package test.string;

import java.lang.String;
import static org.junit.Assert.assertThat;
import org.junit.Test;

public class StringFormatTestCase {
    @Test
    public void testNumberFormattingWithLeadingZeros() {
        final String formatted = String.format("%04d", 1);
        assertThat(formatted, equalTo("0001"));
    }

    @Test
    public void testDoubleFormattingWithTwoDecimalPoints() {
        final String formatted = String.format("%.2f", 12.324234d);
        assertThat(formatted, equalTo("12.32"));
    }
}

Errors

Error:(3, 33) java: package org.junit does not exist
Error:(3, 2) java: static import only from classes and interfaces
Error:(5, 25) java: package org.junit does not exist
Error:(6, 12) java: package org.junit does not exist
Error:(12, 10) java: cannot find symbol
    symbol:   class Before
    location: class edu.kit.ipd.swt1.StringFormatTestCase 
    Error:(17, 11) java: cannot find symbol
[...]

In order to fix it we had to Open Module Settings for that project and manually add jar Dependencies junit-4.12.jar and hamcrest-core-1.3.jar which are contained in the IntelliJ installation lib directory (C://Program Files/JetBrains/lib/xxx.