Add a thorough UrlManipulator test suite

cast/js/src/test/java/com/ibm/wala/cast/js/html/UrlManipulatorTest.java

@@ -0,0 +1,124 @@
+package com.ibm.wala.cast.js.html;
+
+import static com.ibm.wala.cast.js.html.UrlManipulator.relativeToAbsoluteUrl;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.fail;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+import org.junit.jupiter.api.Test;
+
+/** Tests for {@link UrlManipulator#relativeToAbsoluteUrl(String, URL)} */
+public class UrlManipulatorTest {
+
+  private static void check(String context, String found, String expected) {
+    try {
+      // We use `hasToString` here instead of `isEqualTo` because `URL.equals` entails DNS
+      // resolution.
+      assertThat(relativeToAbsoluteUrl(found, new URL(context))).hasToString(expected);
+    } catch (MalformedURLException problem) {
+      fail(problem);
+    }
+  }
+
+  private static void checkNull(URL context, String found) {
+    assertThatCode(() -> relativeToAbsoluteUrl(found, context))
+        .isInstanceOf(NullPointerException.class);
+  }
+
+  @Test
+  public void testAbsoluteUrl() {
+    check(
+        "https://example.org/path/",
+        "https://example.com/resource",
+        "https://example.com/resource");
+  }
+
+  @Test
+  public void testProtocolRelativeUrl() {
+    check("https://example.org/path/", "//example.com/resource", "https://example.com/resource");
+  }
+
+  @Test
+  public void testProtocolRelativeUrlWithoutPath() {
+    check("https://example.org/path/", "//example.com", "https://example.com");
+  }
+
+  @Test
+  public void testRootRelativeUrl() {
+    check("https://example.com/dir/", "/resource", "https://example.com/resource");
+  }
+
+  @Test
+  public void testRelativePathWithDirectoryContext() {
+    check("https://example.com/dir/", "resource", "https://example.com/dir/resource");
+  }
+
+  @Test
+  public void testRelativePathWithFileContext() {
+    check("https://example.com/dir/file.html", "resource", "https://example.com/dir/resource");
+  }
+
+  @Test
+  public void testParentDirectoryNavigation() {
+    check("https://example.com/dir/subdir/", "../resource", "https://example.com/dir/resource");
+  }
+
+  @Test
+  public void testMultipleParentDirectoryNavigation() {
+    check("https://example.com/dir/subdir/", "../../resource", "https://example.com/resource");
+  }
+
+  @Test
+  public void testParentDirectoryNavigationWithFileContext() {
+    check(
+        "https://example.com/dir/subdir/file.html",
+        "../../resource",
+        "https://example.com/resource");
+  }
+
+  @Test
+  public void testBackslashes() {
+    check(
+        "https://example.org/",
+        "https://example\\.com/dir\\subdir\\resource",
+        "https://example/.com/dir/subdir/resource");
+  }
+
+  @Test
+  public void testEmptyRelativeUrl() {
+    check("https://example.com/dir/subdir/", "", "https://example.com/dir/subdir/");
+  }
+
+  @Test
+  public void testNullUrlFound() throws MalformedURLException {
+    checkNull(new URL("https://example.com/dir/"), null);
+  }
+
+  @Test
+  public void testNullContext() {
+    checkNull(null, "resource");
+  }
+
+  @Test
+  public void testInvalidContextFormatting() {
+    check("https:///test", "resource", "https:/resource");
+  }
+
+  @Test
+  public void testComplexRelativePath() {
+    check(
+        "https://example.com/dir/subdir/",
+        "../../subdir2/resource/../../file",
+        "https://example.com/subdir2/resource/../../file");
+  }
+
+  @Test
+  public void testAbsoluteUrlWithUpperCase() {
+    check(
+        "https://example.org/path/",
+        "HTTPS://EXAMPLE.COM/RESOURCE",
+        "https://example.com/resource");
+  }
+}