Package io.debezium.embedded

Class ConnectorOutputTest

java.lang.Object
io.debezium.embedded.ConnectorOutputTest
Direct Known Subclasses:
SimpleSourceConnectorOutputTest
public abstract class ConnectorOutputTest extends Object
A base class for classes the define integration tests for connectors that verify the output of a connector matches an expected sequence of change event records. This base class provides a simple framework for running a connector given a configuration and either recording or comparing the connector's output to expected results.

Overview

One of the common and easiest ways to test a connector is to simply run it and compare the changes events output by the connector with a sequence of expected change events. Manually writing tests to compare the results is tedious and error prone, so an alternative is to run the test once and record the change events output by the connector so that these change events can be used as expected results in subsequent runs of the same test.

This framework makes it possible to define tests that start a connector, record the change events output by the connector, and compare these change events to expected results. Connectors are defined via properties files, and the expected results are recorded to or read from files containing the sequence of change events serialized as an array of JSON documents. The test can also define an optional environment properties file in which test-specific parameters can be specified.

Variations in results

Some fields in the output will change every time the connector is run. For example, a change event may include the timestamp at which the connector processed/generated the event, or it might include a transaction identifier that is different with each run. The framework works around these issues by allowing the test to specify in the environment parameters the fields in the change events that should be ignored when comparing actual change events to expected change events.

Other fields may vary every time the database is started. For example, a MySQL server that is configured to use GTIDs will generate a new server_uuid value when it is initialized, and this value is then used in all GTIDs generated by that server instance. Since multiple builds will start up and initialize a new MySQL server (in a Docker container), the GTID will vary with each build. The framework can handle this by allowing the expected results to contain variables in the form of ${variableName1}, and the framework will use values supplied during test setup to replace these variables prior to parsing the JSON document for each expected change event. The framework allows the test setup to supply a function that provides the replacement variable values given the connector configuration. So the MySQL connector tests, for example, can connect to the MySQL server and return all of the system variables as the variable values; the framework does all the rest.

Stopping the connector

When the test framework has compared all of the generated change events to the expected change events and found no discrepancies, the framework knows that the connector should generate no additional change events. If the connector does generate another event, the test will fail. Otherwise, the framework will stop the connector since it is no longer needed.

Connector restarts

Another requirement is to verify that a connector will resume where it left off when it is restarted following a failure or graceful shutdown. This is normally a bit harder to do, but this framework makes it very easy. Simply insert in the sequence of expected change events a restart command. The framework consumes each change event generated by the connector one at a time, and for each it compares it to the expected change event. As the framework comes across a restart command in the expected results, it knows to stop the connector (persisting the offsets in the last change event processed by the connector) and to then restart it given those persisted offsets. A properly-written connector will resume exactly where it left off, and the framework can once again begin comparing the resulting change events to the next events in the expected results.

Example

A simple test runs a connector and records/compares the connector's output to expected results: 
 @Test
 public void shouldCaptureChangesFromMySqlWithNoGtids() {
     runConnector(usingSpec("test1", "src/test/resources/expected/test1"));
 }
The framework uses a test specification that encapsulates the connector configuration, the environment properties, how to obtain the variable values, and where to find the results. This example creates a test specification with the name test1 and the connector properties file, the environment properties file, and the expected results file all defined in a directory named src/test/resources/expected/test1. Once again, the test will write out the expected results file if none exists; otherwise, it will read in the expected results and compare them to the events output by the connector.

The framework supports other variations, and the specWith method is a simple convenience method that replaces explicitly building up the test specification by using lots of defaults. Consequently, the framework offers a great deal of flexibility.

To see more detail about the actual and expected records, turn on Debezium's test debug mode by using this line before the runConnector call: 

 Testing.Debug.enable();
Author:
Randall Hauch

  • Field Details

  • Constructor Details

    • ConnectorOutputTest

      public ConnectorOutputTest()

  • Method Details

    • addValueComparatorsByFieldPath

      protected void addValueComparatorsByFieldPath(BiConsumer<String,VerifyRecord.RecordValueComparator> comparatorsByPath)

    • addValueComparatorsBySchemaName

      protected void addValueComparatorsBySchemaName(BiConsumer<String,VerifyRecord.RecordValueComparator> comparatorsByPath)

    • usingSpec

      protected ConnectorOutputTest.TestSpecification usingSpec(String name)
      Create a new test specification with the given name.
      Parameters:
      name - the name of the test
      Returns:
      the test specification; never null

