Junit & Specs2 support (#163)

* adding junit scala test running

* discovered_classes output actually redirected to file
run files currently manually built
DiscoveredTestSuite correctly parses the zip entries
JunitTest removes the @RunWith since it's not mandatory

* added discovered_classes to rjars and so removed cp hack and reusing shared runfiles

* explicitly adding the discovered_classes file to the runfiles

* removed stale comment

* changed target name so it's clear target name is not bound to class name

* explained a todo better, removed allow_files since it's included in single_file)

* split whitespace and metadata filtering

* added comment about the usage of grep in skylark

* added support for runtime deps and compile time deps

* added support for jvm_flags and multiple custom suffixes

* support patterns and not only suffixes

* added specs2 junit support

* extracted specs2 version to method

* removed comments

* removed another comment

* moved to depend on an isolated dependency

* apparently -a doesn't add untracked

* moved from unzip to jar and reformatted DiscoveredTestSuite

* added test to show junit failures are supported

* added a test to show xml files are generated

* moved from filegroup in scala.bzl to src/scala ones

* removed scalac warning

* added comment to clarify design

* moved to using bazel jar

* Trigger

* fixed formatting comments

* Revert "moved from filegroup in scala.bzl to src/scala ones"

This reverts commit 558640d.

* moved from explicitly depending on @scala to using bind

* moved from patterns to prefixes/suffixes
moved from using jar/grep to JarInputStream in JVM
added print debugging of discovered classes
changed e2e tests which check multi files to use print debugging

* removed unneeded globs

* removed unused imports

* renamed CustomPattern to CustomPrefix

* mandating at least one of prefixes/suffixes attributes be set

* erroring when no tests are discovered

* multiple prefixes test, dropped single suffix and single prefix tests since they are covered by the  test

* Fixed typo

* another typo from the script

Author: ittaiz

WORKSPACE

@@ -12,6 +12,9 @@ tut_repositories()
 load("//jmh:jmh.bzl", "jmh_repositories")
 jmh_repositories()
 
+load("//specs2:specs2_junit.bzl","specs2_junit_repositories")
+specs2_junit_repositories()
+
 # test adding a scala jar:
 maven_jar(
   name = "com_twitter__scalding_date",

junit/BUILD

@@ -0,0 +1,14 @@
+def junit_repositories():
+  native.maven_jar(
+      name = "io_bazel_rules_scala_junit_junit",
+      artifact = "junit:junit:4.12",
+      sha1 = "2973d150c0dc1fefe998f834810d68f278ea58ec",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/junit/junit', actual = '@io_bazel_rules_scala_junit_junit//jar')
+  
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_hamcrest_hamcrest_core",
+      artifact = "org.hamcrest:hamcrest-core:1.3",
+      sha1 = "42a25dc3219429f0e5d060061f71acb49bf010a0",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/hamcrest/hamcrest_core', actual = '@io_bazel_rules_scala_org_hamcrest_hamcrest_core//jar')

junit/junit.bzl

@@ -14,6 +14,7 @@
 
 """Rules for supporting the Scala language."""
 
+load("//specs2:specs2_junit.bzl", "specs2_junit_dependencies")
 _jar_filetype = FileType([".jar"])
 _java_filetype = FileType([".java"])
 _scala_filetype = FileType([".scala"])
@@ -535,8 +536,7 @@ def _scala_test_impl(ctx):
     jars = _collect_jars(deps)
     (cjars, rjars) = (jars.compiletime, jars.runtime)
     cjars += [ctx.file._scalareflect, ctx.file._scalatest, ctx.file._scalaxml]
-    rjars += [
-              ctx.outputs.jar,
+    rjars += [ctx.outputs.jar,
               ctx.file._scalalib,
               ctx.file._scalareflect,
               ctx.file._scalatest,
@@ -561,6 +561,40 @@ def _scala_test_impl(ctx):
     )
     return _scala_binary_common(ctx, cjars, rjars)
 
