public TestRunner addConfig(String key, String value) {
    Preconditions.checkNotNull(key);
    Preconditions.checkNotNull(value);
    configs.put(key, value);
    return this;
  }
Adds a config to Samza application. This config takes precedence over default configs and descriptor generated configs

@param key of the config
@param value of the config
@return this {@link TestRunner}
samza-test/src/main/java/org/apache/samza/test/framework/TestRunner.java