Rust: completed Hello World, Reverse String, Difference of Squares

rust/gigasecond/.exercism/config.json

@@ -0,0 +1,45 @@
+{
+  "authors": [
+    "IanWhitney"
+  ],
+  "contributors": [
+    "andy5995",
+    "ashleygwilliams",
+    "cbzehner",
+    "coriolinus",
+    "cwhakes",
+    "EduardoBautista",
+    "efx",
+    "ErikSchierboom",
+    "houhoulis",
+    "IanWhitney",
+    "janczer",
+    "leoyvens",
+    "lutostag",
+    "mkantor",
+    "nfiles",
+    "NieDzejkob",
+    "ocstl",
+    "petertseng",
+    "rofrol",
+    "sacherjj",
+    "stringparser",
+    "xakon",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/gigasecond.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Given a moment, determine the moment that would be after a gigasecond has passed.",
+  "source": "Chapter 9 in Chris Pine's online Learn to Program tutorial.",
+  "source_url": "https://pine.fm/LearnToProgram/?Chapter=09"
+}

rust/gigasecond/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"rust","exercise":"gigasecond","id":"46cf4dcc2c1d42f48213bc4054d72a04","url":"https://exercism.org/tracks/rust/exercises/gigasecond","handle":"Chomp1295","is_requester":true,"auto_approve":false}

rust/gigasecond/.gitignore

@@ -0,0 +1,8 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+**/*.rs.bk
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
+Cargo.lock

rust/gigasecond/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+edition = "2021"
+name = "gigasecond"
+version = "2.0.0"
+
+[dependencies]
+time = "0.3"

rust/gigasecond/HELP.md

@@ -0,0 +1,86 @@
+# Help
+
+## Running the tests
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test.
+
+If you wish to run _only ignored_ tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+If you are using Rust 1.51 or later, you can run _all_ tests with
+
+```bash
+$ cargo test -- --include-ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored, use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the online [test documentation][rust-tests].
+
+[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/lib.rs Cargo.toml` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Rust track's documentation](https://exercism.org/docs/tracks/rust)
+- The [Rust track's programming category on the forum](https://forum.exercism.org/c/programming/rust)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Submitting the solution
+
+Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.
+
+## Feedback, Issues, Pull Requests
+
+The GitHub [track repository][github] is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide].
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[help-page]: https://exercism.org/tracks/rust/learning
+[github]: https://github.com/exercism/rust
+[contribution guide]: https://exercism.org/docs/community/contributors

rust/gigasecond/README.md

@@ -0,0 +1,76 @@
+# Gigasecond
+
+Welcome to Gigasecond on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Introduction
+
+The way we measure time is kind of messy.
+We have 60 seconds in a minute, and 60 minutes in an hour.
+This comes from ancient Babylon, where they used 60 as the basis for their number system.
+We have 24 hours in a day, 7 days in a week, and how many days in a month?
+Well, for days in a month it depends not only on which month it is, but also on what type of calendar is used in the country you live in.
+
+What if, instead, we only use seconds to express time intervals?
+Then we can use metric system prefixes for writing large numbers of seconds in more easily comprehensible quantities.
+
+- A food recipe might explain that you need to let the brownies cook in the oven for two kiloseconds (that's two thousand seconds).
+- Perhaps you and your family would travel to somewhere exotic for two megaseconds (that's two million seconds).
+- And if you and your spouse were married for _a thousand million_ seconds, you would celebrate your one gigasecond anniversary.
+
+~~~~exercism/note
+If we ever colonize Mars or some other planet, measuring time is going to get even messier.
+If someone says "year" do they mean a year on Earth or a year on Mars?
+
+The idea for this exercise came from the science fiction novel ["A Deepness in the Sky"][vinge-novel] by author Vernor Vinge.
+In it the author uses the metric system as the basis for time measurements.
+
+[vinge-novel]: https://www.tor.com/2017/08/03/science-fiction-with-something-for-everyone-a-deepness-in-the-sky-by-vernor-vinge/
+~~~~
+
+## Instructions
+
+Your task is to determine the date and time one gigasecond after a certain date.
+
+A gigasecond is one thousand million seconds.
+That is a one with nine zeros after it.
+
+If you were born on _January 24th, 2015 at 22:00 (10:00:00pm)_, then you would be a gigasecond old on _October 2nd, 2046 at 23:46:40 (11:46:40pm)_.
+
+If you're unsure what operations you can perform on `PrimitiveDateTime` take a look at the [time crate](https://docs.rs/time) which is listed as a dependency in the `Cargo.toml` file for this exercise.
+
+## Source
+
+### Created by
+
+- @IanWhitney
+
+### Contributed to by
+
+- @andy5995
+- @ashleygwilliams
+- @cbzehner
+- @coriolinus
+- @cwhakes
+- @EduardoBautista
+- @efx
+- @ErikSchierboom
+- @houhoulis
+- @IanWhitney
+- @janczer
+- @leoyvens
+- @lutostag
+- @mkantor
+- @nfiles
+- @NieDzejkob
+- @ocstl
+- @petertseng
+- @rofrol
+- @sacherjj
+- @stringparser
+- @xakon
+- @ZapAnton
+
+### Based on
+
+Chapter 9 in Chris Pine's online Learn to Program tutorial. - https://pine.fm/LearnToProgram/?Chapter=09

