Merge nested classes for reports

[Sergey Shanshin]

When generating HTML reports and during verification, any nested classes are analyzed and displayed separately.
From the point of view of Kotlin code, this is not entirely correct, because these class-files are features of the JVM compiler implementation and do not reflect the real coverage of the Kotlin class.

It is necessary to merge coverage for the following nested classes:

• companion object
• lambda
• anonymous object
• local class

Example:

class NestedExample {
    companion object {
        // companion
    }

    private fun functionHandler(f: () -> String) {
        println("result ${f()}")
    }

    fun handle() {
        // local class
        class LocalClass { }

        // lambda
        functionHandler {
            "function"
        }

        // anonymous object
        object: Function<String> {
            override fun toString(): String = "Hi"
        }
    }
}

the coverage is evaluated separately for all classes, e.g.:

NestedExample line coverage: ..%
NestedExample$Companion line coverage: ..%
NestedExample$handle$1 line coverage: ..%
NestedExample$handle$2 line coverage: ..%
NestedExample$handle$LocalClass line coverage: ..%

Expected:

NestedExample line coverage: ..%

Important!
At the same time, regular nested classes and inner classes should continue to be counted separately:

class Nested2Example {
    class Foo {
    }

    inner class Bar {
    }
}

should give

Nested2Example line coverage: ..%
Nested2Example$Bar line coverage: ..%
Nested2Example$Foo line coverage: ..%

[Maksim Zuev]

@shanshin Do you mean only HTML report?

[Sergey Shanshin]

@zuevmaxim
No, HTML and verification.