powermock : ProcessBuilder redirectErrorStream giving nullPointerException
- by kaustubh9
I am using powermock to mock some native command invocation using process builder. the strange thing is these test pass sometimes and fail sometimes giving a NPE. Is this a powermock issue or some gotcha in the program.
the snippet of the class under test is..
public void method1(String jsonString, String filename) {
try {
JSONObject jObj = new JSONObject(jsonString);
JSONArray jArr = jObj.getJSONArray("something");
String cmd = "/home/y/bin/perl <perlscript>.pl<someConstant>" + " -k " + <someConstant> + " -t " + <someConstant>;
cmd += vmArr.getJSONObject(i).getString("jsonKey");
ProcessBuilder pb = new ProcessBuilder("bash", "-c", cmd);
pb.redirectErrorStream(false);
Process shell = pb.start();
shell.waitFor();
if (shell.exitValue() != 0) {
throw new RuntimeException("Error in Collecting the logs. cmd="+cmd);
}
StringBuilder error =
new StringBuilder();
InputStream iError = shell.getErrorStream();
BufferedReader bfr =
new BufferedReader(
new InputStreamReader(iError));
String line = null;
while ((line = bfr.readLine()) != null) {
error.append(line + "\n");
}
if (!error.toString().isEmpty()) {
LOGGER.error(error`enter code here`);
}
iError.close();
bfr.close();
} catch (Exception e) {
throw new RuntimeException(e);
}
and the unit test case is ..
@PrepareForTest( {.class, ProcessBuilder.class,Process.class, InputStream.class,InputStreamReader.class, BufferedReader.class} )
@Test(sequential=true)
public class TestClass {
@Test(groups = {"unit"})
public void testMethod() {
try {
ProcessBuilder prBuilderMock = createMock(ProcessBuilder.class);
Process processMock = createMock(Process.class);
InputStream iStreamMock = createMock(InputStream.class);
InputStreamReader iStrRdrMock = createMock(InputStreamReader.class);
BufferedReader bRdrMock = createMock(BufferedReader.class);
String errorStr =" Error occured";
String json = <jsonStringInput>;
String cmd = "/home/y/bin/perl <perlscript>.pl -k "+<someConstant>+" -t "+<someConstant>+" "+<jsonValue>;
expectNew(ProcessBuilder.class, "bash", "-c", cmd).andReturn(prBuilderMock);
expect(prBuilderMock.redirectErrorStream(false)).andReturn(prBuilderMock);
expect(prBuilderMock.start()).andReturn(processMock);
expect(processMock.waitFor()).andReturn(0);
expect(processMock.exitValue()).andReturn(0);
expect(processMock.getErrorStream()).andReturn(iStreamMock);
expectNew(InputStreamReader.class, iStreamMock)
.andReturn(iStrRdrMock);
expectNew(BufferedReader.class, iStrRdrMock)
.andReturn(bRdrMock);
expect(bRdrMock.readLine()).andReturn(errorStr);
expect(bRdrMock.readLine()).andReturn(null);
iStreamMock.close();
bRdrMock.close();
expectLastCall().once();
replayAll();
<ClassToBeTested> instance = new <ClassToBeTested>();
instance.method1(json, fileName);
verifyAll();
} catch (Exception e) {
Assert.fail("failed while collecting log.", e);
}
}
I get an error on execution an the test case fails..
Caused by: java.lang.NullPointerException
at java.lang.ProcessBuilder.start(ProcessBuilder.java:438)
Note : I do not get this error on all executions. Sometimes it passes and sometimes it fails. I am not able to understand this behavior.
