Fix entrypoint parsing logic

[lalyos]

Right now the test passes even if you change the expected value. It passes if the array has 1 element.

- What I did

I was trying to understand the docker run --entrypoint parsing process, and run the test:
go test -v ./cli/command/container -run Entry and even when I changed the expected value, it still passed?!

- How to verify it

change the expected value to foo and run: go test -v ./cli/command/container -run Entry

[thaJeztah]

Nice catch! These tests were added really long ago, and could use some cleaning up in general. I suspect the != 1 was added with the intent to prevent an out of bound if the slice was empty, but indeed flipped the boolean condition; had a quick peek and it looks like this was added when this code still lived in the moby/moby repository, and was part of a bigger refactor (moby/moby#14134) so definitely overlooked in review; moby/moby@d4aec5f#diff-b669db027d2079a55de7d0b67c632c4dc70ab0e577c4de03e8557dfd9f4898d5

[thaJeztah]

Given that we already have the gotest.tools assert imported in this package (and use it for other tests in this file), we could use that for this test;

func TestParseEntryPoint(t *testing.T) {
	config, _, _, err := parseRun([]string{"--entrypoint=anything", "cmd", "img"})
	assert.NilError(t, err)
	assert.Check(t, is.DeepEqual(config.Entrypoint, []string{"anything"}))
}

[thaJeztah]

Thank you for contributing! It appears your commit message is missing a DCO sign-off,
causing the DCO check to fail.

We require all commit messages to have a Signed-off-by line with your name
and e-mail (see "Sign your work"
in the CONTRIBUTING.md in this repository), which looks something like:

Signed-off-by: YourFirsName YourLastName <yourname@example.org>

There is no need to open a new pull request, but to fix this (and make CI pass),
you need to amend the commit(s) in this pull request, and "force push" the amended
commit.

Unfortunately, it's not possible to do so through GitHub's web UI, so this needs
to be done through the git commandline.

You can find some instructions in the output of the DCO check (which can be found
in the "checks" tab on this pull request), as well as in the Moby contributing guide.

Steps to do so "roughly" come down to:

1. Set your name and e-mail in git's configuration:

   git config --global user.name "YourFirstName YourLastName"
   git config --global user.email "yourname@example.org"

   (Make sure to use your real name (not your GitHub username/handle) and e-mail)

2. Clone your fork locally

3. Check out the branch associated with this pull request

4. Sign-off and amend the existing commit(s)

   git commit --amend --no-edit --signoff

   If your pull request contains multiple commits, either squash the commits (if
   needed) or sign-off each individual commit.

5. Force push your branch to GitHub (using the --force or --force-with-lease flags) to update the pull request.

Sorry for the hassle (I wish GitHub would make this a bit easier to do), and let me know if you need help or more detailed instructions!

[thaJeztah]

Ah, sorry for the canned reply; I see there's a sign-off, but DCO-check saw the spelling of your name was different than the information in the git "author" field (Lajos vs Lalyos); it can be rather picky on that, so you may have to either change your "author" config in git, or amend the sign-off line;

Commit sha: 10a91f1, Author: Lajos Papp, Committer: Lajos Papp; Expected "Lajos Papp lalyos@yahoo.com", but got "Lalyos Papp lalyos@yahoo.com".

[lalyos]

DCO is fixed
I used your version with gotest.tools but had to change the asserted type from []string to []strslice.StrSlice

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.18%. Comparing base (f488a75) to head (e868f0f).
Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5830      +/-   ##
==========================================
+ Coverage   58.79%   59.18%   +0.38%     
==========================================
  Files         349      352       +3     
  Lines       29536    29547      +11     
==========================================
+ Hits        17367    17486     +119     
+ Misses      11186    11080     -106     
+ Partials      983      981       -2     

[thaJeztah]

Ah! Good one; forgot it was defined using that type; yeah either way (casting to []string or vice-versa should be fine in this case; I recall I recently changed some tests elsewhere because the []strslice.StrSlice was only to help with JSON marshalling.

[thaJeztah]

LGTM!

Thanks for contributing!

[lalyos]

Btw as it turned out that entrypoint is an strslice, I got the the crazy itch to check if I could give an actual array to --entrypoint using the same syntax as in Dockerfile's ENTRYPOINT

It just took 3 lines: 284534f and then you could do:

$ docker run --entrypoint '["sh","-c","echo look ma entrypoint as an array"]' alpine

look ma entrypoint as an array

I myself question if its practical at all, but I saw a couple of issues mentioning this feature.
What's your opinion, should I open a PR (with a couple of new tests: de56693)?