command: add tests for container diff and rename

[Stavrospanakakis]

- What I did
This commit adds tests for the commands docker diff and docker rename. Also, it creates the mock methods of the docker client ContainerDiff and ContainerRename so they can be used in the tests.

For docker diff, it covers the cases that:

• the command runs successfully
• the client returns an error
• the container id is empty

For docker rename, it covers the cases that:

• the command runs successfully
• the container old name is empty
• the container new name is empty
• the client returns an error

- How I did it
I read all the test cases developed in cli/command/container directory and did the same for diff.go and
rename.go using a fakeClient and mocking the client ContainerDiff and ContainerRename methods.

- How to verify it
Run: make test

- Description for the changelog

Add tests for container diff and rename commands

- A picture of a cute animal (not mandatory but encouraged)

[laurazard]

Thanks for the contribution! Left a couple of nits to make the tests a little tidier, but overall LGTM

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.92%. Comparing base (baa7a9f) to head (46b360b).
Report is 41 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5467      +/-   ##
==========================================
+ Coverage   59.74%   59.92%   +0.17%     
==========================================
  Files         345      345              
  Lines       23431    23431              
==========================================
+ Hits        13999    14040      +41     
+ Misses       8458     8417      -41     
  Partials      974      974              

[thaJeztah]

thanks for contributing! I left comments/ suggestions inline; let me know what you think

[Stavrospanakakis]

@thaJeztah @laurazard Thank you for the code review:) I committed the suggested changes from GitHub UI and will now work on the code review comments. When this pull request is ready after all the required changes, I will rebase and sign to match the Contribution guidelines.

[laurazard]

LGTM

[Stavrospanakakis]

@laurazard @thaJeztah I added all the requested changes and squashed the git commits.

[laurazard]

@thaJeztah this LGTY?

[Stavrospanakakis]

@laurazard @thaJeztah I renamed containerId to containerID because the CI failed with this error:

#16 [lint 4/4] RUN --mount=type=bind,target=.     --mount=type=cache,target=/root/.cache         golangci-lint run
#16 63.82 cli/command/container/diff_test.go:88:2: ST1003: var containerId should be containerID (stylecheck)
#16 63.82 	containerId := ""
#16 63.82 	^
#16 ERROR: process "/bin/sh -c golangci-lint run" did not complete successfully: exit code: 1
------
 > [lint 4/4] RUN --mount=type=bind,target=.     --mount=type=cache,target=/root/.cache         golangci-lint run:
63.82 cli/command/container/diff_test.go:88:2: ST1003: var containerId should be containerID (stylecheck)
63.82 	containerId := ""
63.82 	^

[thaJeztah]

LGTM!

sorry for the delay; I somehow forgot about this one 🙈

[thaJeztah]

Thanks for contributing!!