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Nov 2, 2016
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Update "Testing" chapter for 1.12 #37484

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74 changes: 39 additions & 35 deletions src/doc/book/testing.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,11 @@ Cargo will automatically generate a simple test when you make a new project.
Here's the contents of `src/lib.rs`:

```rust
# fn main() {}
#[test]
fn it_works() {
#[cfg(test)]
mod tests {
#[test]
fn it_works() {
}
}
```

Expand All @@ -36,11 +38,11 @@ currently has no body. That's good enough to pass! We can run the tests with

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test it_works ... ok
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

Expand All @@ -56,7 +58,7 @@ for the test we wrote, and another for documentation tests. We'll talk about
those later. For now, see this line:

```text
test it_works ... ok
test tests::it_works ... ok
```

Note the `it_works`. This comes from the name of our function:
Expand Down Expand Up @@ -89,31 +91,30 @@ run our tests again:

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test it_works ... FAILED
test tests::it_works ... FAILED

failures:

---- it_works stdout ----
thread 'it_works' panicked at 'assertion failed: false', /home/steve/tmp/adder/src/lib.rs:3

---- test::it_works stdout ----
thread 'tests::it_works' panicked at 'assertion failed: false', src/lib.rs:5


failures:
it_works
tests::it_works

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured

thread 'main' panicked at 'Some tests failed', /home/steve/src/rust/src/libtest/lib.rs:247
error: test failed
```

Rust indicates that our test failed:

```text
test it_works ... FAILED
test tests::it_works ... FAILED
```

And that's reflected in the summary line:
Expand Down Expand Up @@ -159,11 +160,11 @@ This test will now succeed if we `panic!` and fail if we complete. Let's try it:

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test it_works ... ok
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

Expand Down Expand Up @@ -191,11 +192,11 @@ passes:

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test it_works ... ok
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

Expand Down Expand Up @@ -262,8 +263,8 @@ not:

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 2 tests
test expensive_test ... ignored
Expand All @@ -282,7 +283,7 @@ The expensive tests can be run explicitly using `cargo test -- --ignored`:

```bash
$ cargo test -- --ignored
Running target/adder-91b3e234d4ed382a
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test expensive_test ... ok
Expand All @@ -302,8 +303,11 @@ which is why the command is `cargo test -- --ignored`.
# The `tests` module

There is one way in which our existing example is not idiomatic: it's
missing the `tests` module. The idiomatic way of writing our example
looks like this:
missing the `tests` module. You might have noticed this test module was
present in the code that was initially generated with `cargo new` but
was missing from our last example. Let's explain what this does.

The idiomatic way of writing our example looks like this:

```rust,ignore
# fn main() {}
Expand Down Expand Up @@ -356,8 +360,8 @@ Note the different `use` line. Now we run our tests:
```bash
$ cargo test
Updating registry `https://github.com/rust-lang/crates.io-index`
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test tests::it_works ... ok
Expand Down Expand Up @@ -404,15 +408,15 @@ Let's run them:

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/you/projects/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0 (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

Running target/lib-c18e7d3494509e74
Running target/debug/integration_test-68064b69521c828a

running 1 test
test it_works ... ok
Expand Down Expand Up @@ -490,15 +494,15 @@ Let's run the tests again:

```bash
$ cargo test
Compiling adder v0.0.1 (file:///home/steve/tmp/adder)
Running target/adder-91b3e234d4ed382a
Compiling adder v0.1.0. (file:///home/you/projects/adder)
Running target/debug/deps/adder-91b3e234d4ed382a

running 1 test
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

Running target/lib-c18e7d3494509e74
Running target/debug/integration_test-68064b69521c828a

running 1 test
test it_works ... ok
Expand Down