Enumerable.MaxBy should describe behavior of throw Sequence contains no elements InvalidOperationException for empty primitive type enumerables

[gewarren]

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Issue moved from MicrosoftDocs/feedback#3721

• Please respond to @Smoovsky.

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From @Smoovsky on Thursday, December 2, 2021 5:39:28 AM

Describe the bug
I noticed new Sytem.Linq.Enumrable.MaxBy method provided in .NET 6.0:
doc
The documentation states two types of exception ArgumentException and ArgumentNullException to be expected.
But InvalidOperationException may also be thrown for empty primitive type enumerables, see the example below.

To Reproduce
Steps to reproduce the behavior:
Snippet:

void Main()
{
	var test1 = new Test[] { }.MaxBy(x => x.MyProperty); // no problem
	var test2 = new Test[] { new Test { MyProperty = 1 }, new Test { MyProperty = 1 } }.MaxBy(x => x.MyProperty); // no problem
	var test3 = new int[] { }.MaxBy(x => x); // exception here
}

public class Test
{ 
	public int MyProperty { get; set; }
}

Run result:

[gewarren]

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Issue moved from MicrosoftDocs/feedback#3721

• Please respond to @WELCOME[bot].

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From @WELCOME[bot] on Thursday, December 2, 2021 5:39:30 AM

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Issue Details

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---

Issue moved from MicrosoftDocs/feedback#3721

• Please respond to @Smoovsky.

---

From @Smoovsky on Thursday, December 2, 2021 5:39:28 AM

Describe the bug
I noticed new Sytem.Linq.Enumrable.MaxBy method provided in .NET 6.0:
doc
The documentation states two types of exception ArgumentException and ArgumentNullException to be expected.
But InvalidOperationException may also be thrown for empty primitive type enumerables, see the example below.

To Reproduce
Steps to reproduce the behavior:
Snippet:

void Main()
{
	var test1 = new Test[] { }.MaxBy(x => x.MyProperty); // no problem
	var test2 = new Test[] { new Test { MyProperty = 1 }, new Test { MyProperty = 1 } }.MaxBy(x => x.MyProperty); // no problem
	var test3 = new int[] { }.MaxBy(x => x); // exception here
}

public class Test
{ 
	public int MyProperty { get; set; }
}

Run result:

Author:	gewarren
Assignees:	-
Labels:	Pri3, area-System.Linq, :watch: Not Triaged
Milestone:	-

[eiriktsarpalis]

Yes, we should be documenting that exception. Note that this is also missing from the Max and Min and MinBy methods.

[jamesHargreaves12]

@eiriktsarpalis I was just tripped up by this issue as well and wanted to check if there had been any progress made?

I think the issue is not only that the docs are missing documentation of the Exception but also that for MinBy and MaxBy the current Remarks are actually incorrect.

If TKey is a reference type and the source sequence is empty or contains only values that are null, this method returns null.

TKey should be replaced with TSource.