rust/gigasecond/src/lib.rs

@@ -0,0 +1,6 @@
+use time::{Duration, PrimitiveDateTime as DateTime};
+
+// Returns a DateTime one billion seconds after start.
+pub fn after(start: DateTime) -> DateTime {
+    start + Duration::seconds(1_000_000_000)
+}

rust/gigasecond/tests/gigasecond.rs

@@ -0,0 +1,48 @@
+use time::PrimitiveDateTime as DateTime;
+
+/// Create a datetime from the given numeric point in time.
+///
+/// Panics if any field is invalid.
+fn dt(year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8) -> DateTime {
+    use time::{Date, Time};
+
+    DateTime::new(
+        Date::from_calendar_date(year, month.try_into().unwrap(), day).unwrap(),
+        Time::from_hms(hour, minute, second).unwrap(),
+    )
+}
+
+#[test]
+fn date() {
+    let start_date = dt(2011, 4, 25, 0, 0, 0);
+
+    assert_eq!(gigasecond::after(start_date), dt(2043, 1, 1, 1, 46, 40));
+}
+
+#[test]
+fn another_date() {
+    let start_date = dt(1977, 6, 13, 0, 0, 0);
+
+    assert_eq!(gigasecond::after(start_date), dt(2009, 2, 19, 1, 46, 40));
+}
+
+#[test]
+fn third_date() {
+    let start_date = dt(1959, 7, 19, 0, 0, 0);
+
+    assert_eq!(gigasecond::after(start_date), dt(1991, 3, 27, 1, 46, 40));
+}
+
+#[test]
+fn datetime() {
+    let start_date = dt(2015, 1, 24, 22, 0, 0);
+
+    assert_eq!(gigasecond::after(start_date), dt(2046, 10, 2, 23, 46, 40));
+}
+
+#[test]
+fn another_datetime() {
+    let start_date = dt(2015, 1, 24, 23, 59, 59);
+
+    assert_eq!(gigasecond::after(start_date), dt(2046, 10, 3, 1, 46, 39));
+}

rust/hello-world/.exercism/config.json

@@ -0,0 +1,42 @@
+{
+  "authors": [
+    "EduardoBautista"
+  ],
+  "contributors": [
+    "ashleygwilliams",
+    "ClashTheBunny",
+    "coriolinus",
+    "cwhakes",
+    "dvoytik",
+    "EduardoBautista",
+    "efx",
+    "ErikSchierboom",
+    "hydhknn",
+    "IanWhitney",
+    "ijanos",
+    "kytrinyx",
+    "lutostag",
+    "nfiles",
+    "petertseng",
+    "regnerjr",
+    "rofrol",
+    "stringparser",
+    "xakon",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/hello-world.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Exercism's classic introductory exercise. Just say \"Hello, World!\".",
+  "source": "This is an exercise to introduce users to using Exercism",
+  "source_url": "https://en.wikipedia.org/wiki/%22Hello,_world!%22_program"
+}

rust/hello-world/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"rust","exercise":"hello-world","id":"8fc7d235b9714b939df049625c414d2c","url":"https://exercism.org/tracks/rust/exercises/hello-world","handle":"Chomp1295","is_requester":true,"auto_approve":false}

rust/hello-world/.gitignore

@@ -0,0 +1,8 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+**/*.rs.bk
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
+Cargo.lock

rust/hello-world/Cargo.toml

@@ -0,0 +1,4 @@
+[package]
+edition = "2021"
+name = "hello-world"
+version = "1.1.0"

