[Java8] Add lambda parameter type annotations

[rasklaad]

Details

• @DocStringType lambda implementation
• @ParameterType lambda implementation
• @DataTableType lambda inplementation
• ParameterType with multiple capture groups
• Javadocs

Motivation and Context

Closes: #1764

How Has This Been Tested?

• docstring tests
• parametertype tests
• datatable type tests

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist:

• I've added tests for my code.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[rasklaad]

I am kinda stuck with DataTableType implementation, can't get lambda method return type, to register it with LambdaGlueRegistry.
There is a test which represent this feature:

Scenario: define data table type by lambda
    Given data table, defined with lambda
      |name  | surname       | famousBook          |
      |Fedor | Dostoevsky    |Crime and Punishment |

DataTableType((Map<String, String> entry) -> {
            return new Author(entry.get("name"), entry.get("surname"), entry.get("famousBook"));
        });

Given("data table, defined with lambda", (Author author) -> {
            assertThat(author.name, equalTo("Fedor"));
            assertThat(author.surname, equalTo("Dostoevsky"));
            assertThat(author.famousBook, equalTo("Crime and Punishment"));
        });

Also, I still don't know how to implement ParameterType with multiple capture groups, without creating a lot of functional interfaces with different amount of String arguments.
I mean something like

class ParameterTypeDefinitionBody1<T> {
    T accept(String arg) throws Throwable;
}
class ParameterTypeDefinitionBody2<T> {
    T accept(String arg1, String arg2) throws Throwable;
}
class ParameterTypeDefinitionBody3<T> {
    T accept(String arg1, String arg2, String arg3) throws Throwable;
}

etc

[mpkorstanje]

can't get lambda method return type, to register it with LambdaGlueRegistry.

You can't get at the return type from Method.getGenericReturnType because DataTableDefinitionBody<T> is generic. So the class only knows that it has a generic T type variable.

However if you have an instance of that class you can get resolved types by using the type-tools dependency with TypeResolver.resolveRawArguments.resolveRawArguments(instance, instance.getClass()). You can find an example of this in Java8StepDefinition.

Internally it looks into the constant types pool which is a JVM implementation detail but currently also the only way to provide this functionality.

Also, I still don't know how to implement ParameterType with multiple capture groups, without creating a lot of functional interfaces with different amount of String arguments.

There is no other way in Java. Best thing you can do is provide up to 9 parameters as we've done in StepdefBody.

[timtebeek]

Work continued on #1782 ; Aside from merging master, here are my changes isolated from @rasklaad :
edb0b77...lambda-type-annotations-continued
So mostly changing Java8ParameterTypeDefinition to function as CaptureGroupTransformer for String[] arguments, to support the additional parameter types with up to 9 arguments. Also: JavaDocs + tests.

[coveralls]

Coverage increased (+0.01%) to 87.177% when pulling 0dd6ffd on lambda-type-annotations into 669dd85 on master.

[mpkorstanje]

Cheers! I've merged both PR's so I can discuss them as a whole.

[timtebeek]

Addressed a few of the comments already; don't think I'll find time over the next few days to fix the remaining issues.. Anyone welcome to pick those up.

[mpkorstanje]

Whoo all done! Thanks @rasklaad and @timtebeek! Now I've got to update the release notes again! 😆

[rasklaad]

@timtebeek Thank you for the participation

[timtebeek]

@rasklaad No problem at all; glad to help, and thanks for the final push to finish the work! :)