5.1 GoogleTest

译文 · 基于 Comprehensive Rust

原文链接: https://google.github.io/comprehensive-rust/android/testing/googletest.html

5.1 GoogleTest

GoogleTest crate 允许使用 matcher 做灵活的测试断言：

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// Copyright 2024 Google LLC
// SPDX-License-Identifier: Apache-2.0
use googletest::prelude::*;

#[googletest::test]
fn test_elements_are() {
    let value = vec!["foo", "bar", "baz"];
    expect_that!(value, elements_are!(eq(&"foo"), lt(&"xyz"), starts_with("b")));
}

若把最后一个元素改成 "!"，测试会失败，并给出精确定位错误的结构化错误信息：

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---- test_elements_are stdout ----
Value of: value
Expected: has elements:
  0. is equal to "foo"
  1. is less than "xyz"
  2. starts with prefix "!"
Actual: ["foo", "bar", "baz"],
  where element #2 is "baz", which does not start with "!"
  at src/testing/googletest.rs:6:5
Error: See failure output above

• GoogleTest 不在 Rust Playground 中，因此需要在本地环境运行本示例。使用 cargo add googletest 可快速把它加到现有 Cargo 项目。

• use googletest::prelude::*; 这行会导入一组常用宏与类型。

• 这只是皮毛，还有许多内置 matcher。建议阅读 “Advanced testing for Rust applications” 的第一章，这是一门自引导的 Rust 课程：它提供对该库的引导式介绍，并配有练习，帮助你熟悉 googletest 宏、matcher 及其整体理念。

• 一个特别好用的特性是：多行字符串中的不匹配会以 diff 形式显示：

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// Copyright 2024 Google LLC // SPDX-License-Identifier: Apache-2.0 #[test] fn test_multiline_string_diff() { let haiku = "Memory safety found,\n\ Rust's strong typing guides the way,\n\ Secure code you'll write."; assert_that!( haiku, eq("Memory safety found,\n\ Rust's silly humor guides the way,\n\ Secure code you'll write.") ); }

会显示带颜色的 diff（此处不显示颜色）：

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Value of: haiku Expected: is equal to "Memory safety found,\nRust's silly humor guides the way,\nSecure code you'll write." Actual: "Memory safety found,\nRust's strong typing guides the way,\nSecure code you'll write.", which isn't equal to "Memory safety found,\nRust's silly humor guides the way,\nSecure code you'll write." Difference(-actual / +expected): Memory safety found, -Rust's strong typing guides the way, +Rust's silly humor guides the way, Secure code you'll write. at src/testing/googletest.rs:17:5

• 该 crate 是 GoogleTest for C++ 的 Rust 移植。