+def _gen_test_suite_flags_based_on_prefixes_and_suffixes(ctx, archive):
+    return struct(suite_class = "io.bazel.rulesscala.test_discovery.DiscoveredTestSuite", 
+    archiveFlag = "-Dbazel.discover.classes.archive.file.path=%s" % archive.short_path,
+    prefixesFlag = "-Dbazel.discover.classes.prefixes=%s" % ",".join(ctx.attr.prefixes),
+    suffixesFlag = "-Dbazel.discover.classes.suffixes=%s" % ",".join(ctx.attr.suffixes),
+    printFlag = "-Dbazel.discover.classes.print.discovered=%s" % ctx.attr.print_discovered_classes)
+
+def _scala_junit_test_impl(ctx):
+    if (not(ctx.attr.prefixes) and not(ctx.attr.suffixes)):
+      fail("Setting at least one of the attributes ('prefixes','suffixes') is required")
+    deps = ctx.attr.deps + [ctx.attr._suite]
+    jars = _collect_jars(deps)
+    (cjars, rjars) = (jars.compiletime, jars.runtime)
+    junit_deps = [ctx.file._junit,ctx.file._hamcrest]
+    cjars += junit_deps
+    rjars += [ctx.outputs.jar,
+              ctx.file._scalalib
+              ] + junit_deps
+    rjars += _collect_jars(ctx.attr.runtime_deps).runtime
+    test_suite = _gen_test_suite_flags_based_on_prefixes_and_suffixes(ctx, ctx.outputs.jar)
+    launcherJvmFlags = ["-ea", test_suite.archiveFlag, test_suite.prefixesFlag, test_suite.suffixesFlag, test_suite.printFlag]
+    _write_launcher(
+        ctx = ctx,
+        rjars = rjars,
+        main_class = "org.junit.runner.JUnitCore",
+        jvm_flags = launcherJvmFlags + ctx.attr.jvm_flags,
+        args = test_suite.suite_class,
+        run_before_binary = "",
+        run_after_binary = "",
+    )
+
+    return _scala_binary_common(ctx, cjars, rjars)
+
+
 _implicit_deps = {
   "_ijar": attr.label(executable=True, cfg="host", default=Label("@bazel_tools//tools/jdk:ijar"), allow_files=True),
   "_scalac": attr.label(executable=True, cfg="host", default=Label("//src/java/io/bazel/rulesscala/scalac"), allow_files=True),
@@ -687,6 +721,30 @@ exports_files([
   "lib/scala-xml_2.11-1.0.4.jar",
   "lib/scalap-2.11.8.jar",
 ])
+
+filegroup(
+    name = "scala-xml",
+    srcs = ["lib/scala-xml_2.11-1.0.4.jar"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "scala-parser-combinators",
+    srcs = ["lib/scala-parser-combinators_2.11-1.0.4.jar"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "scala-library",
+    srcs = ["lib/scala-library.jar"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "scala-reflect",
+    srcs = ["lib/scala-reflect.jar"],
+    visibility = ["//visibility:public"],
+)
 """
 
 def scala_repositories():
@@ -722,6 +780,14 @@ def scala_repositories():
     server = "scalac_deps_maven_server",
   )
 
+  native.bind(name = 'io_bazel_rules_scala/dependency/scala/scala_xml', actual = '@scala//:scala-xml')
+
+  native.bind(name = 'io_bazel_rules_scala/dependency/scala/parser_combinators', actual = '@scala//:scala-parser-combinators')
+
+  native.bind(name = 'io_bazel_rules_scala/dependency/scala/scala_library', actual = '@scala//:scala-library')
+
+  native.bind(name = 'io_bazel_rules_scala/dependency/scala/scala_reflect', actual = '@scala//:scala-reflect')
+
 def scala_export_to_java(name, exports, runtime_deps):
   jars = []
   for target in exports:
@@ -792,4 +858,26 @@ def scala_library_suite(name,
         ts.append(n)
     scala_library(name = name, deps = ts, exports = exports + ts, visibility = visibility)
 
+scala_junit_test = rule(
+  implementation=_scala_junit_test_impl,
+  attrs= _implicit_deps + _common_attrs + {
+      "prefixes": attr.string_list(default=[]),
+      "suffixes": attr.string_list(default=[]),
+      "print_discovered_classes": attr.bool(default=False, mandatory=False),
+      "_junit": attr.label(default=Label("//external:io_bazel_rules_scala/dependency/junit/junit"), single_file=True),
+      "_hamcrest": attr.label(default=Label("//external:io_bazel_rules_scala/dependency/hamcrest/hamcrest_core"), single_file=True),
+      "_suite": attr.label(default=Label("//src/java/io/bazel/rulesscala/test_discovery:test_discovery")),
+      },
+  outputs={
+      "jar": "%{name}.jar",
+      "deploy_jar": "%{name}_deploy.jar",
+      "manifest": "%{name}_MANIFEST.MF",
+      },
+  test=True,
+)
 
