Test folder created.

Axel/test/de/hs_mannheim/informatik/spreadsheet/SpreadsheetTest.java

@@ -0,0 +1,10 @@
+package de.hs_mannheim.informatik.spreadsheet;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class SpreadsheetTest {
+
+    @org.junit.jupiter.api.Test
+    void sum() {
+    }
+}

PR1-Spreadsheet.iml

@@ -4,6 +4,7 @@
     <exclude-output />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/Axel/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/Axel/test" isTestSource="true" />
     </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />