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diff --git a/watchmaker/framework/src/java/test/org/uncommons/watchmaker/framework/selection/TruncationSelectionTest.java b/watchmaker/framework/src/java/test/org/uncommons/watchmaker/framework/selection/TruncationSelectionTest.java
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+//=============================================================================
+// Copyright 2006-2010 Daniel W. Dyer
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//=============================================================================
+package org.uncommons.watchmaker.framework.selection;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.testng.annotations.Test;
+import org.uncommons.watchmaker.framework.EvaluatedCandidate;
+import org.uncommons.watchmaker.framework.SelectionStrategy;
+
+/**
+ * Unit test for truncation selection strategy.  Ensures the
+ * correct candidates are selected.
+ * @author Daniel Dyer
+ */
+public class TruncationSelectionTest
+{
+    @Test
+    public void testNaturalFitnessSelection()
+    {
+        SelectionStrategy<Object> selector = new TruncationSelection(0.5d);
+        List<EvaluatedCandidate<String>> population = new ArrayList<EvaluatedCandidate<String>>(4);
+        // Higher score is better.
+        EvaluatedCandidate<String> steve = new EvaluatedCandidate<String>("Steve", 10.0);
+        EvaluatedCandidate<String> mary = new EvaluatedCandidate<String>("Mary", 9.1);
+        EvaluatedCandidate<String> john = new EvaluatedCandidate<String>("John", 8.4);
+        EvaluatedCandidate<String> gary = new EvaluatedCandidate<String>("Gary", 6.2);
+        population.add(steve);
+        population.add(mary);
+        population.add(john);
+        population.add(gary);
+        List<String> selection = selector.select(population, true, 2, null);
+        assert selection.size() == 2 : "Selection size is " + selection.size() + ", should be 2.";
+        assert selection.contains(steve.getCandidate()) : "Best candidate not selected.";
+        assert selection.contains(mary.getCandidate()) : "Second best candidate not selected.";
+    }
+
+
+    @Test
+    public void testNonNaturalFitnessSelection()
+    {
+        SelectionStrategy<Object> selector = new TruncationSelection(0.5d);
+        List<EvaluatedCandidate<String>> population = new ArrayList<EvaluatedCandidate<String>>(4);
+        // Lower score is better.
+        EvaluatedCandidate<String> gary = new EvaluatedCandidate<String>("Gary", 6.2);
+        EvaluatedCandidate<String> john = new EvaluatedCandidate<String>("John", 8.4);
+        EvaluatedCandidate<String> mary = new EvaluatedCandidate<String>("Mary", 9.1);
+        EvaluatedCandidate<String> steve = new EvaluatedCandidate<String>("Steve", 10.0);
+        population.add(gary);
+        population.add(john);
+        population.add(mary);
+        population.add(steve);
+        List<String> selection = selector.select(population, false, 2, null);
+        assert selection.size() == 2 : "Selection size is " + selection.size() + ", should be 2.";
+        assert selection.contains(gary.getCandidate()) : "Best candidate not selected.";
+        assert selection.contains(john.getCandidate()) : "Second best candidate not selected.";
+    }
+
+
+    /**
+     * The selection ratio must be greater than zero to be useful.  This test
+     * ensures that an appropriate exception is thrown if the ratio is not positive.
+     * Not throwing an exception is an error because it permits undetected bugs in
+     * evolutionary programs.
+     */
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    public void testZeroRatio()
+    {
+        new TruncationSelection(0d);
+    }
+
+
+    /**
+     * The selection ratio must be less than 1 to be useful.  This test
+     * ensures that an appropriate exception is thrown if the ratio is too high.
+     * Not throwing an exception is an error because it permits undetected bugs in
+     * evolutionary programs.
+     */
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    public void testRatioTooHigh()
+    {
+        new TruncationSelection(1d);
+    }
+}