Testing Configuration Loading

Testing configuration loading ensures that the Liquibase ClickHouse extension correctly parses and validates cluster-specific settings required for replicated environments. This process verifies that the system can distinguish between a single-instance setup and a multi-node cluster configuration by loading parameters from external .conf files.

The testing suite specifically targets the ParamsLoader utility to confirm it correctly populates the ClusterConfig data structure or gracefully handles malformed configuration files.

Sources: src/main/java/liquibase/ext/clickhouse/params/ParamsLoader.java, src/test/java/liquibase/ParamsLoaderTest.java

Configuration Architecture

The configuration loading system utilizes the Typesafe Config library to read HOCON-formatted files. It looks for a specific cluster block containing parameters for cluster naming and ZooKeeper paths.

Component Interaction

The following diagram illustrates the flow from a test case through the loader to the final configuration object:

The ParamsLoader acts as a static utility that abstracts the complexity of file I/O and validation, providing a clean ClusterConfig object to the rest of the extension.

Sources: src/main/java/liquibase/ext/clickhouse/params/ParamsLoader.java:79-111, src/test/java/liquibase/ParamsLoaderTest.java:27-40

Validation Logic

The system enforces a strict set of required properties. If any property is missing or if unknown properties are present, the loader logs a severe error and reverts to single-instance mode by returning null.

Required Properties

Sources: src/main/java/liquibase/ext/clickhouse/params/ParamsLoader.java:40-42, src/main/java/liquibase/ext/clickhouse/params/ClusterConfig.java:25-50

Failure Handling

When a configuration file is "broken" (e.g., contains typos in key names), the ParamsLoader catches InvalidPropertiesFormatException or ConfigException.Missing.

Implementation Details

Successful Load Example

A valid configuration file must match the expected structure precisely to be accepted by the test suite.

cluster {
    clusterName="Cluster1"
    tableZooKeeperPathPrefix="Path1"
    tableReplicaName="Replica1"
}

Sources: src/test/resources/testLiquibaseClickhouse.conf:1-6

Test Assertions

The ParamsLoaderTest class performs functional validation by asserting the state of the returned ClusterConfig object.

@Test
void loadParams() {
  ClusterConfig params = ParamsLoader.getLiquibaseClickhouseProperties("testLiquibaseClickhouse");
  assert (params != null);
  assert (params.getClusterName().equals("Cluster1"));
  assert (params.getTableZooKeeperPathPrefix().equals("Path1"));
  assert (params.getTableReplicaName().equals("Replica1"));
}

Sources: src/test/java/liquibase/ParamsLoaderTest.java:30-36

Integration with Liquibase Operations

While ParamsLoaderTest focuses on the unit level, the loaded configuration impacts how SQL is generated across the extension. When properties are found, the extension switches from standard MergeTree engines to ReplicatedMergeTree and appends ON CLUSTER clauses to DDL statements.

Sources: src/main/java/liquibase/ext/clickhouse/params/ParamsLoader.java:99-101, src/test/java/liquibase/ClickHouseTest.java:43-50

Conclusion

Testing configuration loading is critical for ensuring the extension's reliability in distributed ClickHouse environments. By validating the ParamsLoader against both valid and malformed files, the project ensures that cluster-mode features are only activated when a complete and correct configuration is provided, preventing runtime errors during database migrations.