vim-vspec is a testing framework for Vim script. It consists of:

• Utilities to run tests in an isolated Vim process,
• A testing framework to write tests in a format which resembles RSpec, and
• Additional syntax/indent files for Vim script to write tests.

A typical test script written with vim-vspec looks like as follows:

runtime plugin/MyGitUtilities.vim
describe 'GetGitBranchName()'
  before
    call delete('tmp/test', 'rf')
    call mkdir('tmp/test', 'p')
    cd tmp/test
  end
  after
    cd -
  end
  context 'in a non-Git directory'
    it 'returns "-"'
      Expect GetGitBranchName('.') ==# '-'
    end
  end
  context 'in a Git repository'
    before
      !git init && touch foo && git add foo && git commit -m 'Initial commit'
    end
    it 'returns the current branch'
      Expect GetGitBranchName('.') ==# 'master'
    end
    it 'detects detached HEAD state'
      !git checkout master~0
      Expect GetGitBranchName('.') ==# 'master~0'
    end
  end
end

Typical ways to run tests are as follows:

# Run tests in a specific file.
# The current directory is injected into &rutimepath before running tests.
$PATH_TO_VSPEC/bin/prove-vspec -d $PWD t/branch.vim
# Like the above, but run all tests in all files under the `t` directory.
$PATH_TO_VSPEC/bin/prove-vspec -d $PWD t/
# Like the above, but you may omit `t` because it's the default target.
$PATH_TO_VSPEC/bin/prove-vspec -d $PWD

Its output looks like as follows:

t/branch.vim .. ok
All tests successful.
Files=1, Tests=3,  1 wallclock secs ( 0.02 usr  0.00 sys +  0.07 cusr  0.11 csys =  0.20 CPU)
Result: PASS

prove-vspec runs a test script in an isolated Vim process, and show a summary like the above. User-specific configurations, like ~/.vimrc and files in ~/.vim, will never be used to avoid unintentional dependencies.

For proper testing, you have to set up environment to run tests. Suppose that you want to test a plugin which depends on some other plugins, you have to:

• Install such dependencies to somewhere, and
• Specify where the dependencies are installed to run tests.

These steps are tedious to do by hand. It is recommended to use vim-flavor to automate such tasks. See How to set up GitHub Actios as CI for Vim plugin development for details.

• A tutorial to use vim-vspec by Vimcasts.org
• Introduce unit testing to Vim plugin development with vim-vspec
• How to set up GitHub Actios as CI for Vim plugin development