Refactor testing logic for only running under certain JDK versions

We had several tests designed to only run if the JDK version was at
least some specified version. This commit refactors that common logic
into DirectTest.

Author: James Iry

src/partest/scala/tools/partest/DirectTest.scala

@@ -6,6 +6,7 @@
 package scala.tools.partest
 
 import scala.tools.nsc._
+import settings.ScalaVersion
 import io.Directory
 import util.{ SourceFile, BatchSourceFile, CommandLineParser }
 import reporters.{Reporter, ConsoleReporter}
@@ -101,4 +102,30 @@ abstract class DirectTest extends App {
   final def log(msg: => Any) {
     if (isDebug) Console.err println msg
   }
+
+  /**
+   * Run a test only if the current java version is at least the version specified.
+   */
+  def testUnderJavaAtLeast[A](version: String)(yesRun: =>A) = new TestUnderJavaAtLeast(version, { yesRun })
+
+  class TestUnderJavaAtLeast[A](version: String, yesRun: => A) {
+    val javaVersion = System.getProperty("java.specification.version")
+
+    // the "ScalaVersion" class parses Java specification versions just fine
+    val requiredJavaVersion = ScalaVersion(version)
+    val executingJavaVersion = ScalaVersion(javaVersion)
+    val shouldRun = executingJavaVersion >= requiredJavaVersion
+    val preamble = if (shouldRun) "Attempting" else "Doing fallback for"
+
+    def logInfo() = log(s"$preamble java $version specific test under java version $javaVersion")
+ 
+   /*
+    * If the current java version is at least 'version' then 'yesRun' is evaluated
+    * otherwise 'fallback' is 
+    */
+    def otherwise(fallback: =>A): A = {
+      logInfo()
+      if (shouldRun) yesRun else fallback
+    }
+  }
 }

test/files/run/classfile-format-51.scala

@@ -112,12 +112,12 @@ object Driver {
     System.setErr(System.out)
     try {
       // this test is only valid under JDK 1.7+
-      // cheat a little by using 'ScalaVersion' because it can parse java versions just as well
-      val requiredJavaVersion = ScalaVersion("1.7")
-      val executingJavaVersion = ScalaVersion(System.getProperty("java.specification.version"))
-      if (executingJavaVersion >= requiredJavaVersion) {
+      testUnderJavaAtLeast("1.7") {  
         generateClass()
         compile()
+        ()
+      } otherwise {
+        ()
       }
     } 
     finally

test/files/run/classfile-format-52.scala

@@ -61,17 +61,14 @@ class Driver extends HasDefaultMethod {
     System.setErr(System.out)
     try {
       // this test is only valid under JDK 1.8+
-      // cheat a little by using 'ScalaVersion' because it can parse java versions just as well
-      val requiredJavaVersion = ScalaVersion("1.8")
-      val executingJavaVersion = ScalaVersion(System.getProperty("java.specification.version"))
-      if (executingJavaVersion >= requiredJavaVersion) {
+      testUnderJavaAtLeast("1.8") {
         generateInterface()
         compile()
         Class.forName("Driver").newInstance()
-      } else {
-        // under other versions just dump the expected results
+        ()   
+      } otherwise {
         println("hello from publicMethod")
-        println("hello from staticMethod")
+        println("hello from staticMethod")        
       }
     } 
     finally

test/files/run/t7398.scala

@@ -3,14 +3,11 @@ import scala.tools.partest._
 object Test extends CompilerTest {
   import global._
 
-  def javaVersion = scala.util.Properties.javaVersion
-  def isJavaEight = javaVersion startsWith "1.8"
   // This way we auto-pass on non-java8 since there's nothing to check
-  override lazy val units = {
-    val res: List[CompilationUnit]  = if (isJavaEight) javaCompilationUnits(global)(defaultMethodSource) else Nil
-    val word = if (isJavaEight) "Attempting" else "Skipping"
-    log(s"$word java8-specific test under java version $javaVersion")
-    res
+  override lazy val units: List[CompilationUnit]  = testUnderJavaAtLeast("1.8") {
+    javaCompilationUnits(global)(defaultMethodSource)
+  } otherwise {
+    Nil
   }
 
   private def defaultMethodSource = """