Remove AssertJ in favor of plain JUnit5

src/test/java/org/jabref/logic/layout/format/MarkdownFormatterTest.java

@@ -3,8 +3,10 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class MarkdownFormatterTest {
 
@@ -17,44 +19,48 @@ void setUp() {
 
     @Test
     void formatWhenFormattingPlainTextThenReturnsTextWrappedInParagraph() {
-        assertThat(markdownFormatter.format("Hello World")).isEqualTo("<p>Hello World</p>");
+        assertEquals("<p>Hello World</p>", markdownFormatter.format("Hello World"));
     }
 
     @Test
     void formatWhenFormattingComplexMarkupThenReturnsOnlyOneLine() {
         String source = "Markup\n\n* list item one\n* list item 2\n\n rest";
-        assertThat(markdownFormatter.format(source))
-                .contains("Markup<br />")
-                .contains("<li>list item one</li>")
-                .contains("<li>list item 2</li>")
-                .contains("> rest")
-                .doesNotContain("\n");
+
+        String actual = markdownFormatter.format(source);
+
+        // Only test relevant bits and ignore possible whitespace introduced by html-renderer
+        assertTrue(actual.contains("Markup<br />"));
+        assertTrue(actual.contains("<li>list item one</li>"));
+        assertTrue(actual.contains("<li>list item 2</li>"));
+        assertTrue(actual.contains("> rest"));
+        assertFalse(actual.contains("\n"));
     }
 
     @Test
     void formatWhenFormattingEmptyStringThenReturnsEmptyString() {
-        assertThat(markdownFormatter.format("")).isEqualTo("");
+        assertEquals("", markdownFormatter.format(""));
     }
 
     @Test
     void formatWhenFormattingNullThenThrowsException() {
-        assertThatExceptionOfType(NullPointerException.class).isThrownBy(() -> markdownFormatter.format(null))
-                                                             .withMessageContaining("Field Text should not be null, when handed to formatter")
-                                                             .withNoCause();
+        Exception exception = assertThrows(NullPointerException.class, () -> markdownFormatter.format(null));
+        assertEquals("Field Text should not be null, when handed to formatter", exception.getMessage());
     }
 
     @Test
     void formatWhenMarkupContainingStrikethroughThenContainsMatchingDel() {
-        assertThat(markdownFormatter.format("a ~~b~~ b")).contains("<del>b</del>");
+        // Only test strikethrough extension
+        assertTrue(markdownFormatter.format("a ~~b~~ b").contains("<del>b</del>"));
     }
 
     @Test
     void formatWhenMarkupContainingTaskListThenContainsFormattedTaskList() {
-        assertThat(markdownFormatter.format("Some text\n" +
+        String actual = markdownFormatter.format("Some text\n" +
                 "* [ ] open task\n" +
                 "* [x] closed task\n\n" +
-                "some other text"))
-                .contains("<li class=\"task-list-item\"><input type=\"checkbox\" class=\"task-list-item-checkbox\" disabled=\"disabled\" readonly=\"readonly\" />&nbsp;open task</li>")
-                .contains("<li class=\"task-list-item\"><input type=\"checkbox\" class=\"task-list-item-checkbox\" checked=\"checked\" disabled=\"disabled\" readonly=\"readonly\" />&nbsp;closed task</li>");
+                "some other text");
+        // Only test list items
+        assertTrue(actual.contains("<li class=\"task-list-item\"><input type=\"checkbox\" class=\"task-list-item-checkbox\" disabled=\"disabled\" readonly=\"readonly\" />&nbsp;open task</li>"));
+        assertTrue(actual.contains("<li class=\"task-list-item\"><input type=\"checkbox\" class=\"task-list-item-checkbox\" checked=\"checked\" disabled=\"disabled\" readonly=\"readonly\" />&nbsp;closed task</li>"));
     }
 }