Add ControlHelper truncateString tests comments

src/test/java/org/jabref/gui/util/ControlHelperTest.java

@@ -0,0 +1,59 @@
+package org.jabref.gui.util;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.NullAndEmptySource;
+import org.junit.jupiter.params.provider.NullSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class ControlHelperTest {
+
+    private final String TEXT = "abcdef";
+    private final int MAX_CHARACTERS = 5;
+    private final int DEFAULT_MAX_CHARACTERS = -1;
+    private final String ELLIPSIS_STRING = "***";
+    private final ControlHelper.EllipsisPosition ELLIPSIS_POSITION = ControlHelper.EllipsisPosition.ENDING;
+
+    @ParameterizedTest
+    @NullAndEmptySource
+    void truncateWithTextNullAndEmptyReturnsSource(String text) {
+        String truncatedText = ControlHelper.truncateString(text, MAX_CHARACTERS, ELLIPSIS_STRING, ELLIPSIS_POSITION);
+        assertEquals(text, truncatedText);
+    }
+
+    @Test
+    void truncateWithDefaultMaxCharactersReturnsText() {
+        String truncatedText = ControlHelper.truncateString(TEXT, DEFAULT_MAX_CHARACTERS, ELLIPSIS_STRING, ELLIPSIS_POSITION);
+        assertEquals(TEXT, truncatedText);
+    }
+
+    @Test
+    void truncateWithEllipsisPositionBeginningReturnsTruncatedText() {
+        String truncatedText = ControlHelper.truncateString(TEXT, MAX_CHARACTERS, ELLIPSIS_STRING, ControlHelper.EllipsisPosition.BEGINNING);
+        assertEquals("***ef", truncatedText);
+    }
+
+    @Test
+    void truncateWithEllipsisPositionCenterReturnsTruncatedText() {
+        String truncatedText = ControlHelper.truncateString(TEXT, MAX_CHARACTERS, ELLIPSIS_STRING, ControlHelper.EllipsisPosition.CENTER);
+        assertEquals("a***f", truncatedText);
+    }
+
+    @Test
+    void truncateWithDefaultMaxCharactersAndNullEllipsisAndPositionEndingReturnsTruncatedText() {
+        String text = "a".repeat(75) + "b".repeat(25);
+        String truncatedText = ControlHelper.truncateString(text, DEFAULT_MAX_CHARACTERS, null, ControlHelper.EllipsisPosition.ENDING);
+        assertEquals("a".repeat(75), truncatedText);
+    }
+
+    @ParameterizedTest
+    @NullSource
+    void truncateWithNullEllipsisPositionThrowsNullPointerException(ControlHelper.EllipsisPosition ellipsisPosition) {
+        assertThrows(
+            NullPointerException.class,
+            () -> ControlHelper.truncateString(TEXT, MAX_CHARACTERS, ELLIPSIS_STRING, ellipsisPosition)
+        );
+    }
+}