exercism, yo

rust/hello-world/GETTING_STARTED.md

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+# Getting Started
+
+These exercises lean on Test-Driven Development (TDD), but they're not
+an exact match.
+
+The following steps assume that you are in the same directory as the exercise.
+
+You must have Rust installed.
+Follow the [Installation chapter in the Rust book](https://doc.rust-lang.org/book/ch01-01-installation.html).
+The [Rust language section](http://exercism.org/languages/rust)
+section from exercism is also useful.
+
+## Step 1
+
+Run the test suite. It can be run with `cargo`, which is installed with Rust.
+
+```sh
+$ cargo test
+```
+
+This will compile the `hello-world` crate and run the test, which fails.
+
+```sh
+running 1 test
+test hello_world ... FAILED
+
+failures:
+
+---- hello_world stdout ----
+thread 'hello_world' panicked at 'assertion failed: `(left == right)`
+(left: `"Hello, World!"`, right: `"Goodbye, Mars!"`)', tests/hello-world.rs:5
+
+failures:
+    hello_world
+
+test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured
+```
+
+### Understanding Test Failures
+
+The `hello_world` failure states that it is expecting the value,
+`"Hello, World!"`, to be returned from `hello()`.
+The left side of the assertion (at line 5) should be equal to the right side.
+
+```sh
+---- hello_world stdout ----
+thread 'hello_world' panicked at 'assertion failed: `(left == right)`
+(left: `"Hello, World!"`, right: `"Goodbye, Mars!"`)', tests/hello-world.rs:5
+```
+
+### Fixing the Error
+
+To fix it, open up `src/lib.rs` and change the `hello` function to return
+`"Hello, World!"` instead of `"Goodbye, Mars!"`.
+
+```rust
+pub fn hello() -> &'static str {
+    "Hello, World!"
+}
+```
+
+## Step 2
+
+Run the test again. This time, it will pass.
+
+```sh
+running 0 tests
+
+test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured
+
+     Running target/debug/deps/hello_world-bd1f06dc726ef14f
+
+running 1 test
+test hello_world ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured
+
+   Doc-tests hello-world
+
+running 0 tests
+
+test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured
+```
+
+## Submit
+
+Once the test is passing, you can submit your code with the following
+command:
+
+```sh
+$ exercism submit
+```