test: add ScoreOfFilterMatchTest

Author: sebthom

org.eclipse.lsp4e.test/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: Tests for language server bundle (Incubation)
 Bundle-SymbolicName: org.eclipse.lsp4e.test;singleton:=true
-Bundle-Version: 0.15.22.qualifier
+Bundle-Version: 0.15.23.qualifier
 Fragment-Host: org.eclipse.lsp4e
 Bundle-Vendor: Eclipse LSP4E
 Bundle-RequiredExecutionEnvironment: JavaSE-17

org.eclipse.lsp4e.test/pom.xml

@@ -8,7 +8,7 @@
 	</parent>
 	<artifactId>org.eclipse.lsp4e.test</artifactId>
 	<packaging>eclipse-test-plugin</packaging>
-	<version>0.15.22-SNAPSHOT</version>
+	<version>0.15.23-SNAPSHOT</version>
 
 	<properties>
 		<os-jvm-flags /> <!-- for the default case -->

org.eclipse.lsp4e.test/src/org/eclipse/lsp4e/test/completion/ScoreOfFilterMatchTest.java

@@ -0,0 +1,137 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Vegard IT GmbH and others.
+ * This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License 2.0
+ * which is available at https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *  Sebastian Thomschke (Vegard IT GmbH) - initial implementation
+ *******************************************************************************/
+package org.eclipse.lsp4e.test.completion;
+
+import static org.junit.Assert.*;
+
+import java.util.Random;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import org.eclipse.lsp4e.operations.completion.CompletionProposalTools;
+import org.junit.Test;
+
+/**
+ * Test cases for {@link CompletionProposalTools#getScoreOfFilterMatch(String, String)}
+ */
+public class ScoreOfFilterMatchTest {
+	private static final Random RANDOM = new Random();
+
+	private static String generateRandomString(final int maxLength) {
+		final var length = RANDOM.nextInt(maxLength + 1);
+		if (length == 0)
+			return "";
+		var chars = "abcdefghijklmnopqrstuvwxyzäöüß";
+		chars = "_" + chars + chars.toUpperCase();
+		final var sb = new StringBuilder(length);
+		for (int i = 0; i < length; i++) {
+			sb.append(chars.charAt(RANDOM.nextInt(chars.length())));
+		}
+		return sb.toString();
+	}
+
+	@Test
+	public void testCaseInsensitivity() {
+		final var documentFilter = "Example";
+		final var completionFilter = "eXaMpLe";
+		final int expectedScore = 0;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should be 0 for case-insensitive matches.", expectedScore, actualScore);
+	}
+
+	@Test
+	public void testEmptyCompletionFilter() {
+		final var documentFilter = "example";
+		final var completionFilter = "";
+		final int expectedScore = -1;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should be -1 for an empty completionFilter.", expectedScore, actualScore);
+	}
+
+	@Test
+	public void testEmptyDocumentFilter() {
+		final var documentFilter = "";
+		final var completionFilter = "example";
+		final int expectedScore = 0;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should be 0 for an empty documentFilter.", expectedScore, actualScore);
+	}
+
+	/**
+	 * Test case for https://github.com/eclipse-lsp4e/lsp4e/issues/1132
+	 */
+	@Test
+	public void testRandomFilters() {
+		final int testCases = 50_000; // Number of random test cases to try
+		final int timeoutMS = 3; // Timeout threshold for detecting infinite loops
+
+		final var executor = Executors.newSingleThreadExecutor();
+
+		for (int i = 0; i < testCases; i++) {
+			final var commonPrefix = generateRandomString(2); // String with length of 0-2 chars
+			final var documentFilter = commonPrefix + generateRandomString(5);
+			final var completionFilter = commonPrefix + generateRandomString(15);
+
+			final var future = executor
+					.submit(() -> CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter));
+
+			try {
+				future.get(timeoutMS, TimeUnit.SECONDS);
+			} catch (final TimeoutException e) {
+				future.cancel(true); // Interrupt stuck execution
+				fail("Possible infinite loop detected in getScoreOfFilterMatch with inputs: " + "documentFilter='"
+						+ documentFilter + "', completionFilter='" + completionFilter + "'");
+			} catch (Exception e) {
+				fail("Unexpected exception: " + e.getMessage());
+			}
+		}
+
+		executor.shutdown();
+	}
+
+	@Test
+	public void testExactMatch() {
+		final var documentFilter = "example";
+		final var completionFilter = "example";
+		final int expectedScore = 0;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should be 0 for exact matches.", expectedScore, actualScore);
+	}
+
+	@Test
+	public void testNoMatch() {
+		final var documentFilter = "foo";
+		final var completionFilter = "example";
+		final int expectedScore = -1;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should be -1 when there's no match.", expectedScore, actualScore);
+	}
+
+	@Test
+	public void testPrefixMatch() {
+		final var documentFilter = "ex";
+		final var completionFilter = "example";
+		final int expectedScore = 0;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should be 0 when documentFilter is a prefix.", expectedScore, actualScore);
+	}
+
+	@Test
+	public void testScatteredMatch() {
+		final var documentFilter = "eap";
+		final var completionFilter = "example";
+		final int expectedScore = 6;
+		final int actualScore = CompletionProposalTools.getScoreOfFilterMatch(documentFilter, completionFilter);
+		assertEquals("The score should account for scattered characters.", expectedScore, actualScore);
+	}
+}