CSVLineParserTest.java

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.runners.MockitoJUnitRunner;

import java.util.Arrays;
import java.util.List;

import static org.junit.Assert.*;
import static org.mockito.Mockito.when;

@RunWith(MockitoJUnitRunner.class) // This is to run with the MockitoJunitRunner instead of the default junit runner
public class CSVLineReaderTest {

    @Mock // This annotation means we are not using a real CSVLineReader object but we will mock it and the mock set up will happen in the init method
    CSVLineReader reader;
    CSVLineParser parser;

    @Before
    public void setUp() {
        parser = new CSVLineParser(reader);
    }

    @Test // Unit test 1
    public void testNoData() {
        when(reader.readCurrentLine()).thenReturn(null);
        List<String> ret = parser.parseCurrent();

        assertNotNull("Returned list shouldn't be null", ret);
        assertTrue("Returned list should be empty", ret.isEmpty());
    }

    @Test
    public void testParseEmptyLine() {
        when(reader.readCurrentLine()).thenReturn("");
        List<String> ret = parser.parseCurrent();

        assertNotNull("Returned list shouldn't be null", ret);
        assertTrue("Returned list should be empty", ret.isEmpty());
    }

    @Test
    public void testParseData1() {
        when(reader.readCurrentLine()).thenReturn("a,b,c,d");
        List<String> ret = parser.parseCurrent();

        assertNotNull("Returned list shouldn't be null", ret);
        assertEquals("Returned list should have 4 elements", ret.size(), 4);
        assertEquals("Returned list should be a,b,c,d", ret, Arrays.asList(new String[]{"a", "b", "c", "d"}));
    }

    @Test
    public void testParseData2() {
        when(reader.readCurrentLine()).thenReturn("a");
        List<String> ret = parser.parseCurrent();

        assertNotNull("Returned list shouldn't be null", ret);
        assertEquals("Returned list should have 1 element", ret.size(), 1);
        assertEquals("Returned list should be a,b,c,d", ret, Arrays.asList(new String[]{"a"}));
    }

    @Test
    public void testLongWordsData() {
        when(reader.readCurrentLine()).thenReturn("se7so,is,gamed,gedn,.");
        List<String> ret = parser.parseCurrent();

        assertNotNull("Returned list shouldn't be null", ret);
        assertEquals("Returned list should have 5 elements", ret.size(), 5);
        assertEquals("Returned list should be se7so,is,gamed,gedn", ret, Arrays.asList(new String[]{"se7so", "is", "gamed", "gedn", "."}));
    }

    @Test
    public void testOtherDelimiters() {
        when(reader.readCurrentLine()).thenReturn("foo-bar,foo,bar---");
        List<String> ret = parser.parseCurrent();

        assertNotNull("Returned list shouldn't be null", ret);
        assertEquals("Returned list should have 5 elements", ret.size(), 3);
        assertEquals("Returned list should be foo-bar,foo,bar---", ret, Arrays.asList(new String[]{"foo-bar", "foo", "bar---"}));
    }
}