Always use jdk8 for sbt (fix scala#77)

Author: MasseGuillaume

.travis.yml

@@ -5,10 +5,14 @@ scala:
   - 2.12.6
   - 2.13.0-M4
 jdk:
-  - openjdk7
+  - openjdk6
   - oraclejdk8
 env:
   global:
+    # force jdk 8 for sbt due to sonatype droping support for jdk6 on https (TLS 1.0)
+    # https://stackoverflow.com/questions/50824789/why-am-i-getting-received-fatal-alert-protocol-version-or-peer-not-authentic/50824799#50824799
+    - JAVA_HOME: /usr/lib/jvm/java-8-oracle
+
     # PGP_PASSPHRASE
     - secure: "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"
     # SONA_USER
@@ -23,10 +27,10 @@ env:
 matrix:
   exclude:
     # > 2.12 requires jdk8
-    - jdk: openjdk7
+    - jdk: openjdk6
       scala: 2.12.6
 
-    - jdk: openjdk7
+    - jdk: openjdk6
       scala: 2.13.0-M4
 
     # ?
@@ -45,9 +49,9 @@ matrix:
 
 # | jdk         |   scala   | scala target | scala target version | scalafix test |
 # | ----------- | --------- | ------------ | -------------------- |---------------|
-# |    openjdk7 | 2.11.12   | jvm          |                      |               |
-# |    openjdk7 | 2.11.12   | js           | 0.6.23               |               |
-# |    openjdk7 | 2.11.12   | js           | 1.0.0-M3             |               |
+# |    openjdk6 | 2.11.12   | jvm          |                      |               |
+# |    openjdk6 | 2.11.12   | js           | 0.6.23               |               |
+# |    openjdk6 | 2.11.12   | js           | 1.0.0-M3             |               |
 # |  oraclejdk8 | 2.12.6    | jvm          |                      |               |
 # |  oraclejdk8 | 2.12.6    | js           | 0.6.23               |               |
 # |  oraclejdk8 | 2.12.6    | js           | 1.0.0-M3             |               |

build.sbt

@@ -33,6 +33,23 @@ lazy val compat = crossProject(JSPlatform, JVMPlatform)
   .jvmSettings(
     OsgiKeys.exportPackage := Seq(s"scala.collection.compat.*;version=${version.value}"),
     libraryDependencies += "com.novocode" % "junit-interface" % "0.11" % "test"
+    javaHome := {
+      val oldValue = javaHome.value
+      val isOnCi = sys.env.get("CI").isDefined
+
+      if (isOnCi) {
+        // switch back to the jdk set by the build matrix
+        val ciJavaHome =
+          sys.env("TRAVIS_JDK_VERSION") match {
+            case "openjdk6"   => "/usr/lib/jvm/java-6-openjdk-amd64"
+            case "oraclejdk8" => "/usr/lib/jvm/java-8-oracle"
+          }
+
+        println(s"using JAVA_HOME: $ciJavaHome")
+        Some(file(ciJavaHome))
+      }
+      else oldValue
+    }
   )
   .jsSettings(
     scalacOptions += {

compat/src/test/scala/test/scala/collection/JdkVersionTest.scala

@@ -0,0 +1,25 @@
+package test.scala.collection
+
+import org.junit.Assert._
+import org.junit.Test
+
+class JdkVersionTest {
+
+  @Test
+  def testJavaVersion: Unit = {
+    val isOnCi = sys.env.get("CI").isDefined
+
+    if (isOnCi) {
+      val travisJdkVersion = sys.env("TRAVIS_JDK_VERSION")
+      val jdkVersion = sys.props("java.specification.version")
+
+      if (travisJdkVersion == "openjdk6") {
+        assertEquals(jdkVersion, "1.8")
+      } else if (travisJdkVersion == "oraclejdk8") {
+        assertEquals(jdkVersion, "1.6")
+      } else {
+        throw new Exception(s"Unknown CI jdk version: $travisJdkVersion")
+      }
+    }
+  }
+}