First, we’ll look at the summary comments.

“Summary” comments

# Summary: Explain how the current Ruby version is set

Running rbenv version-origin --help returns:

$ rbenv version-origin --help

Usage: rbenv version-origin

Explain how the current Ruby version is set

So this command doesn’t take any arguments. When I run it in my terminal, I get:

 $ rbenv version-origin

/Users/myusername/.rbenv/version

And when I run it in a directory with a .ruby-version file, I get:

$ rbenv version-origin

/Users/myusername/Workspace/OpenSource/impostorsguides.github.io/.ruby-version

So rbenv version-origin returns the source file where the current Ruby version is set.

Next, the tests.

Tests

Setup

After the bats shebang and the loading of test_helper, the first block of code is:

setup() {
  mkdir -p "$RBENV_TEST_DIR"
  cd "$RBENV_TEST_DIR"
}

We’ve seen this setup helper function before. It creates and navigates into the temporary test directory that we use to create our test data, directories, etc.

Having a dedicated directory in which to run our spec ensures that we have a sandbox to take whatever actions our test requires (for example, create fake Ruby version files) and subsequently blow away those actions later.

When no version file exists, global or otherwise

Our first test is:

@test "reports global file even if it doesn't exist" {
  assert [ ! -e "${RBENV_ROOT}/version" ]
  run rbenv-version-origin
  assert_success "${RBENV_ROOT}/version"
}

• This test starts with a sanity check to ensure that RBENV’s global “version” file does not exist.
• It then runs the version-origin command.
• Lastly, it asserts that this non-existent global “version” file’s path is returned anyway.

As we discovered when reading the command for rbenv version-file, the goal of returning the origin is to tell the user where the Ruby version is expected to be set, not where it is being set. That’s why this command returns the global filepath “even if it doesn’t exist”.

When the global version file exists

Next test:

@test "detects global file" {
  mkdir -p "$RBENV_ROOT"
  touch "${RBENV_ROOT}/version"
  run rbenv-version-origin
  assert_success "${RBENV_ROOT}/version"
}

This test creates the global “version” file in its expected location, then runs the version-origin command and asserts that it completed successfully, with the global version file as its output.

When the RBENV_VERSION variable is set

Next test:

@test "detects RBENV_VERSION" {
  RBENV_VERSION=1 run rbenv-version-origin
  assert_success "RBENV_VERSION environment variable"
}

This test asserts that, when we pass the RBENV_VERSION env var to the version-origin command, the command runs successfully and prints the string “RBENV_VERSION environment variable” to STDOUT.

When a .ruby-version file exists

Next test:

@test "detects local file" {
  echo "system" > .ruby-version
  run rbenv-version-origin
  assert_success "${PWD}/.ruby-version"
}

This test creates a local Ruby version file, and specifies that the version-origin command runs successfully with that local version file path as its output.

When a version-origin plugin exists

Next test:

@test "reports from hook" {
  create_hook version-origin test.bash <<<"RBENV_VERSION_ORIGIN=plugin"

  RBENV_VERSION=1 run rbenv-version-origin
  assert_success "plugin"
}

This test creates a hook for the version-origin command named test.bash, which contains code to overwrite the value of the RBENV_VERSION_ORIGIN env var to the string “plugin”.

We then run the version-origin command with a different value of RBENV_VERSION, and assert that the command used the value from the hook, not the value from the passed-in env var.

When the user overrides IFS

Next test:

@test "carries original IFS within hooks" {
  create_hook version-origin hello.bash <<SH
hellos=(\$(printf "hello\\tugly world\\nagain"))
echo HELLO="\$(printf ":%s" "\${hellos[@]}")"
SH

  export RBENV_VERSION=system
  IFS=$' \t\n' run rbenv-version-origin env
  assert_success
  assert_line "HELLO=:hello:ugly:world:again"
}

This test is similar to one we saw in the previous file’s test suite.

• We create a hook which depends on the IFS (i.e. internal field separator) env var being set to contain certain characters. These characters are the tab, whitespace, and newline characters.
  • The hook first creates an array of strings containing these characters.
  • It then prints a 2nd string which uses these characters as delimiters to split that single string into an array of strings.
• Next we set RBENV_VERSION to equal the string system.
• Next, we run the version-origin command, making sure to set IFS to contain the same characters as those we use as delimiters in our hook (tab, space, and newline).
• Finally, we assert that the command exited successfully and that the IFS characters that we set were, in fact, used to delimit the single string into an array of strings.

Copypasta error?

It looks like we’re passing an argument (i.e. the string “env”) to version-origin in this test. I’m not sure what that is. The argument doesn’t appear to be used anywhere, nor does “$1” appear anywhere in the command itself.

I took a look at the PR which introduced this line of code, and it looks like it might have been a copy-paste error, since the previous implementation of the test did not include an argument to the invocation of the command.

When the user attempts to pass the RBENV_VERSION_ORIGIN var

Last test:

@test "doesn't inherit RBENV_VERSION_ORIGIN from environment" {
  RBENV_VERSION_ORIGIN=ignored run rbenv-version-origin
  assert_success "${RBENV_ROOT}/version"
}

This test just asserts that the version-origin command ignores any value of RBENV_VERSION_ORIGIN that’s passed in via an environment variable from the caller.

That’s it for specs, now onto the code:

Code

Let’s get the usual suspects out of the way first:

set -e
[ -n "$RBENV_DEBUG" ] && set -x

• set -e to exit the script immediately when it encounters an error
• set -x to print output in verbose mode when the RBENV_DEBUG env var is set

Ensuring RBENV_VERSION_ORIGIN is not inherited

Next block of code:

unset RBENV_VERSION_ORIGIN

Here we explicitly unset any previously-set values for RBENV_VERSION_ORIGIN, such as those passed into the command by the caller.

This line of code was added in this PR, and there’s no mention of an issue or anything which may have prompted its addition.

Running hooks

Next block of code:

OLDIFS="$IFS"
IFS=$'\n' scripts=(`rbenv-hooks version-origin`)
IFS="$OLDIFS"
for script in "${scripts[@]}"; do
  source "$script"
done

We’ve seen this code before. It pulls the filepaths for any hooks for the version-origin command that the user has installed. It then runs source on each of those filepaths, to ensure that the hook code is executed.

Printing the origin filepath

The final block of code for this command:

if [ -n "$RBENV_VERSION_ORIGIN" ]; then
  echo "$RBENV_VERSION_ORIGIN"
elif [ -n "$RBENV_VERSION" ]; then
  echo "RBENV_VERSION environment variable"
else
  rbenv-version-file
fi

The only place where we could be getting our RBENV_VERSION_ORIGIN value from is a hook that was just source‘ed. That’s because:

• We explicitly unset RBENV_VERSION_ORIGIN at the top of the file, and
• We didn’t subsequently set it ourselves.

If that’s indeed what happened, we echo that value to stdout.

Otherwise, if we have a non-empty value for RBENV_VERSION (either from the caller of version-origin or from a hook file), we print the string “RBENV_VERSION environment variable” to STDOUT.

If neither of those are true, we print the output of the version-file command that we examined earlier.

That’s a wrap for this command. On to the next one.