TestSandbox random dir generation

[virkt25]

Description / Steps to reproduce / Feature proposal

Current TestSandbox uses the same folder the user provides for tests. If a file put in the sandbox is required, it gets cached by it. A workaround for clearing the cache was introduced in #1391 but as per the comments, #1391 (comment), decaching has it's own challenges.

Current Behavior

• Before PR fix(testlab): decache files in TestSandbox when resetting it #1391, files get cached -- can break tests. Issues with multiple tests running in parallel.
• After PR fix(testlab): decache files in TestSandbox when resetting it #1391, files are decached but not a robust implementation. Multiple tests in parallel still an issue.

Expected Behavior

TestSandbox should create a random folder in the given path (can be considered a basepath). When the sandbox is reset, instead of decaching -- we delete the old random folder and create a new one for the user. Similar behaviour as used in loopback-boot, see comment #1391 (comment)

Acceptance Criteria

• Given a path for a TestSandbox (like present) - the instance should create a random folder inside that for the test
• When the TestSandbox instance is reset, the randomly generated folder should be deleted. A new random folder should be generated -- prevent issues with caching and parallel tests.
• Provide convenience methods on TestSandbox instance such as sandbox.resolve(), sandbox.existsFile(), sandbox.existsDir(), etc. -- to make working with sandbox easier as we now have random folders being generated -- this should be an abstraction from the user of TestSandbox.
• Tests
• Docs (TestSandbox is currently lacking documentation).

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[jannyHou]

@dhmlau could you label this issue properly? Thanks. It's estimated.

[dhmlau]

@jannyHou @virkt25 , what's the impact of not fixing it (or deferring it after DP3)?

[virkt25]

For now the issue has a temporary fix. This doesn't need to be a part of DP3 IMO.

[stale]

This issue has been marked stale because it has not seen activity within six months. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository. This issue will be closed within 30 days of being stale.

[stale]

This issue has been closed due to continued inactivity. Thank you for your understanding. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository.