Provides an implicit conversion that adds should methods to String to support the syntax of FlatSpec, WordSpec, fixture.FlatSpec, and fixture.WordSpec.

For example, this trait enables syntax such as the following test registration in FlatSpec and fixture.FlatSpec:

"A Stack (when empty)" should "be empty" in { ... }
                       ^

It also enables syntax such as the following shared test registration in FlatSpec and fixture.FlatSpec:

"A Stack (with one item)" should behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
                          ^

In addition, it supports the registration of subject descriptions in WordSpec and fixture.WordSpec, such as:

"A Stack (when empty)" should { ...
                       ^

And finally, it also supportds the registration of subject descriptions with after words in WordSpec and fixture.WordSpec. For example:

def provide = afterWord("provide")

"The ScalaTest Matchers DSL" should provide {
                             ^

The reason this implicit conversion is provided in a separate trait, instead of being provided directly in FlatSpec, WordSpec, fixture.FlatSpec, and fixture.WordSpec, is because an implicit conversion provided directly would conflict with the implicit conversion that provides should methods on String in the Matchers trait. By contrast, there is no conflict with the separate ShouldVerb trait approach, because:

• FlatSpec, WordSpec, fixture.FlatSpec, and fixture.WordSpec mix in ShouldVerb directly, and
• Matchers extends ShouldVerb, overriding the convertToStringShouldWrapper implicit conversion function.

So whether or not a FlatSpec, WordSpec, fixture.FlatSpec, or fixture.WordSpec mixes in Matchers, there will only be one implicit conversion in scope that adds should methods to Strings.

Also, because the class of the result of the overriding convertToStringShouldWrapper implicit conversion method provided in Matchers extends this trait's StringShouldWrapperForVerb class, the four uses of should provided here are still available. These four should are in fact available to any class that mixes in Matchers, but each takes an implicit parameter that is provided only in FlatSpec and fixture.FlatSpec, or WordSpec and fixture.WordSpec.