SI-8027 REPL double tab regression

Where did double tab go?  "The shadow knows."

The regression was introduced by the last flurry
before we were left to wallow in whatever white
space remained.

Some xs put other xs under erasure.

It's clear that somebody's daughter walked into
the room and asked for a story, because, shockingly,
the case arrows don't line up.

We need a plug-in for Jenkins, or I guess Travis, to
fail the build if arrows and equals don't align,
because it clearly indicates a lapse of some kind.

1 files changed, 52 insertions, 0 deletions

diff --git a/test/junit/scala/reflect/internal/util/StringOpsTest.scala b/test/junit/scala/reflect/internal/util/StringOpsTest.scala
new file mode 100644
index 0000000000..13d3a6435e
--- /dev/null
+++ b/test/junit/scala/reflect/internal/util/StringOpsTest.scala
@@ -0,0 +1,52 @@
+package scala.reflect.internal.util
+
+import org.junit.Assert._
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+@RunWith(classOf[JUnit4])
+class StringOpsTest {
+  @Test
+  def prefixOfNone(): Unit = {
+    val so = new StringOps { }
+    val ss = Nil
+    val lcp = so longestCommonPrefix ss
+    assert(lcp == "")
+  }
+  @Test
+  def prefixWithEmpty(): Unit = {
+    val so = new StringOps { }
+    val ss = List("abc", "", "abd")
+    val lcp = so longestCommonPrefix ss
+    assert(lcp == "")
+  }
+  @Test
+  def prefixOfOne(): Unit = {
+    val so = new StringOps { }
+    val ss = List("abc")
+    val lcp = so longestCommonPrefix ss
+    assert(lcp == "abc")
+  }
+  @Test
+  def prefixOfMany(): Unit = {
+    val so = new StringOps { }
+    val ss = List("abc", "abd", "abe")
+    val lcp = so longestCommonPrefix ss
+    assert(lcp == "ab")
+  }
+  @Test
+  def prefixOfPrefix(): Unit = {
+    val so = new StringOps { }
+    val ss = List("abc", "abcd")
+    val lcp = so longestCommonPrefix ss
+    assert(lcp == "abc")
+  }
+  @Test
+  def prefixOfPrefixMiddling(): Unit = {
+    val so = new StringOps { }
+    val ss = List("abce", "abc", "abcd")
+    val lcp = so longestCommonPrefix ss
+    assert(lcp == "abc")
+  }
+}