Support breaks between multiple texts.

Sometimes it is necessary to simulate breaks in the user input from
System.in. This can now be achieved by providing multiple texts.

    systemInMock.provide("foo\n", "bar\n");

The change has its seeds in a Stackoverflow question:
http://stackoverflow.com/questions/28505418/what-is-causing-to-junit-and-system-rules-to-fail-on-this-students-submission

README.md

@@ -14,7 +14,7 @@ System Rules is available from
     <dependency>
       <groupId>com.github.stefanbirkner</groupId>
       <artifactId>system-rules</artifactId>
-      <version>1.8.0</version>
+      <version>1.9.0</version>
     </dependency>
 
 Please don't forget to add the scope `test` if you're using System

src/main/java/org/junit/contrib/java/lang/system/TextFromStandardInputStream.java

@@ -2,10 +2,13 @@
 
 import static java.lang.System.in;
 import static java.lang.System.setIn;
+import static java.util.Arrays.asList;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringReader;
+import java.util.Iterator;
+import java.util.List;
 
 import org.junit.rules.ExternalResource;
 
@@ -28,6 +31,20 @@
  *     }
  *   }
  * </pre>
+ *
+ * <h3>Multiple Texts</h3>
+ * You can simulate a user that stops typing and continues afterwards
+ * by providing multiple texts.
+ * <pre>
+ *   &#064;Test
+ *   public void readTextFromStandardInputStream() {
+ *     systemInMock.provide("foo\n", "bar\n");
+ *     Scanner firstScanner = new Scanner(System.in);
+ *     scanner.nextLine();
+ *     Scanner secondScanner = new Scanner(System.in);
+ *     assertEquals("bar", scanner.nextLine());
+ *   }
+ * </pre>
  */
 public class TextFromStandardInputStream extends ExternalResource {
 	private final SystemInMock systemInMock = new SystemInMock();
@@ -42,15 +59,22 @@ public static TextFromStandardInputStream emptyStandardInputStream() {
 	 * specified text.
 	 *
 	 * @param text this text is return by {@code System.in}.
-	 * @deprecated use {@link #provideText(String)}
+	 * @deprecated use {@link #provideText(String...)}
 	 */
 	@Deprecated
 	public TextFromStandardInputStream(String text) {
 		provideText(text);
 	}
 
-	public void provideText(String text) {
-		systemInMock.provideText(text);
+	/**
+	 * Set the text that is returned by {@code System.in}. You can
+	 * provide multiple texts. In that case {@code System.in.read()}
+	 * returns -1 once when the end of a single text is reached and
+	 * continues with the next text afterwards.
+	 * @param texts a list of texts.
+	 */
+	public void provideText(String... texts) {
+		systemInMock.provideText(asList(texts));
 	}
 
 	@Override
@@ -65,15 +89,34 @@ protected void after() {
 	}
 
 	private static class SystemInMock extends InputStream {
-		private StringReader reader;
+		private Iterator<String> texts;
+		private StringReader currentReader;
 
-		public void provideText(String text) {
-			reader = new StringReader(text);
+		public void provideText(List<String> texts) {
+			this.texts = texts.iterator();
+			optionallyCreateReaderForNextText();
 		}
 
 		@Override
 		public int read() throws IOException {
-			return reader.read();
+			if (currentReader == null)
+				return -1;
+			else
+				return readFromExistingReader();
+		}
+
+		private int readFromExistingReader() throws IOException {
+			int character = currentReader.read();
+			if (character == -1)
+				optionallyCreateReaderForNextText();
+			return character;
+		}
+
+		private void optionallyCreateReaderForNextText() {
+			if (texts.hasNext())
+				currentReader = new StringReader(texts.next());
+			else
+				currentReader = null;
 		}
 	}
 }

src/test/java/org/junit/contrib/java/lang/system/TextFromStandardInputStreamTest.java

@@ -29,6 +29,33 @@ public void provideText() throws Throwable {
 		assertThat(statement.textFromSystemIn, is(equalTo(ARBITRARY_TEXT)));
 	}
 
+	@Test
+	public void providesMultipleTexts() throws Throwable {
+		executeRuleWithStatement(new Statement() {
+			@Override
+			public void evaluate() throws Throwable {
+				systemInMock.provideText("first text\n", "second text\n");
+				Scanner firstScanner = new Scanner(System.in);
+				firstScanner.nextLine();
+				Scanner secondScanner = new Scanner(System.in);
+				String textFromSystemIn = secondScanner.nextLine();
+				assertThat(textFromSystemIn, is(equalTo("second text")));
+			}
+		});
+	}
+
+	@Test
+	public void doesNotFailForNoProvidedText() throws Throwable {
+		executeRuleWithStatement(new Statement() {
+			@Override
+			public void evaluate() throws Throwable {
+				systemInMock.provideText();
+				int character = System.in.read();
+				assertThat(character, is(-1));
+			}
+		});
+	}
+
 	@Test
 	public void restoreSystemIn() throws Throwable {
 		InputStream originalSystemIn = System.in;