Add support for Scoverage (#571)

* Add initial work for ScoverageModule

* style: Move package scoverage from lib to contrib

Suggested by @lefou
> I think, it would be better to add under `mill.contrib.scoverage`.

Pull request: #571

* Initial changes to non-hardcoded scoverage version

* Using task context api to specify dataDir

Now measurement data will be written to:
PROJECT_ROOT/out/MODULE/scoverage/data/

and the html report will be written to:
PROJECT_ROOT/out/MODULE/scoverage/data/htmlReport/

* Remove wild card imports in scoverage

Also remove scoverage dependency from build.sc

* Move htmlReport into worker

Based on what I've seen in
scalalib, scalajslib, scalanativelib, playlib, and twirllib modules.

Still need to add tests

* Add basic docs + tests for scoverage

I still am working on testing the actual generation of
reports.

* Use cross-module for scoverage worker

Now we can support multiple versions of scoverage
by adding them to the crossmodule list.

Also now running the local publish script succeeds.

* Add scoverage to ci tests

* Add detailed ScoverageModule documentation

* Test scoverage dataDir

* Remove <pre> tags in scaladoc

* Add scoverage dependency in less hacky way

* Modify scoverage tests to check classpaths

* Put docs in alphabetical order

* Test classpaths for scoverage runtime

* Remove abstract def test: ScoverageTests

* Construct classloader differently

* Revert "Construct classloader differently"

This reverts commit fccf9a94cc38fb9e2be58a9ff90b00b65f339db6.

* Revert "Construct classloader differently"

Also fixes unfound error in html report

This reverts commit fccf9a94cc38fb9e2be58a9ff90b00b65f339db6.

* Fix classpath for scoverage worker

2 files changed, 113 insertions, 0 deletions

diff --git a/contrib/scoverage/test/resources/hello-world/core/src/Greet.scala b/contrib/scoverage/test/resources/hello-world/core/src/Greet.scala
new file mode 100644
index 00000000..608becc9
--- /dev/null
+++ b/contrib/scoverage/test/resources/hello-world/core/src/Greet.scala
@@ -0,0 +1,6 @@
+object Greet {
+  def greet(name: String, prefix: Option[String]): String = prefix match {
+    case Some(p) => s"Hello, ${p} ${name}!"
+    case None => s"Hello, ${name}!"
+  }
+}
diff --git a/contrib/scoverage/test/src/HelloWorldTests.scala b/contrib/scoverage/test/src/HelloWorldTests.scala
new file mode 100644
index 00000000..98a4201c
--- /dev/null
+++ b/contrib/scoverage/test/src/HelloWorldTests.scala
@@ -0,0 +1,107 @@
+package mill.contrib.scoverage
+
+import mill._
+import mill.api.Result
+import mill.scalalib._
+import mill.util.{TestEvaluator, TestUtil}
+import utest._
+import utest.framework.TestPath
+
+object HelloWorldTests extends utest.TestSuite {
+  val resourcePath = os.pwd / 'contrib / 'scoverage / 'test / 'resources / "hello-world"
+  trait HelloBase extends TestUtil.BaseModule {
+    def millSourcePath =  TestUtil.getSrcPathBase() / millOuterCtx.enclosing.split('.')
+  }
+
+  object HelloWorld extends HelloBase {
+    object core extends ScoverageModule {
+      def scalaVersion = "2.12.4"
+      def scoverageVersion = "1.3.1"
+
+      object test extends ScoverageTests {
+        override def ivyDeps = Agg(ivy"org.scalatest::scalatest:3.0.5")
+        def testFrameworks = Seq("org.scalatest.tools.Framework")
+      }
+    }
+  }
+
+  def workspaceTest[T](m: TestUtil.BaseModule, resourcePath: os.Path = resourcePath)
+                      (t: TestEvaluator => T)
+                      (implicit tp: TestPath): T = {
+    val eval = new TestEvaluator(m)
+    os.remove.all(m.millSourcePath)
+    os.remove.all(eval.outPath)
+    os.makeDir.all(m.millSourcePath / os.up)
+    os.copy(resourcePath, m.millSourcePath)
+    t(eval)
+  }
+
+  def tests: utest.Tests = utest.Tests {
+    "HelloWorld" - {
+      "core" - {
+        "scoverageVersion" - workspaceTest(HelloWorld) { eval =>
+          val Right((result, evalCount)) = eval.apply(HelloWorld.core.scoverageVersion)
+
+          assert(
+            result == "1.3.1",
+            evalCount > 0
+          )
+        }
+        "scoverage" - {
+          "ivyDeps" - workspaceTest(HelloWorld) { eval =>
+            val Right((result, evalCount)) =
+              eval.apply(HelloWorld.core.scoverage.ivyDeps)
+
+            assert(
+              result == Agg(ivy"org.scoverage::scalac-scoverage-runtime:1.3.1"),
+              evalCount > 0
+            )
+          }
+          "scalacPluginIvyDeps" - workspaceTest(HelloWorld) { eval =>
+            val Right((result, evalCount)) =
+              eval.apply(HelloWorld.core.scoverage.scalacPluginIvyDeps)
+
+            assert(
+              result == Agg(ivy"org.scoverage::scalac-scoverage-plugin:1.3.1"),
+              evalCount > 0
+            )
+          }
+          "dataDir" - workspaceTest(HelloWorld) { eval =>
+            val Right((result, evalCount)) = eval.apply(HelloWorld.core.scoverage.dataDir)
+
+            assert(
+              result.toString.endsWith("mill/target/workspace/mill/contrib/scoverage/HelloWorldTests/eval/HelloWorld/core/scoverage/dataDir/core/scoverage/data"),
+              evalCount > 0
+            )
+          }
+        }
+        "test" - {
+          "upstreamAssemblyClasspath" - workspaceTest(HelloWorld) { eval =>
+            val Right((result, evalCount)) = eval.apply(HelloWorld.core.scoverage.upstreamAssemblyClasspath)
+
+            assert(
+              result.map(_.toString).exists(_.contains("scalac-scoverage-runtime")),
+              evalCount > 0
+            )
+          }
+          "compileClasspath" - workspaceTest(HelloWorld) { eval =>
+            val Right((result, evalCount)) = eval.apply(HelloWorld.core.scoverage.compileClasspath)
+
+            assert(
+              result.map(_.toString).exists(_.contains("scalac-scoverage-runtime")),
+              evalCount > 0
+            )
+          }
+          "runClasspath" - TestUtil.disableInJava9OrAbove(workspaceTest(HelloWorld) { eval =>
+            val Right((result, evalCount)) = eval.apply(HelloWorld.core.scoverage.runClasspath)
+
+            assert(
+              result.map(_.toString).exists(_.contains("scalac-scoverage-runtime")),
+              evalCount > 0
+            )
+          })
+        }
+      }
+    }
+  }
+}