GoogleTest

The GoogleTest crate allows for flexible test assertions using matchers:

  1. use googletest::prelude::*;
  3. #[googletest::test]
  4. fn test_elements_are() {
  5.     let value = vec!["foo", "bar", "baz"];
  6.     expect_that!(value, elements_are!(eq("foo"), lt("xyz"), starts_with("b")));
  7. }

如果我们将最后一个元素更改为 "!"，测试将失败，并会提供详细的错误消息来指出错误的位置：

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

This slide should take about 5 minutes.

  • GoogleTest 不是 Rust Playground 的一部分，因此您需要在本地环境中运行此示例。使用 cargo add googletest 快速将其添加到现有 Cargo 项目中。

  • use googletest::prelude::*; 行会导入一些 常用的宏和类型。

  • 这只是冰山一角，还有很多内置匹配器。

  • A particularly nice feature is that mismatches in multi-line strings are shown as a diff:

  1. #[test]
  2. fn test_multiline_string_diff() {
  3.     let haiku = "Memory safety found,\n\
  4.                  Rust's strong typing guides the way,\n\
  5.                  Secure code you'll write.";
  6.     assert_that!(
  7.         haiku,
  8.         eq("Memory safety found,\n\
  9.             Rust's silly humor guides the way,\n\
  10.             Secure code you'll write.")
  11.     );
  12. }

显示用颜色标识的差异（此处未显示颜色）：

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