rust/hello-world/GETTING_STARTED.md

@@ -0,0 +1,92 @@
+# 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
+```

rust/hello-world/HELP.md

@@ -0,0 +1,86 @@
+# Help
+
+## Running the tests
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test.
+
+If you wish to run _only ignored_ tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+If you are using Rust 1.51 or later, you can run _all_ tests with
+
+```bash
+$ cargo test -- --include-ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored, use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the online [test documentation][rust-tests].
+
+[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/lib.rs Cargo.toml` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Rust track's documentation](https://exercism.org/docs/tracks/rust)
+- The [Rust track's programming category on the forum](https://forum.exercism.org/c/programming/rust)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Submitting the solution
+
+Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.
+
+## Feedback, Issues, Pull Requests
+
+The GitHub [track repository][github] is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide].
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[help-page]: https://exercism.org/tracks/rust/learning
+[github]: https://github.com/exercism/rust
+[contribution guide]: https://exercism.org/docs/community/contributors

rust/hello-world/README.md

@@ -0,0 +1,56 @@
+# Hello World
+
+Welcome to Hello World on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+The classical introductory exercise.
+Just say "Hello, World!".
+
+["Hello, World!"][hello-world] is the traditional first program for beginning programming in a new language or environment.
+
+The objectives are simple:
+
+- Modify the provided code so that it produces the string "Hello, World!".
+- Run the test suite and make sure that it succeeds.
+- Submit your solution and check it at the website.
+
+If everything goes well, you will be ready to fetch your first real exercise.
+
+[hello-world]: https://en.wikipedia.org/wiki/%22Hello,_world!%22_program
+
+In the Rust track, tests are run using the command `cargo test`.
+
+## Source
+
+### Created by
+
+- @EduardoBautista
+
+### Contributed to by
+
+- @ashleygwilliams
+- @ClashTheBunny
+- @coriolinus
+- @cwhakes
+- @dvoytik
+- @EduardoBautista
+- @efx
+- @ErikSchierboom
+- @hydhknn
+- @IanWhitney
+- @ijanos
+- @kytrinyx
+- @lutostag
+- @nfiles
+- @petertseng
+- @regnerjr
+- @rofrol
+- @stringparser
+- @xakon
+- @ZapAnton
+
+### Based on
+
+This is an exercise to introduce users to using Exercism - https://en.wikipedia.org/wiki/%22Hello,_world!%22_program

rust/hello-world/src/lib.rs

@@ -0,0 +1,4 @@
+// &'static is a "lifetime specifier", something you'll learn more about later
+pub fn hello() -> &'static str {
+    "Hello, World!"
+}

rust/hello-world/tests/hello-world.rs

@@ -0,0 +1,4 @@
+#[test]
+fn hello_world() {
+    assert_eq!("Hello, World!", hello_world::hello());
+}

rust/reverse-string/.exercism/config.json

@@ -0,0 +1,38 @@
+{
+  "authors": [
+    "coriolinus"
+  ],
+  "contributors": [
+    "cbzehner",
+    "ccouzens",
+    "cwhakes",
+    "efx",
+    "ErikSchierboom",
+    "hunger",
+    "lutostag",
+    "ocstl",
+    "PaulT89",
+    "petertseng",
+    "rofrol",
+    "rrredface",
+    "stringparser",
+    "TheDarkula",
+    "xakon",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/reverse-string.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Reverse a given string.",
+  "source": "Introductory challenge to reverse an input string",
+  "source_url": "https://medium.freecodecamp.org/how-to-reverse-a-string-in-javascript-in-3-different-ways-75e4763c68cb"
+}

rust/reverse-string/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"rust","exercise":"reverse-string","id":"aeec5dd024f94c60b89e66907f4e90b9","url":"https://exercism.org/tracks/rust/exercises/reverse-string","handle":"Chomp1295","is_requester":true,"auto_approve":false}

rust/reverse-string/.gitignore

@@ -0,0 +1,8 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+**/*.rs.bk
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
+Cargo.lock

rust/reverse-string/Cargo.toml

@@ -0,0 +1,9 @@
+[dependencies]
+
+[features]
+grapheme = []
+
+[package]
+edition = "2021"
+name = "reverse_string"
+version = "1.2.0"

