEFAULT_EXPECT_TIMEOUT: Duration = Duration::from_secs(5);
11
12/// Retry intervals matching Playwright: [100, 250, 500, 1000, 1000, ...]
13pub const POLL_INTERVALS: &[u64] = &[100, 250, 500, 1000];
14
15/// Internal match error used during polling — captured per attempt and
16/// rendered into the final [`AssertionFailure`] when the deadline expires.
17#[derive(Debug, Clone)]
18pub struct MatchError {
19  pub expected: String,
20  pub received: String,
21}
22
23impl MatchError {
24  pub fn new(expected: impl Into<String>, received: impl Into<String>) -> Self {
25    Self {
26      expected: expected.into(),
27      received: received.into(),
28    }
29  }
30}
31
32/// Context for an expect assertion — used to build Playwright-style
33/// error messages.
34#[derive(Debug, Clone)]
35pub struct ExpectContext {
36  /// e.g. `"toHaveText"`, `"toBeVisible"`.
37  pub method: &'static str,
38  /// e.g. `"locator('h1')"`, `"page"`.
39  pub subject: String,
40  /// Whether this is a negated assertion (`.not`).
41  pub is_not: bool,
42}
43
44/// Poll a condition until it passes or timeout. Produces a
45/// Playwright-style error message with method name, locator,
46/// expected/received, and call log.
47pub async fn poll_until<F, Fut>(timeout: Duration, ctx: ExpectContext, mut check: F) -> Result<(), AssertionFailure>
48where
49  F: FnMut() -> Fut,
50  Fut: Future<Output = Result<(), MatchError>>,
51{
52  let deadline = tokio::time::Instant::now() + timeout;
53  let mut last_error: Option<MatchError>;
54  let mut interval_idx = 0;
55  let mut call_log: Vec<String> = Vec::new();
56  call_log.push(format!("expect.{} with timeout {}ms", ctx.method, timeout.as_millis()));
57  call_log.push(format!("waiting for {}", ctx.subject));
58
59  loop {
60    match check().await {
61      Ok(()) => return Ok(()),
62      Err(e) => {
63        call_log.push(format!("  unexpected value {}", e.received));
64        last_error = Some(e);
65        let interval_ms = POLL_INTERVALS
66          .get(interval_idx)
67          .copied()
68          .unwrap_or_else(|| POLL_INTERVALS.last().copied().unwrap_or(1000));
69        interval_idx += 1;
70
71        let sleep_dur = Duration::from_millis(interval_ms);
72        if tokio::time::Instant::now() + sleep_dur > deadline {
73          break;
74        }
75        tokio::time::sleep(sleep_dur).await;
76      },
77    }
78  }
79
80  let err = last_error.unwrap_or_else(|| MatchError::new("(unknown)", "(unknown)"));
81
82  let not_str = if ctx.is_not { ".not" } else { "" };
83  let timeout_ms = timeout.as_millis();
84
85  let call_log_str = if call_log.is_empty() {
86    String::new()
87  } else {
88    format!(
89      "\n\nCall log:\n{}",
90      call_log
91        .iter()
92        .map(|l| format!("  - {l}"))
93        .collect::<Vec<_>>()
94        .join("\n")
95    )
96  };
97
98  let message = format!(
99    "expect({subject}){not_str}.{method}() failed\n\n\
100     Locator:  {locator}\n\
101     Expected: {expected}\n\
102     Received: {received}\n\
103     Timeout:  {timeout_ms}ms\
104     {call_log_str}",
105    subject = ctx.subject,
106    method = ctx.method,
107    locator = ctx.subject,
108    expected = err.expected,
109    received = err.received,
110  );
111
112  let diff = format!("Expected: {}\nReceived: {}", err.expected, err.received);
113
114  Err(AssertionFailure::new(message, Some(diff)))
115}
ferridriver_expect/poll.rs

ferridriver_expect/
poll.rs
