Unit tests added

Author: mridula-s109

x-pack/plugin/rank-rrf/src/test/java/org/elasticsearch/xpack/rank/linear/L2ScoreNormalizerTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+ package org.elasticsearch.xpack.rank.linear;
+
+import org.apache.lucene.search.ScoreDoc;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class L2ScoreNormalizerTests {
+
+    @Test
+    public void testNormalizeTypicalVector() {
+        ScoreDoc[] docs = {
+            new ScoreDoc(1, 3.0f, 0),
+            new ScoreDoc(2, 4.0f, 0)
+        };
+        ScoreDoc[] normalized = L2ScoreNormalizer.INSTANCE.normalizeScores(docs);
+        Assert.assertEquals(0.6f, normalized[0].score, 1e-5);
+        Assert.assertEquals(0.8f, normalized[1].score, 1e-5);
+    }
+
+    @Test
+    public void testAllZeros() {
+        ScoreDoc[] docs = {
+            new ScoreDoc(1, 0.0f, 0),
+            new ScoreDoc(2, 0.0f, 0)
+        };
+        ScoreDoc[] normalized = L2ScoreNormalizer.INSTANCE.normalizeScores(docs);
+        Assert.assertEquals(0.0f, normalized[0].score, 0.0f);
+        Assert.assertEquals(0.0f, normalized[1].score, 0.0f);
+    }
+
+    @Test
+    public void testAllNaN() {
+        ScoreDoc[] docs = {
+            new ScoreDoc(1, Float.NaN, 0),
+            new ScoreDoc(2, Float.NaN, 0)
+        };
+        ScoreDoc[] normalized = L2ScoreNormalizer.INSTANCE.normalizeScores(docs);
+        Assert.assertTrue(Float.isNaN(normalized[0].score));
+        Assert.assertTrue(Float.isNaN(normalized[1].score));
+    }
+
+    @Test
+    public void testMixedZeroAndNaN() {
+        ScoreDoc[] docs = {
+            new ScoreDoc(1, 0.0f, 0),
+            new ScoreDoc(2, Float.NaN, 0)
+        };
+        ScoreDoc[] normalized = L2ScoreNormalizer.INSTANCE.normalizeScores(docs);
+        Assert.assertEquals(0.0f, normalized[0].score, 0.0f);
+        Assert.assertTrue(Float.isNaN(normalized[1].score));
+    }
+
+    @Test
+    public void testSingleElement() {
+        ScoreDoc[] docs = {
+            new ScoreDoc(1, 42.0f, 0)
+        };
+        ScoreDoc[] normalized = L2ScoreNormalizer.INSTANCE.normalizeScores(docs);
+        Assert.assertEquals(1.0f, normalized[0].score, 1e-5);
+    }
+
+    @Test
+    public void testEmptyArray() {
+        ScoreDoc[] docs = {};
+        ScoreDoc[] normalized = L2ScoreNormalizer.INSTANCE.normalizeScores(docs);
+        Assert.assertEquals(0, normalized.length);
+    }
+}