Refactor unit tests for vector functions. (#48662)

This PR performs the following changes:
* Split `ScoreScriptUtilsTests` into `DenseVectorFunctionTests` and
`SparseVectorFunctionTests`. This will make it easier to delete all sparse
vector function tests once we remove support on 8.x.
* As much as possible, break up the large test methods into individual tests
for each vector function (`cosineSimilarity`, `l2norm`, etc.).

x-pack/plugin/vectors/src/test/java/org/elasticsearch/xpack/vectors/query/DenseVectorFunctionTests.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+package org.elasticsearch.xpack.vectors.query;
+
+import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.Version;
+import org.elasticsearch.script.ScoreScript;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xpack.vectors.query.ScoreScriptUtils.CosineSimilarity;
+import org.elasticsearch.xpack.vectors.query.ScoreScriptUtils.DotProduct;
+import org.elasticsearch.xpack.vectors.query.ScoreScriptUtils.L1Norm;
+import org.elasticsearch.xpack.vectors.query.ScoreScriptUtils.L2Norm;
+import org.elasticsearch.xpack.vectors.query.VectorScriptDocValues.DenseVectorScriptDocValues;
+import org.junit.Before;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.elasticsearch.xpack.vectors.mapper.VectorEncoderDecoderTests.mockEncodeDenseVector;
+import static org.hamcrest.Matchers.containsString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class DenseVectorFunctionTests extends ESTestCase {
+    private String field;
+    private float[] docVector;
+    private List<Number> queryVector;
+    private List<Number> invalidQueryVector;
+
+    @Before
+    public void setUpVectors() {
+        field = "vector";
+        docVector = new float[] {230.0f, 300.33f, -34.8988f, 15.555f, -200.0f};
+        queryVector = Arrays.asList(0.5f, 111.3f, -13.0f, 14.8f, -156.0f);
+        invalidQueryVector = Arrays.asList(0.5, 111.3);
+    }
+
+    public void testDenseVectorFunctions() {
+        for (Version indexVersion : Arrays.asList(Version.V_7_4_0, Version.CURRENT)) {
+            BytesRef encodedDocVector = mockEncodeDenseVector(docVector, indexVersion);
+            DenseVectorScriptDocValues docValues = mock(DenseVectorScriptDocValues.class);
+            when(docValues.getEncodedValue()).thenReturn(encodedDocVector);
+
+            ScoreScript scoreScript = mock(ScoreScript.class);
+            when(scoreScript._getIndexVersion()).thenReturn(indexVersion);
+            when(scoreScript.getDoc()).thenReturn(Collections.singletonMap(field, docValues));
+
+            testDotProduct(docValues, scoreScript);
+            testCosineSimilarity(docValues, scoreScript);
+            testL1Norm(docValues, scoreScript);
+            testL2Norm(docValues, scoreScript);
+        }
+    }
+
+    private void testDotProduct(DenseVectorScriptDocValues docValues, ScoreScript scoreScript) {
+        DotProduct function = new DotProduct(scoreScript, queryVector, field);
+        double result = function.dotProduct();
+        assertEquals("dotProduct result is not equal to the expected value!", 65425.624, result, 0.001);
+
+        DotProduct deprecatedFunction = new DotProduct(scoreScript, queryVector, docValues);
+        double deprecatedResult = deprecatedFunction.dotProduct();
+        assertEquals("dotProduct result is not equal to the expected value!", 65425.624, deprecatedResult, 0.001);
+        assertWarnings(ScoreScriptUtils.DEPRECATION_MESSAGE);
+
+        DotProduct invalidFunction = new DotProduct(scoreScript, invalidQueryVector, field);
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, invalidFunction::dotProduct);
+        assertThat(e.getMessage(), containsString("query vector has a different number of dimensions [2] than the document vectors [5]"));
+    }
+
+    private void testCosineSimilarity(DenseVectorScriptDocValues docValues, ScoreScript scoreScript) {
+        CosineSimilarity function = new CosineSimilarity(scoreScript, queryVector, field);
+        double result = function.cosineSimilarity();
+        assertEquals("cosineSimilarity result is not equal to the expected value!", 0.790, result, 0.001);
+
+        CosineSimilarity deprecatedFunction = new CosineSimilarity(scoreScript, queryVector, docValues);
+        double deprecatedResult = deprecatedFunction.cosineSimilarity();
+        assertEquals("cosineSimilarity result is not equal to the expected value!", 0.790, deprecatedResult, 0.001);
+        assertWarnings(ScoreScriptUtils.DEPRECATION_MESSAGE);
+
+        CosineSimilarity invalidFunction = new CosineSimilarity(scoreScript, invalidQueryVector, field);
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, invalidFunction::cosineSimilarity);
+        assertThat(e.getMessage(), containsString("query vector has a different number of dimensions [2] than the document vectors [5]"));
+    }
+
+    private void testL1Norm(DenseVectorScriptDocValues docValues, ScoreScript scoreScript) {
+        L1Norm function = new L1Norm(scoreScript, queryVector, field);
+        double result = function.l1norm();
+        assertEquals("l1norm result is not equal to the expected value!", 485.184, result, 0.001);
+
+        L1Norm deprecatedFunction = new L1Norm(scoreScript, queryVector, docValues);
+        double deprecatedResult = deprecatedFunction.l1norm();
+        assertEquals("l1norm result is not equal to the expected value!", 485.184, deprecatedResult, 0.001);
+        assertWarnings(ScoreScriptUtils.DEPRECATION_MESSAGE);
+
+        L1Norm invalidFunction = new L1Norm(scoreScript, invalidQueryVector, field);
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, invalidFunction::l1norm);
+        assertThat(e.getMessage(), containsString("query vector has a different number of dimensions [2] than the document vectors [5]"));
+    }
+
+    private void testL2Norm(DenseVectorScriptDocValues docValues, ScoreScript scoreScript) {
+        L2Norm function = new L2Norm(scoreScript, queryVector, field);
+        double result = function.l2norm();
+        assertEquals("l2norm result is not equal to the expected value!", 301.361, result, 0.001);
+
+        L2Norm deprecatedFunction = new L2Norm(scoreScript, queryVector, docValues);
+        double deprecatedResult = deprecatedFunction.l2norm();
+        assertEquals("l2norm result is not equal to the expected value!", 301.361, deprecatedResult, 0.001);
+        assertWarnings(ScoreScriptUtils.DEPRECATION_MESSAGE);
+
+        L2Norm invalidFunction = new L2Norm(scoreScript, invalidQueryVector, field);
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, invalidFunction::l2norm);
+        assertThat(e.getMessage(), containsString("query vector has a different number of dimensions [2] than the document vectors [5]"));
+    }
+}