11.8 忽略测试

11.8.1. 忽略某些测试，运行其余测试

有些测试运行起来非常耗时，所以在大多数情况下，运行cargo test时可能想忽略它们，除非显式运行这些测试。

对于这些测试，Rust提供了ignore属性，将它们标记为默认不运行。

看个例子：

#![allow(unused)]
fn main() {
#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_works() {
        let result = add(2, 2);
        assert_eq!(result, 4);
    }

    #[test]
    #[ignore]
    fn expensive_test() {
        assert_eq!(5, 1 + 1 + 1 + 1 + 1)
    }
}
}

因为expensive_test加了ignore属性，所以在cargo test下不会运行，除非你显式要求运行它。

测试输出如下：

$ cargo test
   Compiling adder v0.1.0 (file:///projects/adder)
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.10s
     Running unittests src/lib.rs (target/debug/deps/adder-302521ba8d0f0bdf)

running 2 tests
test tests::expensive_test ... ignored
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.00s

   Doc-tests adder

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

11.8.2. 只运行被忽略的测试

如何只运行被忽略的测试呢？加上参数cargo test -- --ignored：

$ cargo test -- --ignored
   Compiling adder v0.1.0 (file:///projects/adder)
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.11s
     Running unittests src/lib.rs (target/debug/deps/adder-302521ba8d0f0bdf)

running 1 test
test tests::expensive_test ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 1 filtered out; finished in 0.00s

   Doc-tests adder

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

控制程序运行哪些测试，可以确保cargo test快速返回。如果时间充裕，想运行所有测试（包括被忽略的和未被忽略的），就用cargo test -- --include-ignored。