protected List<LogArgs> verifyLogCalls(final int callCount) {
        Mockito.verify(getMockErrorReceiver(), Mockito.times(callCount)).log(
                severityCaptor.capture(),
                locationCaptor.capture(),
                elementIdCaptor.capture(),
                messageCaptor.capture(),
                throwableCaptor.capture());

        if (callCount == 0) {
            return Collections.emptyList();
        } else {
            final List<LogArgs> logArgsList = new ArrayList<>();
            for (int i = 0; i < callCount; i++) {
                final LogArgs logArgs = new LogArgs(
                        severityCaptor.getAllValues().get(i),
                        locationCaptor.getAllValues().get(i),
                        elementIdCaptor.getAllValues().get(i),
                        messageCaptor.getAllValues().get(i),
                        throwableCaptor.getAllValues().get(i));
                LOGGER.debug("log called with args: {}", logArgs);
                logArgsList.add(logArgs);
            }
            return logArgsList;
        }
    }
Assert the number of times {@link ErrorReceiver#log(Severity, Location, String, String, Throwable)}
is called and get all the call args.

@param callCount Expected number of calls
@return All args used in the calls
stroom-pipeline/src/test/java/stroom/pipeline/xsltfunctions/AbstractXsltFunctionTest.java