Changing the scoring process for slider questions.

Previously sliders were scored as a value between 1 and 4 based on the
percentage across the screen that the slider was slid. This required you
to slide fully to the right to get a 4.

Now the slider is divided into n sections, where n is the number of answers
on the slider. With 4 answers the score will be exactly 1, 2, 3, or 4.
With more answers you may get a decimals, but the last section of the
slider will always result in a 4.

3 files changed, 85 insertions, 5 deletions

diff --git a/src/com/p4square/grow/model/SliderScoringEngine.java b/src/com/p4square/grow/model/SliderScoringEngine.java
index 76811b3..2961e95 100644
--- a/src/com/p4square/grow/model/SliderScoringEngine.java
+++ b/src/com/p4square/grow/model/SliderScoringEngine.java
@@ -15,12 +15,18 @@ public class SliderScoringEngine extends ScoringEngine {
 
     @Override
     public boolean scoreAnswer(Score score, Question question, RecordedAnswer userAnswer) {
-        float delta = Float.valueOf(userAnswer.getAnswerId()) * 3 + 1;
+        int numberOfAnswers = question.getAnswers().size();
+        if (numberOfAnswers == 0) {
+            throw new IllegalArgumentException("Question has no answers.");
+        }
 
-        if (delta < 0 || delta > 4) {
+        double answer = Double.valueOf(userAnswer.getAnswerId());
+        if (answer < 0 || answer > 1) {
             throw new IllegalArgumentException("Answer out of bounds.");
         }
 
+        double delta = Math.max(1, Math.ceil(answer * numberOfAnswers) / numberOfAnswers * 4);
+
         score.sum += delta;
         score.count++;
 
diff --git a/tst/com/p4square/grow/model/SliderQuestionTest.java b/tst/com/p4square/grow/model/SliderQuestionTest.java
index eaa67b5..b5c4e83 100644
--- a/tst/com/p4square/grow/model/SliderQuestionTest.java
+++ b/tst/com/p4square/grow/model/SliderQuestionTest.java
@@ -26,6 +26,12 @@ public class SliderQuestionTest {
     @Before
     public void setUp() {
         mQuestion = new SliderQuestion();
+
+        // Add some "answers" for the scoring engine.
+        mQuestion.getAnswers().put("1", new Answer());
+        mQuestion.getAnswers().put("2", new Answer());
+        mQuestion.getAnswers().put("3", new Answer());
+        mQuestion.getAnswers().put("4", new Answer());
     }
 
     /**
diff --git a/tst/com/p4square/grow/model/SliderScoringEngineTest.java b/tst/com/p4square/grow/model/SliderScoringEngineTest.java
index fdbfd6f..1ea0d4c 100644
--- a/tst/com/p4square/grow/model/SliderScoringEngineTest.java
+++ b/tst/com/p4square/grow/model/SliderScoringEngineTest.java
@@ -4,6 +4,8 @@
 
 package com.p4square.grow.model;
 
+import java.util.Map;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -32,10 +34,13 @@ public class SliderScoringEngineTest {
     }
 
     /**
-     * Test the scoreAnswer() method.
+     * Test the scoreAnswer() method with four answers.
      */
     @Test
-    public void testScoreAnswer() {
+    public void testScoreAnswerFourAnswers() {
+        // Create the four answers.
+        createAnswers(4);
+
         Score score = new Score();
         RecordedAnswer answer = new RecordedAnswer();
 
@@ -51,11 +56,59 @@ public class SliderScoringEngineTest {
         assertEquals(2, score.count);
         assertEquals(5, score.sum, DELTA);
 
-        // Test fraction (0.33)
+        // Test 0.33. Should be 2.
         answer.setAnswerId("0.33333");
         assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
         assertEquals(3, score.count);
         assertEquals(7, score.sum, DELTA);
+
+        // Test 0.9, should be 4.
+        answer.setAnswerId("0.9");
+        assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
+        assertEquals(4, score.count);
+        assertEquals(11, score.sum, DELTA);
+    }
+
+    /**
+     * Test the scoreAnswer() method with six answers.
+     */
+    @Test
+    public void testScoreAnswerSixAnswers() {
+        // Create the four answers.
+        createAnswers(6);
+
+        Score score = new Score();
+        RecordedAnswer answer = new RecordedAnswer();
+
+        // Test 0
+        answer.setAnswerId("0");
+        assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
+        assertEquals(1, score.count);
+        assertEquals(1, score.sum, DELTA);
+
+        // Test 1
+        answer.setAnswerId("1");
+        assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
+        assertEquals(2, score.count);
+        assertEquals(5, score.sum, DELTA);
+
+        // Test 0.33. Should score as 1.33
+        answer.setAnswerId("0.33333");
+        assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
+        assertEquals(3, score.count);
+        assertEquals(6.3333, score.sum, DELTA);
+
+        // Test 0.55. Should score as 2.66
+        answer.setAnswerId("0.55");
+        assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
+        assertEquals(4, score.count);
+        assertEquals(9, score.sum, DELTA);
+
+        // Test 0.9. Should score as 4.
+        answer.setAnswerId("0.90");
+        assertTrue(mEngine.scoreAnswer(score, mQuestion, answer));
+        assertEquals(5, score.count);
+        assertEquals(13, score.sum, DELTA);
     }
 
     /**
@@ -74,6 +127,7 @@ public class SliderScoringEngineTest {
      */
     @Test(expected = IllegalArgumentException.class)
     public void testNegativeAnswer() {
+        createAnswers(4);
         Score score = new Score();
         RecordedAnswer answer = new RecordedAnswer();
         answer.setAnswerId("-1");
@@ -85,9 +139,23 @@ public class SliderScoringEngineTest {
      */
     @Test(expected = IllegalArgumentException.class)
     public void testAnswerOutOfBounds() {
+        createAnswers(4);
         Score score = new Score();
         RecordedAnswer answer = new RecordedAnswer();
         answer.setAnswerId("1.1");
         mEngine.scoreAnswer(score, mQuestion, answer);
     }
+
+    /**
+     * Helper method to create a number of questions on the slider.
+     * 
+     * @param count Number of answers on the questions.
+     */
+    private void createAnswers(int count) {
+        Map<String, Answer> answers = mQuestion.getAnswers();
+        answers.clear();
+        for (int i = 0; i < count; i++) {
+            answers.put(String.valueOf(i), new Answer());
+        }
+    }
 }