+def scala_specs2_junit_test(name, **kwargs):
+  scala_junit_test(
+   name = name,
+   deps = specs2_junit_dependencies() + kwargs.pop("deps",[]),
+   **kwargs)

scala/scala.bzl

@@ -0,0 +1,50 @@
+def specs2_version():
+  return "3.8.8"
+def specs2_repositories():
+
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_specs2_specs2_core",
+      artifact = "org.specs2:specs2-core_2.11:" + specs2_version(),
+      sha1 = "495bed00c73483f4f5f43945fde63c615d03e637",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/specs2/specs2_core', actual = '@io_bazel_rules_scala_org_specs2_specs2_core//jar')
+  
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_specs2_specs2_common",
+      artifact = "org.specs2:specs2-common_2.11:" + specs2_version(),
+      sha1 = "15bc009eaae3a574796c0f558d8696b57ae903c3",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/specs2/specs2_common', actual = '@io_bazel_rules_scala_org_specs2_specs2_common//jar')
+  
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_specs2_specs2_matcher",
+      artifact = "org.specs2:specs2-matcher_2.11:" + specs2_version(),
+      sha1 = "d2e967737abef7421e47b8994a8c92784e624d62",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/specs2/specs2_matcher', actual = '@io_bazel_rules_scala_org_specs2_specs2_matcher//jar')
+  
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_scalaz_scalaz_effect",
+      artifact = "org.scalaz:scalaz-effect_2.11:7.2.7",
+      sha1 = "824bbb83da12224b3537c354c51eb3da72c435b5",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/scalaz/scalaz_effect', actual = '@io_bazel_rules_scala_org_scalaz_scalaz_effect//jar')
+
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_scalaz_scalaz_core",
+      artifact = "org.scalaz:scalaz-core_2.11:7.2.7",
+      sha1 = "ebf85118d0bf4ce18acebf1d8475ee7deb7f19f1",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/scalaz/scalaz_core', actual = '@io_bazel_rules_scala_org_scalaz_scalaz_core//jar')
+
+def specs2_dependencies():
+  return [
+  "//external:io_bazel_rules_scala/dependency/specs2/specs2_core",
+  "//external:io_bazel_rules_scala/dependency/specs2/specs2_common",
+  "//external:io_bazel_rules_scala/dependency/specs2/specs2_matcher",
+  "//external:io_bazel_rules_scala/dependency/scalaz/scalaz_effect",
+  "//external:io_bazel_rules_scala/dependency/scalaz/scalaz_core",
+  "//external:io_bazel_rules_scala/dependency/scala/scala_xml",
+  "//external:io_bazel_rules_scala/dependency/scala/parser_combinators",
+  "//external:io_bazel_rules_scala/dependency/scala/scala_library",
+  "//external:io_bazel_rules_scala/dependency/scala/scala_reflect"]  

specs2/BUILD

@@ -0,0 +1,16 @@
+load("//specs2:specs2.bzl", "specs2_repositories", "specs2_dependencies", "specs2_version")
+load("//junit:junit.bzl", "junit_repositories")
+  
+def specs2_junit_repositories():
+  specs2_repositories()  
+  junit_repositories()
+  # Aditional dependencies for specs2 junit runner
+  native.maven_jar(
+      name = "io_bazel_rules_scala_org_specs2_specs2_junit_2_11",
+      artifact = "org.specs2:specs2-junit_2.11:" + specs2_version(),
+      sha1 = "1dc9e43970557c308ee313842d84094bc6c1c1b5",
+  )
+  native.bind(name = 'io_bazel_rules_scala/dependency/specs2/specs2_junit', actual = '@io_bazel_rules_scala_org_specs2_specs2_junit_2_11//jar')
+
+def specs2_junit_dependencies():
+    return specs2_dependencies() + ["//external:io_bazel_rules_scala/dependency/specs2/specs2_junit"]

specs2/specs2.bzl

@@ -0,0 +1,8 @@
+load("//scala:scala.bzl", "scala_library")
+
+
+scala_library(name = "test_discovery",
+  srcs = ["DiscoveredTestSuite.scala"],
+  deps = ["//external:io_bazel_rules_scala/dependency/junit/junit"],
+  visibility = ["//visibility:public"],
+  )

