NullPointerException in Java Test when you Read a File

This class reads a file CSV.

public class ReadCSVFile {

    private static final String SEMICOLON_DELIMITER = ";";


    public Map<Integer,Company> listFromFile(String csvFile) throws IOException {

        BufferedReader br = null;

        br = new BufferedReader(new 
        InputStreamReader(ReadCSVFile.class.getResourceAsStream(csvFile)));

        Map<Integer,Company> companyHashMap = new HashMap();

        String line;

        br.readLine();

        while ((line = br.readLine()) != null) {

            int pos = line.indexOf(SEMICOLON_DELIMITER);
            String companyCode = line.substring(0,pos);
            String companyName = line.substring(pos +1, line.length());

            companyHashMap.put(Integer.parseInt(companyCode), new Company(Integer.parseInt(companyCode), companyName));
        }

        return companyHashMap;
    }
}

This is the test for the class ReadCSVFile:

public class ReadCSVFileTest {

private ReadCSVFile readCSVFile;

@Before
public void before(){

    readCSVFile = new ReadCSVFile();
}

@Test
public void shouldExtractCompanyFromCSV() throws IOException {

    Map<Integer, Company> result = readCSVFile.listFromFile("test_company_list.csv");
    Assert.assertEquals(2,result.size());
    Assert.assertEquals("Goldman Sachs Group Inc",result.get(65).getCompanyName());
    Assert.assertEquals("Repsol YPF SA (Please refer to Repsol SA and YPF SA)",result.get(66).getCompanyName());
}

at the end this is the file to read test_company_list.csv and that I used to compare the result of the test:

 RepRisk Company ID;Company Name
65;Goldman Sachs Group Inc
66;Repsol YPF SA (Please refer to Repsol SA and YPF SA)

The test fails, I have this message:

java.lang.NullPointerException
    at java.io.Reader.<init>(Reader.java:78)
    at java.io.InputStreamReader.<init>(InputStreamReader.java:72)
    at app.ReadCSVFile.listFromFile(ReadCSVFile.java:21)
    at ReadCSVFileTest.shouldExtractCompanyFromCSV(ReadCSVFileTest.java:23)

What is wrong in my program? I think JUnit is correct as set up.

The line ReadCSVFile.java:21is this one:

br = new BufferedReader(new InputStreamReader(ReadCSVFile.class.getResourceAsStream(csvFile)));

instead the line (ReadCSVFileTest.java:23):

 Map<Integer, Company> result = readCSVFile.listFromFile("test_company_list.csv");