testsuite: new pansharpen test

[manan-T]

No description provided.

[wenzeslaus]

The test passes and but it mockes everything. Actual test is missing. Did you run i.pansharpen locally to retrieve some values to see what the current code outputs?

[echoix]

What's the difference intended between this new PR and #3757?

In both PRs, the testsuite/tests/test_pansharpen.py files are the same.

Also, what is the intended difference between the testsuite/tests/test_pansharpen.py and testsuite/test_pansharpen.py?

Finally, tests for modules like this should be (according to the current layout) located in the same subfolder as the module, in this case something like:

scripts/i.pansharpen/testsuite for gunittest-based tests.
scripts/i.pansharpen/tests for tests that can be ran by pytest.

[veroandreo]

I'd say we close both this and #3757. @manan-T is welcome to open a new PR addressing the comments.