This is part five of a series on how to approach bash programming in a way that’s safer and more structured than your basic script.

See part 1 if you want to catch the series from the start.

Last time, we created a failing test. We’ll work on making it work now, but I’m going to jump straight to the structure that a project with tests should take.

The project will be a hello, world! script, so let’s start with:

mkdir hello-world
cd hello-world
mkdir bin
mkdir shpec
echo '#!/usr/bin/env bash' >bin/hello-world
echo 'hello_world () { :;}' >>bin/hello-world
chmod 775 bin/hello-world

The hello_world function exists, but does nothing.

Move hello-world_shpec.bash to the shpec directory.

Open hello-world_shpec.bash in an editor and add the following to the beginning:

source "$(dirname -- "$(readlink --canonicalize -- "$BASH_SOURCE")")"/../bin/hello-world

That finds the true location of the hello-world_shpec.bash via readlink, then trims off the filename from the path. It then adds the relative path to our hello-world source file.

Note that on Mac, you’ll need to install GNU readlink via homebrew, then use greadlink instead of the readlink above.

Shpec now outputs the following:

> shpec shpec/hello-world_shpec.bash
hello_world
  echos 'hello, world!'
  (Expected [hello, world!] to equal [])
1 examples, 1 failures
0m0.004s 0m0.000s
0m0.000s 0m0.000s

Still failing. Excellent!

At this point, all we need to do is update the hello_world function:

#!/usr/bin/env bash

hello_world () {
  echo "hello, world!"
}

Shpec’s output:

> shpec shpec/hello-world_shpec.bash
hello_world
  echos 'hello, world!'
1 examples, 0 failures
0m0.000s 0m0.000s
0m0.000s 0m0.000s

Success! Excellent!

Continue with part 6 - outline script