SI-8538 Test or example for Source.report

It's possible to supply an arbitrary `Positioner` to a
custom `Source` that wants to override `report`.

This obviates the need to expose the deprecated `Position` class.

The default report method consumes the underlying iterator, which
is not desirable and produces unexpected results.

The expected outcome is that no one uses or extends the legacy
position handling code.

In 2.12, use a Reporter instead, perhaps. The current API is
used by scala-xml's MarkupParser.

1 files changed, 56 insertions, 0 deletions

diff --git a/test/junit/scala/io/SourceTest.scala b/test/junit/scala/io/SourceTest.scala
new file mode 100644
index 0000000000..efe081f844
--- /dev/null
+++ b/test/junit/scala/io/SourceTest.scala
@@ -0,0 +1,56 @@
+
+package scala.io
+
+import org.junit.Test
+import org.junit.Assert._
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+import scala.tools.testing.AssertUtil._
+
+import java.io.{ Console => _, _ }
+
+@RunWith(classOf[JUnit4])
+class SourceTest {
+
+  private implicit val `our codec` = Codec.UTF8
+  private val charSet = Codec.UTF8.charSet.name
+
+  private def sampler = """
+    |Big-endian and little-endian approaches aren't
+    |readily interchangeable in general, because the
+    |laws of arithmetic send signals leftward from
+    |the bits that are "least significant."
+    |""".stripMargin.trim
+
+  private def in = new ByteArrayInputStream(sampler.getBytes)
+
+  @Test def canIterateLines() = {
+    assertEquals(sampler.lines.size, (Source fromString sampler).getLines.size)
+  }
+  @Test def canCustomizeReporting() = {
+    class CapitalReporting(is: InputStream) extends BufferedSource(is) {
+      override def report(pos: Int, msg: String, out: PrintStream): Unit = {
+        out print f"$pos%04x: ${msg.toUpperCase}"
+      }
+      class OffsetPositioner extends Positioner(null) {
+        override def next(): Char = {
+          ch = iter.next()
+          pos = pos + 1
+          ch
+        }
+      }
+      withPositioning(new OffsetPositioner)
+    }
+    val s = new CapitalReporting(in)
+    // skip to next line and report an error
+    do {
+      val c = s.next()
+    } while (s.ch != '\n')
+    s.next()
+    val out = new ByteArrayOutputStream
+    val ps  = new PrintStream(out, true, charSet)
+    s.reportError(s.pos, "That doesn't sound right.", ps)
+    assertEquals("0030: THAT DOESN'T SOUND RIGHT.", out.toString(charSet))
+  }
+}