rust/reverse-string/HELP.md

@@ -0,0 +1,86 @@
+# Help
+
+## Running the tests
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test.
+
+If you wish to run _only ignored_ tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+If you are using Rust 1.51 or later, you can run _all_ tests with
+
+```bash
+$ cargo test -- --include-ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored, use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the online [test documentation][rust-tests].
+
+[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/lib.rs Cargo.toml` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Rust track's documentation](https://exercism.org/docs/tracks/rust)
+- The [Rust track's programming category on the forum](https://forum.exercism.org/c/programming/rust)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Submitting the solution
+
+Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.
+
+## Feedback, Issues, Pull Requests
+
+The GitHub [track repository][github] is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide].
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[help-page]: https://exercism.org/tracks/rust/learning
+[github]: https://github.com/exercism/rust
+[contribution guide]: https://exercism.org/docs/community/contributors

rust/reverse-string/README.md

@@ -0,0 +1,65 @@
+# Reverse String
+
+Welcome to Reverse String on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Introduction
+
+Reversing strings (reading them from right to left, rather than from left to right) is a surprisingly common task in programming.
+
+For example, in bioinformatics, reversing the sequence of DNA or RNA strings is often important for various analyses, such as finding complementary strands or identifying palindromic sequences that have biological significance.
+
+## Instructions
+
+Your task is to reverse a given string.
+
+Some examples:
+
+- Turn `"stressed"` into `"desserts"`.
+- Turn `"strops"` into `"sports"`.
+- Turn `"racecar"` into `"racecar"`.
+
+## Bonus
+
+Test your function on this string: `uüu` and see what happens. Try to write a function that properly
+reverses this string. Hint: grapheme clusters
+
+To get the bonus test to run, remove the ignore flag (`#[ignore]`) from the
+last test, and execute the tests with:
+
+```bash
+$ cargo test --features grapheme
+```
+
+You will need to use external libraries (a `crate` in rust lingo) for the bonus task. A good place to look for those is [crates.io](https://crates.io/), the official repository of crates.
+
+[Check the documentation](https://doc.rust-lang.org/cargo/guide/dependencies.html) for instructions on how to use external crates in your projects.
+
+## Source
+
+### Created by
+
+- @coriolinus
+
+### Contributed to by
+
+- @cbzehner
+- @ccouzens
+- @cwhakes
+- @efx
+- @ErikSchierboom
+- @hunger
+- @lutostag
+- @ocstl
+- @PaulT89
+- @petertseng
+- @rofrol
+- @rrredface
+- @stringparser
+- @TheDarkula
+- @xakon
+- @ZapAnton
+
+### Based on
+
+Introductory challenge to reverse an input string - https://medium.freecodecamp.org/how-to-reverse-a-string-in-javascript-in-3-different-ways-75e4763c68cb

rust/reverse-string/src/lib.rs

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+pub fn reverse(input: &str) -> String {
+    input.chars().rev().collect()
+}

rust/reverse-string/tests/reverse-string.rs

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+use reverse_string::*;
+
+#[test]
+fn an_empty_string() {
+    let input = "";
+    let output = reverse(input);
+    let expected = "";
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn a_word() {
+    let input = "robot";
+    let output = reverse(input);
+    let expected = "tobor";
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn a_capitalized_word() {
+    let input = "Ramen";
+    let output = reverse(input);
+    let expected = "nemaR";
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn a_sentence_with_punctuation() {
+    let input = "I'm hungry!";
+    let output = reverse(input);
+    let expected = "!yrgnuh m'I";
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn a_palindrome() {
+    let input = "racecar";
+    let output = reverse(input);
+    let expected = "racecar";
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn an_even_sized_word() {
+    let input = "drawer";
+    let output = reverse(input);
+    let expected = "reward";
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn wide_characters() {
+    let input = "子猫";
+    let output = reverse(input);
+    let expected = "猫子";
+    assert_eq!(output, expected);
+}
+
+#[test]
+#[ignore]
+#[cfg(feature = "grapheme")]
+fn grapheme_cluster_with_pre_combined_form() {
+    let input = "Würstchenstand";
+    let output = reverse(input);
+    let expected = "dnatsnehctsrüW";
+    assert_eq!(output, expected);
+}
+
+#[test]
+#[ignore]
+#[cfg(feature = "grapheme")]
+fn grapheme_clusters() {
+    let input = "ผู้เขียนโปรแกรม";
+    let output = reverse(input);
+    let expected = "มรกแรปโนยขีเผู้";
+    assert_eq!(output, expected);
+}