Fix collection-optimized paths for Batch

[viceroypenguin]

The Batch operator contains similar problems to those addressed in issue #943/PR #946. This PR removes all collection optimizations, since they are all based on caching the collection count at initial call instead of run-time.

[atifaziz]

Good catch and thanks for submitting the PR!

Two things:

1. There are failing tests that need to be adjusted.
2. The PR removes all optimisations whereas they should have been moved into the iterator method for similar savings at iteration-time.

[viceroypenguin]

1. Oops. Wilco.
2. Will restore for now, and issue separate PR to remove them after this PR is pulled in. Discussion to be tabled until then.

[codecov]

Codecov Report

Merging #965 (5057527) into master (aefa90b) will increase coverage by 0.05%.
The diff coverage is 100.00%.

❗ Current head 5057527 differs from pull request most recent head 2d49f5a. Consider uploading reports for the commit 2d49f5a to get more accurate results

@@            Coverage Diff             @@
##           master     #965      +/-   ##
==========================================
+ Coverage   92.49%   92.55%   +0.05%     
==========================================
  Files         113      113              
  Lines        3424     3423       -1     
  Branches     1024     1020       -4     
==========================================
+ Hits         3167     3168       +1     
  Misses        192      192              
+ Partials       65       63       -2     

Impacted Files	Coverage Δ
MoreLinq/Batch.cs	98.07% <100.00%> (+3.73%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[atifaziz]

and issue separate PR to remove them after this PR is pulled in

What's the reason behind removing them at all?

[atifaziz]

Thanks for the follow-up, but I am afraid the test and the implementation don't look right. See my comments.

[viceroypenguin]

Thanks for the follow-up, but I am afraid the test and the implementation don't look right. See my comments.

Bah! Too many branches on too many projects. :)

[atifaziz]

The two could be combined into a effectively single test?

[TestCase(SourceKind.BreakingList)]
[TestCase(SourceKind.BreakingReadOnlyList)]
[TestCase(SourceKind.BreakingCollection)]
public void BatchUsesCollectionCountAtIterationTime(SourceKind kind)
{
    var list = new List<int> { 1, 2 };
    var result = list.ToSourceKind(kind, copy: false).Batch(3);

    list.Add(3);
    Assert.That(result.Consume, Throws.Nothing);

    list.Add(4);
    Assert.That(result.Consume, Throws.TypeOf<BreakException>());
}

[atifaziz]

@viceroypenguin Any chance we can merge this soon?

[atifaziz]

Thanks for this!