100 lines
3.8 KiB
Markdown
100 lines
3.8 KiB
Markdown
|
# Two Fer
|
||
|
|
|
||
|
|
`Two-fer` or `2-fer` is short for two for one. One for you and one for me.
|
||
|
|
|
||
|
|
```
|
||
|
|
"One for X, one for me."
|
||
|
|
```
|
||
|
|
|
||
|
|
When X is a name or "you".
|
||
|
|
|
||
|
|
If the given name is "Alice", the result should be "One for Alice, one for me."
|
||
|
|
If no name is given, the result should be "One for you, one for me."
|
||
|
|
|
||
|
|
|
||
|
|
## Test-Driven Development
|
||
|
|
|
||
|
|
As programmers mature, they eventually want to test their code.
|
||
|
|
|
||
|
|
Here at Exercism we simulate [Test-Driven
|
||
|
|
Development](http://en.wikipedia.org/wiki/Test-driven_development) (TDD), where
|
||
|
|
you write your tests before writing any functionality. The simulation comes in
|
||
|
|
the form of a pre-written test suite, which will signal that you have solved
|
||
|
|
the problem.
|
||
|
|
|
||
|
|
It will also provide you with a safety net to explore other solutions without
|
||
|
|
breaking the functionality.
|
||
|
|
|
||
|
|
### A typical TDD workflow on Exercism:
|
||
|
|
|
||
|
|
1. Run the test file and pick one test that's failing.
|
||
|
|
2. Write some code to fix the test you picked.
|
||
|
|
3. Re-run the tests to confirm the test is now passing.
|
||
|
|
4. Repeat from step 1.
|
||
|
|
5. Submit your solution (`exercism submit /path/to/file`)
|
||
|
|
|
||
|
|
## Instructions
|
||
|
|
|
||
|
|
Submissions are encouraged to be general, within reason. Having said that, it's
|
||
|
|
also important not to over-engineer a solution.
|
||
|
|
|
||
|
|
It's important to remember that the goal is to make code as expressive and
|
||
|
|
readable as we can.
|
||
|
|
|
||
|
|
Most Java exercises include multiple test cases. These cases are structured to
|
||
|
|
support a useful process known as
|
||
|
|
[test-driven development (TDD)](https://en.wikipedia.org/wiki/Test-driven_development).
|
||
|
|
TDD involves repeating a structured cycle that helps programmers build complex
|
||
|
|
functionality piece by piece rather than all at once. That cycle can be
|
||
|
|
described as follows:
|
||
|
|
|
||
|
|
1. Add a test that describes one piece of desired functionality your code is
|
||
|
|
currently missing.
|
||
|
|
2. Run the tests to verify that this newly-added test fails.
|
||
|
|
3. Update your existing code until:
|
||
|
|
- All the old tests continue to pass;
|
||
|
|
- The new test also passes.
|
||
|
|
4. [Clean up](https://en.wikipedia.org/wiki/Code_refactoring) your code, making
|
||
|
|
sure that all tests continue to pass. This typically involves renaming
|
||
|
|
variables, removing duplicated chunks of logic, removing leftover logging, etc.
|
||
|
|
5. Return to step 1 until all desired functionality has been built!
|
||
|
|
|
||
|
|
The test files in this track contain _all_ the tests your solution should pass
|
||
|
|
to be considered valid. That doesn't immediately seem to be compatible with the
|
||
|
|
cycle described above, in which tests are written one by one. However, the
|
||
|
|
tool that we use to write our tests, [JUnit](http://junit.org), provides an
|
||
|
|
[@Ignore](http://junit.sourceforge.net/javadoc/org/junit/Ignore.html)
|
||
|
|
[annotation](https://docs.oracle.com/javase/tutorial/java/annotations/) that
|
||
|
|
can be used to temporarily skip an already-written test. Using this annotation,
|
||
|
|
we make sure that the test files we deliver to you satisfy the following rules:
|
||
|
|
|
||
|
|
- The first test in any test file is _not_ skipped by default.
|
||
|
|
- All but the first test in any test file _are_ skipped by default.
|
||
|
|
|
||
|
|
This allows you to simulate the TDD cycle by following these slightly-modified
|
||
|
|
steps:
|
||
|
|
|
||
|
|
1. Run the tests to verify that _at most one_ test currently fails.
|
||
|
|
2. Update your existing code until all the non-skipped tests pass.
|
||
|
|
3. Clean up your code, making sure that all non-skipped tests continue to pass.
|
||
|
|
4. Remove the topmost `@Ignore` annotation in the test file.
|
||
|
|
5. Return to step 1 until no tests are skipped and all tests pass!
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
To run the tests:
|
||
|
|
|
||
|
|
```sh
|
||
|
|
$ gradle test
|
||
|
|
```
|
||
|
|
|
||
|
|
For more detailed info about the Java track see the [help page](http://exercism.io/languages/java).
|
||
|
|
|
||
|
|
|
||
|
|
## Source
|
||
|
|
|
||
|
|
This is an exercise to introduce users to basic programming constructs, just after hello World. [https://en.wikipedia.org/wiki/Two-fer](https://en.wikipedia.org/wiki/Two-fer)
|
||
|
|
|
||
|
|
## Submitting Incomplete Solutions
|
||
|
|
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
|