Formatting timer to mm:ss

src/com/happyprog/pairhero/views/MainView.java

@@ -64,8 +64,18 @@ public void gameFinished() {
 		dialog.open();
 	}
 
-	public void onTimeChange(int seconds) {
-		updateInfo(timerLabel, String.format("%d", seconds));
+	public void onTimeChange(int timeInSeconds) {
+		int minutes = timeInSeconds / 60;
+		int seconds = timeInSeconds % 60;
+
+		updateInfo(timerLabel, String.format("%s:%s", withZeroes(minutes), withZeroes(seconds)));
+	}
+
+	private String withZeroes(int time) {
+		if (time < 10) {
+			return String.format("0%d", time);
+		}
+		return String.format("%d", time);
 	}
 
 	private void updateInfo(final Label label, final String text) {

test/com/happyprog/pairhero/views/TimeFormatLearningTest.java

@@ -0,0 +1,51 @@
+package com.happyprog.pairhero.views;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class TimeFormatLearningTest {
+	@Test
+	public void oneSecond() throws Exception {
+		assertEquals("00:01", format(1));
+	}
+
+	@Test
+	public void twentySeconds() throws Exception {
+		assertEquals("00:20", format(20));
+	}
+
+	@Test
+	public void oneMinute() throws Exception {
+		assertEquals("01:00", format(60));
+	}
+
+	@Test
+	public void oneMinuteAndThirtySeconds() throws Exception {
+		assertEquals("01:30", format(90));
+	}
+
+	@Test
+	public void twentyFiveMinutes() throws Exception {
+		assertEquals("25:00", format(1500));
+	}
+
+	@Test
+	public void twentyFourMinutesAndFiftyNineSeconds() throws Exception {
+		assertEquals("24:59", format(1499));
+	}
+
+	private String format(int time) {
+		int minutes = time / 60;
+		int seconds = time % 60;
+
+		return String.format("%s:%s", fill(minutes), fill(seconds));
+	}
+
+	private Object fill(int seconds) {
+		if (seconds < 10) {
+			return String.format("0%d", seconds);
+		}
+		return String.format("%d", seconds);
+	}
+}