Add prepend function and tests

[tanhakabir]

Hey @cyjake 👋

I'm from the VS Code team and I was working on this issue: microsoft/vscode-remote-release#4592 when I realized I needed a prepend function from your library and rather than hacking prepend myself in the extension I wanted to contribute. I followed what you did in the append function and added a prepend function along with the same set of tests you had for append.

One part I wasn't completely certain about but I assumed the behavior of is when you have a config that is something like this:

Host test

Host test2
    Hostname google.com

and you prepend:

config.prepend({
      HostName: 'example.com',
      User: 'brian'
    })

I assumed the result should add the fields to the first config from the old config.

Host test
    Hostname example.com
    User brian

Host test2
    Hostname google.com

[tanhakabir]

Added flag to enable prepending below Include directives as well. To support the scenarios described in microsoft/vscode-remote-release#4592 (comment)

[cyjake]

@tanhakabir Thanks for the pr! About the question in the pr description, in my first thought the expected result should be:

HostName example.com
User brian

Host test

Host test2
    HostName google.com

This result doesn't make any sense because it shadows Host test2 section, but I think we should keep prepend() simple. For example, if we prepend:

config.prepend({
  IdentityFile: '~/.ssh/id_rsa',
})

I'd expect the result to be:

# expected
IdentityFile ~/.ssh/id_rsa

Host test

Host test2
  HostName google.com

rather than:

Host test
  IdentityFile ~/.ssh/id_rsa

Host test2
  HostName google.com

[cyjake]

Oh, about the flag to change the prepend offset, can you change it to something like beforeFirstSection? For example, if I were to prepend a new section to following config:

IdentityFile ~/.ssh/id_rsa

Host test2
  HostName google.com

I can turn on the flag as well to get results like:

IdentityFile ~/.ssh/id_rsa

Host newlyAdded
  HostName newly.added

Host test2
  HostName google.com

If the flag is on but no section were found, just append the object to the end of the config.

[cyjake]

btw, I've updated master branch to see if we can trigger CI on pull request. Please rebase master before pushing branch.

[tanhakabir]

@cyjake thanks for your feedback! Made the appropriate changes!

[tanhakabir]

@cyjake I got a notification for a comment from you but I don't see anything. Just checking in to see if I missed anything?

[cyjake]

@tanhakabir yeah I made a comment without noticing I misunderstood the context.

[cyjake]

v4.1.0 released