Added more information to error when drive cycle starts at t>0

[R-Yash]

Description

When a drive cycle starts at t>0, the current error thrown seems confusing. The changes made gives drive cycle a name and throws relevant exception when t>0. The documentation is changed accordingly to reflect this fact

Fixes #3612

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[brosaplanella]

Just a small comment, but looks good overall. Can you also please add a line to the CHANGELOG?

[kratman]

@R-Yash I hope you don't mind, but I synced with develop so it would be ready for merging

[R-Yash]

@kratman Thanks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2f4a928) 99.59% compared to head (21c460f) 99.59%.
Report is 3 commits behind head on develop.

❗ Current head 21c460f differs from pull request most recent head c13f153. Consider uploading reports for the commit c13f153 to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3756   +/-   ##
========================================
  Coverage    99.59%   99.59%           
========================================
  Files          258      258           
  Lines        20823    20827    +4     
========================================
+ Hits         20738    20742    +4     
  Misses          85       85           

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[kratman]

@R-Yash Can you add a test to cover that exception?

[R-Yash]

@kratman How do I do that? I am a bit new to testcases.

[kratman]

You need to make a test that calls the function where the error is located, and passes in a time that is not zero. You can look at existing tests for that function to see if there is something you can adapt

[R-Yash]

@kratman
Can I modify this existing function ?

def test_start_times(self):
        # Test start_times
        step = pybamm.step._Step(
            "current", 1, duration=3600, start_time=datetime(2020, 1, 1, 0, 0, 0)
        )
        self.assertEqual(step.start_time, datetime(2020, 1, 1, 0, 0, 0))

        # Test bad start_times
        with self.assertRaisesRegex(TypeError, "`start_time` should be"):
            pybamm.step._Step("current", 1, duration=3600, start_time="bad start_time")

[kratman]

@kratman
Can I modify this existing function ?

def test_start_times(self):
        # Test start_times
        step = pybamm.step._Step(
            "current", 1, duration=3600, start_time=datetime(2020, 1, 1, 0, 0, 0)
        )
        self.assertEqual(step.start_time, datetime(2020, 1, 1, 0, 0, 0))

        # Test bad start_times
        with self.assertRaisesRegex(TypeError, "`start_time` should be"):
            pybamm.step._Step("current", 1, duration=3600, start_time="bad start_time")

Usually it is good to write a new test. A test like a function should have a single purpose. In this case you just want to test that an error is thrown. It will probably require a "with" statement looking for the thrown exception.

If you are really stuck then we can discuss on slack, but I recommend you give it a shot on your own first

[R-Yash]

@kratman I have added a test. Please take a look

[kratman]

Seems good as long as the tests pass

[arjxn-py]

Thanks @R-Yash Looks good, Just a small changelog suggestion.
Also waiting on tests before merging.