A test runner that builds tests with rustc or cargo (or any other compiler with some configuration effort) and compares the output of the compiler with a file that you check into git. This allows you to test how your libraries show up to your users when the library is used wrongly and emits errors. ## Usage See [examples directory](examples) for how to use this in your own crate. To be able to use it with `cargo test`, you need to put ```toml [[test]] name = "your_test_file" harness = false ``` into your `Cargo.toml`, otherwise `cargo test` will only look for `#[test]`s and not run your `fn main()` that actually executes `ui_test` ## Implicit (and possibly surprising) behavior * Tests are run in order of their filenames (files first, then recursing into folders). So if you have any slow tests, prepend them with a small integral number to make them get run first, taking advantage of parallelism as much as possible (instead of waiting for the slow tests at the end). * `cargo test --test your_test_name -- --help` lists the commands you can specify for filtering, blessing and making your tests less verbose. * Since `cargo test` on its own runs all tests, using `cargo test -- --check` will not work on its own, but `cargo test -- --quiet` and `cargo test -- some_test_name` will work just fine, as the CLI matches. * if there is a `.stdin` file with the same filename as your test, it will be piped as standard input to your program. ## Supported comment annotations If your test tests for failure, you need to add a `//~` annotation where the error is happening to ensure that the test will always keep failing at the annotated line. These comments can take two forms: * `//~ LEVEL: XXX` matches by error level and message text * `LEVEL` can be one of the following (descending order): `ERROR`, `HELP`, `WARN` or `NOTE` * If a level is specified explicitly, *all* diagnostics of that level or higher need an annotation. To avoid this see `//@require-annotations-for-level` * This checks the output *before* normalization, so you can check things that get normalized away, but need to be careful not to accidentally have a pattern that differs between platforms. * if `XXX` is of the form `/XXX/` it is treated as a regex instead of a substring and will succeed if the regex matches. * `//~ CODE` matches by diagnostic code. * `CODE` can take multiple forms such as: `E####`, `lint_name`, `tool::lint_name`. * This will only match a diagnostic at the `ERROR` level. In order to change how a single test is tested, you can add various `//@` comments to the test. Any other comments will be ignored, and all `//@` comments must be formatted precisely as their command specifies, or the test will fail without even being run. * `//@ignore-C` avoids running the test when condition `C` is met. * `C` can be `target: XXX YYY`, which checks whether the target triple contains `XXX` or `YYY`. * `C` can be `host: XXX YYY`, which checks whether the host triple contains `XXX` or `YYY`. * `C` can also be `bitwidth:` followed by one or more space separated integer size like `64`, `32` or `16`. * `C` can also be `on-host`, which will only run the test during cross compilation testing. * `//@only-C` **only** runs the test when condition `C` is met. The conditions are the same as with `ignore`. * `//@needs-asm-support` **only** runs the test when the target supports `asm!`. * `//@stderr-per-bitwidth` produces one stderr file per bitwidth, as they may differ significantly sometimes * `//@error-in-other-file: XXX` can be used to check for errors that can't have `//~` patterns due to being reported in other files. * `//@revisions: XXX YYY` runs the test once for each space separated name in the list * emits one stderr file per revision * `//~` comments can be restricted to specific revisions by adding the revision name after the `~` in square brackets: `//~[XXX]` * `//@` comments can be restricted to specific revisions by adding the revision name after the `@` in square brackets: `//@[XXX]` * Note that you cannot add revisions to the `revisions` command. * `//@compile-flags: XXX` appends `XXX` to the command line arguments passed to the rustc driver * you can specify this multiple times, and all the flags will accumulate * `//@rustc-env: XXX=YYY` sets the env var `XXX` to `YYY` for the rustc driver execution. * for Miri these env vars are used during compilation via rustc and during the emulation of the program * you can specify this multiple times, accumulating all the env vars * `//@normalize-stderr-test: "REGEX" -> "REPLACEMENT"` replaces all matches of `REGEX` in the stderr with `REPLACEMENT`. The replacement may specify `$1` and similar backreferences to paste captures. * you can specify multiple such commands, there is no need to create a single regex that handles multiple replacements that you want to perform. * `//@require-annotations-for-level: LEVEL` can be used to change the level of diagnostics that require a corresponding annotation. * this is only useful if there are any annotations like `HELP`, `WARN` or `NOTE`, as these would automatically require annotations for all other diagnostics of the same or higher level. * `//@check-pass` requires that a test has no error annotations, emits no errors, and exits successfully with exit/status code 0. * `//@edition: EDITION` overwrites the default edition (2021) to the given edition. * `//@no-rustfix` do not run [rustfix] on tests that have machine applicable suggestions. * `//@aux-build: filename` looks for a file in the `auxiliary` directory (within the directory of the test), compiles it as a library and links the current crate against it. This allows you import the crate with `extern crate` or just via `use` statements. This will automatically detect aux files that are proc macros and build them as proc macros. * `//@run` compiles the test and runs the resulting binary. The resulting binary must exit successfully. Stdout and stderr are taken from the resulting binary. Any warnings during compilation are ignored. * You can also specify a different exit code/status that is expected via e.g. `//@run: 1` or `//@run: 101` (the latter is the standard Rust exit code for panics). * run tests collect the run output into `.run.stderr` and `.run.stdout` respectively. * if a `.run.stdin` file exists, it will be piped as standard input to your test's execution. [rustfix]: https://github.com/rust-lang/rustfix ## Significant differences to compiletest-rs * `ignore-target-xxx` and `only-target-xxx` requires the `target-` prefix before the `xxx` substring to be matched against target triples, whereas compiletest allows plain `ignore-xxx` without the `target-` prefix. The substring `xxx` must also be a substring of target triples, and special collections such as `macos`/`unix` in compiletest is not supported. * only supports `ui` tests * tests are run in named order, so you can prefix slow tests with `0` in order to make them get run first * `aux-build`s require specifying nested aux builds explicitly and will not allow you to reference sibling `aux-build`s' artifacts.