test: add tests to `ndarray/base/map`

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Description

What is the purpose of this pull request?

This pull request:

• Adds tests to ndarray/base/map for 100% coverage.

Related Issues

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This pull request:

• none

Questions

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No.

Other

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No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• [x] Read, understood, and followed the contributing guidelines.

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