1//! Test support for GPUI.
2//!
3//! GPUI provides first-class support for testing, which includes a macro to run test that rely on having a context,
4//! and a test implementation of the `ForegroundExecutor` and `BackgroundExecutor` which ensure that your tests run
5//! deterministically even in the face of arbitrary parallelism.
6//!
7//! The output of the `gpui::test` macro is understood by other rust test runners, so you can use it with `cargo test`
8//! or `cargo-nextest`, or another runner of your choice.
9//!
10//! To make it possible to test collaborative user interfaces (like Zed) you can ask for as many different contexts
11//! as you need.
12//!
13//! ## Example
14//!
15//! ```
16//! use gpui;
17//!
18//! #[gpui::test]
19//! async fn test_example(cx: &TestAppContext) {
20//! assert!(true)
21//! }
22//!
23//! #[gpui::test]
24//! async fn test_collaboration_example(cx_a: &TestAppContext, cx_b: &TestAppContext) {
25//! assert!(true)
26//! }
27//! ```
28use crate::{Entity, Subscription, TestAppContext, TestDispatcher};
29use futures::StreamExt as _;
30use smol::channel;
31use std::{
32 env,
33 panic::{self, RefUnwindSafe},
34 pin::Pin,
35};
36
37/// Run the given test function with the configured parameters.
38/// This is intended for use with the `gpui::test` macro
39/// and generally should not be used directly.
40pub fn run_test(
41 num_iterations: usize,
42 explicit_seeds: &[u64],
43 max_retries: usize,
44 test_fn: &mut (dyn RefUnwindSafe + Fn(TestDispatcher, u64)),
45 on_fail_fn: Option<fn()>,
46) {
47 let (seeds, is_multiple_runs) = calculate_seeds(num_iterations as u64, explicit_seeds);
48
49 for seed in seeds {
50 let mut attempt = 0;
51 loop {
52 if is_multiple_runs {
53 eprintln!("seed = {seed}");
54 }
55 let result = panic::catch_unwind(|| {
56 let dispatcher = TestDispatcher::new(seed);
57 test_fn(dispatcher, seed);
58 });
59
60 match result {
61 Ok(_) => break,
62 Err(error) => {
63 if attempt < max_retries {
64 println!("attempt {} failed, retrying", attempt);
65 attempt += 1;
66 // The panic payload might itself trigger an unwind on drop:
67 // https://doc.rust-lang.org/std/panic/fn.catch_unwind.html#notes
68 std::mem::forget(error);
69 } else {
70 if is_multiple_runs {
71 eprintln!("failing seed: {seed}");
72 eprintln!(
73 "You can rerun from this seed by setting the environmental variable SEED to {seed}"
74 );
75 }
76 if let Some(on_fail_fn) = on_fail_fn {
77 on_fail_fn()
78 }
79 panic::resume_unwind(error);
80 }
81 }
82 }
83 }
84 }
85}
86
87fn calculate_seeds(
88 iterations: u64,
89 explicit_seeds: &[u64],
90) -> (impl Iterator<Item = u64> + '_, bool) {
91 let iterations = env::var("ITERATIONS")
92 .ok()
93 .map(|var| var.parse().expect("invalid ITERATIONS variable"))
94 .unwrap_or(iterations);
95
96 let env_num = env::var("SEED")
97 .map(|seed| seed.parse().expect("invalid SEED variable as integer"))
98 .ok();
99
100 let empty_range = || 0..0;
101
102 let iter = {
103 let env_range = if let Some(env_num) = env_num {
104 env_num..env_num + 1
105 } else {
106 empty_range()
107 };
108
109 // if `iterations` is 1 and !(`explicit_seeds` is non-empty || `SEED` is set), then add the run `0`
110 // if `iterations` is 1 and (`explicit_seeds` is non-empty || `SEED` is set), then discard the run `0`
111 // if `iterations` isn't 1 and `SEED` is set, do `SEED..SEED+iterations`
112 // otherwise, do `0..iterations`
113 let iterations_range = match (iterations, env_num) {
114 (1, None) if explicit_seeds.is_empty() => 0..1,
115 (1, None) | (1, Some(_)) => empty_range(),
116 (iterations, Some(env)) => env..env + iterations,
117 (iterations, None) => 0..iterations,
118 };
119
120 // if `SEED` is set, ignore `explicit_seeds`
121 let explicit_seeds = if env_num.is_some() {
122 &[]
123 } else {
124 explicit_seeds
125 };
126
127 env_range
128 .chain(iterations_range)
129 .chain(explicit_seeds.iter().copied())
130 };
131 let is_multiple_runs = iter.clone().nth(1).is_some();
132 (iter, is_multiple_runs)
133}
134
135/// A test struct for converting an observation callback into a stream.
136pub struct Observation<T> {
137 rx: Pin<Box<channel::Receiver<T>>>,
138 _subscription: Subscription,
139}
140
141impl<T: 'static> futures::Stream for Observation<T> {
142 type Item = T;
143
144 fn poll_next(
145 mut self: std::pin::Pin<&mut Self>,
146 cx: &mut std::task::Context<'_>,
147 ) -> std::task::Poll<Option<Self::Item>> {
148 self.rx.poll_next_unpin(cx)
149 }
150}
151
152/// observe returns a stream of the change events from the given `Entity`
153pub fn observe<T: 'static>(entity: &Entity<T>, cx: &mut TestAppContext) -> Observation<()> {
154 let (tx, rx) = smol::channel::unbounded();
155 let _subscription = cx.update(|cx| {
156 cx.observe(entity, move |_, _| {
157 let _ = smol::block_on(tx.send(()));
158 })
159 });
160 let rx = Box::pin(rx);
161
162 Observation { rx, _subscription }
163}