Refactor tests

[petrduda]

• stop calling static methods in tests as non-static
• use assertSame() where assertEquals() is not explicitly needed
• use assertCount() after assertContains() for array comparison
• add missing Assert::fail() in try+catch blocks when expecting exceptions
• unify Assert::fail() message
• replace Consistence\TestCase::ok() with expectNotToPerformAssertions()
• use try+catch+fail when expecting exceptions with properties
• rename data providers to singular where applicable
• use DataProvider suffix for data providers
• change data provider return type from array to Generator
• declare data provider values on separate lines
• isolate data provider cases using Closures
• name data provider values
• name data provider cases
• extract multiple cases from test methods to data providers
• remove unnecessary private methods for creating mocks

Non-resolvable comment.