add expectations for uppercase, lowercase, alpha and alphanumeric

[JonPurvis]

Q	A
Bug fix?	yes/no
New feature?	yes/no
Fixed tickets	N/A

Introduction

This PR adds a few more Expectations that would be useful in some projects I work with Pest on, hopefully other people will find them useful too. We have:

• toBeUppercase()
• toBeLowercase()
• toBeAlphaNumeric()
• toBeAlpha()

Usage

it('succeeds if uppercase', function () {
    expect('UPPERCASE')->toBeUppercase();
});

it('succeeds if lowercase', function () {
    expect('lowercase')->toBeLowercase();
});

it('succeeds if alpha', function () {
    expect('abc')->toBeAlpha();
});

it('succeeds if alphanumeric', function () {
    expect('abc123')->toBeAlphaNumeric();
});

it('succeeds if not uppercase', function () {
    expect('lowercase')->not->toBeUppercase();
});

it('succeeds if not lowercase', function () {
    expect('UPPERCASE')->not->toBeLowercase();
});

it('succeeds if not alpha', function () {
    expect('123')->not->toBeAlpha();
});

it('succeeds if not alphanumeric', function () {
    expect('-')->not->toBeAlphaNumeric();
});

[faissaloux]

@JonPurvis thanks for your contribution.

Can you add toBeNumeric() using ctype_digit.

Thanks.

[JonPurvis]

Thanks @faissaloux!

toBeNumeric() already exists in that class and uses assertIsNumeric().

[JonPurvis]

@fabio-ivona Would you mind approving again please? I pushed a change to fix some complains with one of the tests

Thanks! :)