specs2/specs2_junit.bzl

@@ -0,0 +1,128 @@
+package io.bazel.rulesscala.test_discovery
+
+import org.junit.runner.RunWith
+import org.junit.runners.Suite
+import org.junit.runners.model.RunnerBuilder
+import java.io.File
+import java.io.FileInputStream
+import java.util.jar.JarInputStream
+import java.util.jar.JarEntry
+/*
+  The test running and discovery mechanism works in the following manner:
+    - Bazel rule executes a JVM application to run tests (currently `JUnitCore`) and asks it to run 
+  the `DiscoveredTestSuite` suite. 
+    - When JUnit tries to run it, it uses the `PrefixSuffixTestDiscoveringSuite` runner
+  to know what tests exist in the suite.
+    - We know which tests to run by examining the entries of the target's archive.
+    - The archive's path is passed in a system property ("bazel.discover.classes.archive.file.path").
+    - The entries of the archive are filtered to keep only classes
+    - Of those we filter again and keep only those which match either of the prefixes/suffixes supplied.
+    - Prefixes are supplied as a comma separated list. System property ("bazel.discover.classes.prefixes")
+    - Suffixes are supplied as a comma separated list. System property ("bazel.discover.classes.prefixes")
+    - We iterate over the remaining entries and format them into classes.
+    - At this point we tell JUnit (via the `RunnerBuilder`) what are the discovered test classes.
+    - W.R.T. discovery semantics this is similar to how maven surefire/failsafe plugins work.
+    - For debugging purposes one can ask to print the list of discovered classes.
+    - This is done via an `print_discovered_classes` attribute.
+    - The attribute is sent via "bazel.discover.classes.print.discovered"
+
+  Additional references:
+    - http://junit.org/junit4/javadoc/4.12/org/junit/runner/RunWith.html
+    - http://junit.org/junit4/javadoc/4.12/org/junit/runners/model/RunnerBuilder.html
+    - http://maven.apache.org/surefire/maven-surefire-plugin/examples/inclusion-exclusion.html
+*/
+@RunWith(classOf[PrefixSuffixTestDiscoveringSuite])
+class DiscoveredTestSuite
+
+class PrefixSuffixTestDiscoveringSuite(testClass: Class[Any], builder: RunnerBuilder)
+  extends Suite(builder, testClass, PrefixSuffixTestDiscoveringSuite.discoverClasses())
+
+object PrefixSuffixTestDiscoveringSuite {
+
+  private def discoverClasses(): Array[Class[_]] = {
+
+    val archive = archiveInputStream()
+    val classes = discoverClasses(archive, prefixes, suffixesWithClassSuffix)
+    archive.close()
+    if (printDiscoveredClasses) {
+      println("Discovered classes:")
+      classes.foreach(c => println(c.getName))
+    }
+    if (classes.isEmpty)
+      throw new IllegalStateException("Was not able to discover any classes " + 
+                                      s"for archive=$archivePath, " +
+                                      s"prefixes=$prefixes, " +
+                                      s"suffixes=$suffixes")
+    classes
+  }
+
+  private def discoverClasses(archive: JarInputStream,
+    prefixes: Set[String],
+    suffixes: Set[String]): Array[Class[_]] =
+    matchingEntries(archive, prefixes, suffixes)
+      .map(dropFileSuffix)
+      .map(fileToClassFormat)
+      .map(Class.forName)
+      .toArray
+
+  private def matchingEntries(archive: JarInputStream,
+    prefixes: Set[String],
+    suffixes: Set[String]) =
+        entries(archive)
+          .filter(isClass)
+          .filter(entry => endsWith(suffixes)(entry) || startsWith(prefixes)(entry))
+
+  private def startsWith(prefixes: Set[String])(entry: String): Boolean = {
+    val entryName = entryFileName(entry)
+    prefixes.exists(entryName.startsWith)
+  }
+
+  private def endsWith(suffixes: Set[String])(entry: String): Boolean = {
+    val entryName = entryFileName(entry)
+    suffixes.exists(entryName.endsWith)
+  }
+
+  private def entryFileName(entry: String): String = 
+    new File(entry).getName
+
+  private def dropFileSuffix(classEntry: String): String =
+    classEntry.split("\\.").head
+
+  private def fileToClassFormat(classEntry: String): String =
+    classEntry.replace('/', '.')
+
+  private def isClass(entry: String): Boolean =
+    entry.endsWith(".class")
+
+  private def entries(jarInputStream: JarInputStream) =
+    Stream.continually(Option(jarInputStream.getNextJarEntry))
+    .takeWhile(_.isDefined)
+    .flatten
+    .map(_.getName)
+    .toList
+
+  private def archiveInputStream() =
+    new JarInputStream(new FileInputStream(archivePath))
+
+  private def archivePath: String =
+    System.getProperty("bazel.discover.classes.archive.file.path")
+
+  private def suffixesWithClassSuffix: Set[String] =
+    suffixes.map(_ + ".class")
+
+  private def suffixes: Set[String] =
+    parseProperty(System.getProperty("bazel.discover.classes.suffixes"))
+
+  private def prefixes: Set[String] =
+    parseProperty(System.getProperty("bazel.discover.classes.prefixes"))
+
+  private def parseProperty(potentiallyEmpty: String): Set[String] =
+    potentiallyEmpty.trim match {
+      case emptyStr if emptyStr.isEmpty => Set[String]()
+      case nonEmptyStr => nonEmptyStr.split(",").toSet
+    }
+
+  private def printDiscoveredClasses: Boolean =
+    System.getProperty("bazel.discover.classes.print.discovered").toBoolean
+
+}