Execute the following command in your exercise directory to run the tests:
To run the tests on every file save, run this command instead:
stack test --file-watch
If you get an error message like this...
No .cabal file found in directory
You are probably running an old stack version and need to upgrade it.
Otherwise, if you get an error message like this...
No compiler found, expected minor version match with... Try running "stack setup" to install the correct GHC...
Just do as it says and it will download and install the correct compiler version:
Solving the exercise
A solution to an exercise is a Haskell module. The module's name is defined in an import statement in the test suite, usually at the beginning:
import Test.Hspec (Spec, describe, it, shouldBe) import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith) import ModuleName (someFunc) main :: IO () main ...
In this example, the test file imports, in line 4, a module named
ModuleName, that exports a function named
someFunc. This means you have
to create a file named
ModuleName.hs that would be something like this:
module ModuleName (someFunc) where someFunc :: ... someFunc ...
You'll a find a file with this name already in place in
which you can use as a starting point for your solution.
Just keep in mind that this stub is there just for you to get started. Feel free to change it completely if you think it is the right thing to do.
If you want to use some packages to write a more elegant solution, just
add the packages to your solution's dependencies in
library: exposed-modules: ModuleName source-dirs: src dependencies: - foo - bar
If you want to play with your solution in GHCi, just run the command:
It's highly recommended that you run
hlint on your solution to see if it
catches something you are missing:
You don't have to accept all the suggestions given by
hlint, but usually
they will help you learn how to write beautiful, idiomatic Haskell code.