3 releases
0.1.2 | Jul 23, 2024 |
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0.1.1 | Jun 26, 2024 |
0.1.0 | Jun 24, 2024 |
#441 in Testing
60KB
1.5K
SLoC
Spectest - lightweight BDD testing for Rust
A lightweight library for defining behavior-driven development (BDD) style tests in exernal files and running them with cargo test
.
This can be seen as a successor / alternative of the datadriven crate.
Please consult the spectest
docs and the integration tests for details.
lib.rs
:
A lightweight library for defining behavior-driven development (BDD) style
tests in external files and running them with cargo test
.
To write a test:
- Implement a
Handler
that interpretsBackground
andExample
sections defined in your spec file. - Write a test that calls [
run
] with aHandler
instance and a path that points to a spec file. You can also useglob_test
to derive one such test for each spec file in a given folder (including subfolders).
Example
Here is a minimal example:
use spectest;
struct MevalHandler<'a> {
ctx: meval::Context<'a>,
}
impl<'a> MevalHandler<'a> {
fn new() -> Self {
Self {
ctx: meval::Context::new(),
}
}
}
impl<'a> spectest::Handler for MevalHandler<'a> {
type Error = String;
fn example(&mut self, example: &mut spectest::Example) -> Result<(), Self::Error> {
let Some(input) = example.when.get("input") else {
let msg = format!("missing `input` definition in the 'When' spec");
return Err(msg);
};
let input = match input.parse::<meval::Expr>() {
Ok(expr) => expr,
Err(err) => {
let msg = format!("cannot parse `input` expression `{input}`: {err}");
return Err(msg);
}
};
match input.eval_with_context(self.ctx.clone()) {
Ok(value) => {
example.then.insert("result", value.to_string() + "\n");
}
Err(err) => {
let msg = format!("cannot evaluate expression: {err}\n");
example.then.insert("result", msg);
}
}
Ok(())
}
}
#[spectest::glob_test("testdata/integration/**/*.md")]
fn test_meval(path: &str) {
let mut handler = MevalHandler::new();
spectest::run(path, &mut handler);
}
Assuming that the testdata/integration
folder contains a single called
calculator.md
, one can run the test against this file as follows:
# Expand the prefix to narrow the set of tested spec files
cargo test test_meval_
It is also possible to mass-rewrite failing tests after fixing/updating the
behavior of the meval
library under test as follows
REWRITE_SPECS=true cargo test test_calculator
For a more elaborated version that also updates the evaluation context
depending on the currently active Background
sections, see the
test/integration.rs
in the source repository.
Dependencies
~2.3–3.5MB
~59K SLoC