NullPointerException when toString() of parameter returns null

[PascalSchumacher]

Hi,

thanks for providing junit-dataprovider.

While working on a pull request to switch assertj from JUnitParams to junit-dataprovider I encountered the this problem.

When I try to use null as a parameter, e.g.:

  @DataProvider()
  public static Object[][] testDescriptionGenerator() {
    return new Object[][] {
        { new TestDescription(null) }
  }

  @Test
  @UseDataProvider("testDescriptionGenerator")
  public void should_return_empty_String(TestDescription testDescription) {
    assertThat(formatter.format(testDescription)).isEmpty();
  }

I get

java.lang.NullPointerException
    at com.tngtech.java.junit.dataprovider.internal.placeholder.ParameterPlaceholder.format(ParameterPlaceholder.java:99)
    at com.tngtech.java.junit.dataprovider.internal.placeholder.ParameterPlaceholder.formatAll(ParameterPlaceholder.java:70)
    at com.tngtech.java.junit.dataprovider.internal.placeholder.ParameterPlaceholder.getReplacementFor(ParameterPlaceholder.java:57)
    at com.tngtech.java.junit.dataprovider.internal.placeholder.BasePlaceholder.process(BasePlaceholder.java:61)
    at com.tngtech.java.junit.dataprovider.DataProviderFrameworkMethod.getName(DataProviderFrameworkMethod.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.testName(BlockJUnit4ClassRunner.java:225)
    at org.junit.runners.BlockJUnit4ClassRunner.describeChild(BlockJUnit4ClassRunner.java:96)
    at org.junit.runners.BlockJUnit4ClassRunner.describeChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner.getDescription(ParentRunner.java:352)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createUnfilteredTest(JUnit4TestLoader.java:85)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:70)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:43)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:444)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

Because in this case TestDescription#toString returns null. Not sure if this is something that junit-dataprovider should handle?

[aaschmid]

Hi @PascalSchumacher, the problem is really that TestDescription#toString() returns null as the junit-dataprovider ParameterPlaceholder line 93 to 99 are

        String result;
        if (param instanceof String) {
            result = (String) param;
        } else {
            result = param.toString();
        }
        return result.replaceAll("\\r", "\\\\r").replaceAll("\\n", "\\\\n");

I will fix it in a moment :-)
Thanks for reporting this!

[aaschmid]

Is it somehow urgent? I can provide you a snapshot version to retest if you want. Otherwise I can create a new release hopefully before christmas. What would you prefer @PascalSchumacher?

[aaschmid]

Btw. second commit suppresses findbugs warning because findbugs assumes that toString() does not return null :-S

[PascalSchumacher]

Thanks for the ultra quick fix. 👍

Yes, returning null from toString() is not a good practice.

Is it somehow urgent? I can provide you a snapshot version to retest if you want. Otherwise I can >create a new release hopefully before christmas. What would you prefer @PascalSchumacher?

Thanks for the offer, but it's not urgent so I'm fine with waiting.