Merge pull request AY2324S2-CS2103T-F12-2#249 from Howlong11/branch-e…

…-linkTest

test class for link class

src/main/java/seedu/address/model/article/Link.java

@@ -15,9 +15,9 @@ public class Link {
     public final String link;
 
     /**
-     * Constructs a {@code Title}.
+     * Constructs a {@code Link}.
      *
-     * @param link A valid title.
+     * @param link A valid link.
      */
     public Link(String link) {
         if (link == null) {

src/test/java/seedu/address/model/article/LinkTest.java

@@ -0,0 +1,80 @@
+package seedu.address.model.article;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static seedu.address.testutil.Assert.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class LinkTest {
+
+    @Test
+    public void constructor_null_createsEmptyLink() {
+        assertTrue(new Link("").equals(new Link(null)));
+    }
+
+    @Test
+    public void constructor_invalidLink_throwsIllegalArgumentException() {
+        String invalidLink = " ";
+        assertThrows(IllegalArgumentException.class, () -> new Link(invalidLink));
+    }
+
+    @Test
+    public void isValidLink() {
+        //null Link
+        assertThrows(NullPointerException.class, () -> Link.isValidLink(null));
+
+        // blank Link
+        assertTrue(Link.isValidLink("")); // empty string
+
+        // whitespaces only
+        assertFalse(Link.isValidLink(" ")); // space only
+        assertFalse(Link.isValidLink("  ")); // multiple spaces only
+
+        // whitespaces in Link
+        assertTrue(Link.isValidLink("mylink ")); // trailing space
+        assertTrue(Link.isValidLink("mylink  ")); // multiple trailing spaces
+        assertTrue(Link.isValidLink("my link")); // middle space
+        assertTrue(Link.isValidLink("my  link")); // multiple middle spaces
+
+        // invalid Links
+        assertFalse(Link.isValidLink(" mylink")); // leading space
+        assertFalse(Link.isValidLink("  mylink")); // multiple leading spaces
+
+        // valid Links
+        assertTrue(Link.isValidLink("mylink")); // alphabets only
+        assertTrue(Link.isValidLink("12345")); // numbers only
+        assertTrue(Link.isValidLink("my link")); // alphabets with space
+        assertTrue(Link.isValidLink("123 45")); // numbers with space
+        assertTrue(Link.isValidLink("my link 123")); // alphanumeric with spaces
+        assertTrue(Link.isValidLink("~!@#$%^&*()_+`-={}|[]:,.?/;" + "\"")); // special characters only
+        assertTrue(Link.isValidLink("~!@#$%^&* ()_+`-={}|[]:,.?/;" + " \"")); // special characters with spaces
+        assertTrue(Link.isValidLink("my link: 123")); // alphanumeric with special characters and spaces
+        assertTrue(Link.isValidLink("my link: 123 ")); // alphanumeric with special characters and trailing space
+        assertTrue(Link.isValidLink("试试看")); // non-english unicode characters
+        assertTrue(Link.isValidLink("试试 看")); // non-english unicode characters with space
+        assertTrue(Link.isValidLink("试试看 123")); // non-english unicode characters with numbers and space
+        assertTrue(Link.isValidLink("试试看: #123@")); // unicode characters with special characters, and spaces
+        assertTrue(Link.isValidLink("试试看: #123@ ")); // mixed unicode characters with trailing space
+    }
+
+    @Test
+    public void equals() {
+        Link link = new Link("my link");
+
+        // same values -> returns true
+        assertTrue(link.equals(new Link("my link")));
+
+        // same object -> returns true
+        assertTrue(link.equals(link));
+
+        // null -> returns false
+        assertFalse(link.equals(null));
+
+        // different types -> returns false
+        assertFalse(link.equals(5.0f));
+
+        // different link -> returns false
+        assertFalse(link.equals(new Link("not my link")));
+    }
+}