Improve naming conventions for test methods.

[tacosontitan]

The currently defined test methods don't clearly articulate what is actually being tested, which is critical given the indirect and sometimes rather obscure naming of the methods utilized to achieve terse code to levels that are competitive with more golf-friendly languages. Take the tests for the methods for generating ranges for example:

[Fact]
public void GR_SingleParam_Generates_Correct_Range()
{
    var count = 5;
    var result = Gr(count);
    Assert.Equal(Enumerable.Range(1, count), result);
}

For starters, this fully-underscored naming convention needlessly extends the name and adds little to no value. That can be simplified to separating the method, condition, and result; for example, the method above could be simplified to:

public void GR_SingleParam_GeneratesCorrectRange();

Additionally, the GR here isn't as useful as it could be from a maintenance perspective. Instead, let's expand the name to its more legible representation GenerateRange. While it doesn't match the actual method being tested, it helps developers maintaining the project better understand the code they're working with:

[Fact]
public void GenerateRange_SingleParameter_GeneratesCorrectRange()
{
    var count = 5;
    var result = Gr(count);
    Assert.Equal(Enumerable.Range(1, count), result);
}

This issue covers the correction of the test methods defined in:

• Generate Range Tests (tested methods)
• Filter Tests (tested methods)