Improve code test coverage

docs/source/policies.rst

@@ -41,6 +41,6 @@ Simple Batch
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 This policy's behaviour is similar to the Simple policy but it will process files in batches instead
-of processing them all at once.
+of processing all the files at once.
 
 You can learn more about the properties of this policy :ref:`here<config_options-policies-simple_batch>`.

src/test/java/com/github/mmolimar/kafka/connect/fs/policy/SimpleBatchPolicyTest.java

@@ -12,6 +12,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
@@ -78,4 +79,17 @@ public void execPolicyBatchesFiles(PolicyFsTestConfig fsConfig) throws IOExcepti
         assertFalse(it.hasNext());
         assertTrue(fsConfig.getPolicy().hasEnded());
     }
+
+    @ParameterizedTest
+    @MethodSource("fileSystemConfigProvider")
+    public void invalidBatchSize(PolicyFsTestConfig fsConfig) {
+        Map<String, String> configMap = buildConfigMap(fsConfig.getDirectories());
+        configMap.put(SimpleBatchPolicy.BATCH_POLICY_BATCH_SIZE, "one");
+        FsSourceTaskConfig sourceTaskConfig = new FsSourceTaskConfig(configMap);
+        assertThrows(NumberFormatException.class, () -> {
+            ReflectionUtils.makePolicy((Class<? extends Policy>) fsConfig.getSourceTaskConfig()
+                    .getClass(FsSourceTaskConfig.POLICY_CLASS), sourceTaskConfig);
+        });
+
+    }
 }