    • usingSpec

      protected ConnectorOutputTest.TestSpecification usingSpec(String name, String directory)
      Create a new test specification that uses the files in the given directory for the connector configuration, environment configuration, and expected results. These names of these files are as follows:
      Parameters:
      name - the name of the test
      directory - the path to the directory that contains the test files; may not be null
      Returns:
      the test specification; never null

    • usingSpec

      protected ConnectorOutputTest.TestSpecification usingSpec(String name, Path directory)
      Create a new test specification that uses the files in the given directory for the connector configuration, environment configuration, and expected results. These names of these files are as follows:
      Parameters:
      name - the name of the test
      directory - the path to the directory that contains the test files; may not be null
      Returns:
      the test specification; never null

    • usingSpec

      protected ConnectorOutputTest.TestSpecification usingSpec(String name, String configFile, String expectedRecordsFile, String envFile)
      Create a new test specification that uses the given files for the configuration, environment, and expected results.
      Parameters:
      name - the name of the test or test run; may not be null
      configFile - the path to the configuration file; may not be null
      expectedRecordsFile - the path to the file where the expected records can be read or where they are to be written; may not be null
      envFile - the path to the file containing the environment properties; may be null if there is no such file
      Returns:
      the test specification; never null

    • usingSpec

      protected ConnectorOutputTest.TestSpecification usingSpec(String name, Path configFile, Path expectedRecordsFile, Path envFile)
      Create a new test specification that uses the given files for the configuration, environment, and expected results.
      Parameters:
      name - the name of the test or test run; may not be null
      configFile - the path to the configuration file; may not be null
      expectedRecordsFile - the path to the file where the expected records can be read or where they are to be written; may not be null
      envFile - the path to the file containing the environment properties; may be null if there is no such file
      Returns:
      the test specification; never null

    • cleanOffsetStorage

      public void cleanOffsetStorage()

    • afterEachTestMethod

      public void afterEachTestMethod()

    • globallyIgnorableFieldNames

      protected String[] globallyIgnorableFieldNames()
      Return the names of the fields that should always be ignored for all tests. By default this method returns null.
      Returns:
      the array of field names that should always be ignored, or empty or null if there are no such fields

    • runConnector

      protected void runConnector(String testName, String directory)
      Run the connector that uses the files in the given directory for the connector configuration, environment configuration, and expected results. These names of these files are as follows:
      Parameters:
      testName - the name of the test or test run; may not be null
      directory - the path to the directory that contains the test files; may not be null

    • runConnector

      protected void runConnector(String testName, Path directory)
      Run the connector that uses the files in the given directory for the connector configuration, environment configuration, and expected results. These names of these files are as follows:
      Parameters:
      testName - the name of the test or test run; may not be null
      directory - the path to the directory that contains the test files; may not be null

    • runConnector

      protected void runConnector(String testName, String configFile, String expectedRecordsFile, String envFile)
      Run the connector described by the supplied test specification.
      Parameters:
      testName - the name of the test or test run; may not be null
      configFile - the path to the configuration file; may not be null
      expectedRecordsFile - the path to the file where the expected records can be read or where they are to be written; may not be null
      envFile - the path to the file containing the environment properties; may be null if there is no such file

    • runConnector

      protected void runConnector(String testName, Path configFile, Path expectedRecordsFile, Path envFile)
      Run the connector described by the supplied test specification.
      Parameters:
      testName - the name of the test or test run; may not be null
      configFile - the path to the configuration file; may not be null
      expectedRecordsFile - the path to the file where the expected records can be read or where they are to be written; may not be null
      envFile - the path to the file containing the environment properties; may be null if there is no such file

    • runConnector

      protected void runConnector(ConnectorOutputTest.TestSpecification spec)
      Run the connector described by the supplied test specification.
      Parameters:
      spec - the test specification

    • runConnector

      protected void runConnector(ConnectorOutputTest.TestSpecification spec, io.debezium.embedded.EmbeddedEngine.CompletionCallback callback)
      Run the connector described by the supplied test specification.
      Parameters:
      spec - the test specification
      callback - the function that should be called when the connector is stopped

    • applyCommand

      private void applyCommand(Document record, ConnectorOutputTest.ConsumerCompletion result)

    • isCommand

      private boolean isCommand(Document record)

    • isEndCommand

      private boolean isEndCommand(Document record)

    • getCommand

      private String getCommand(Document record)

    • rehydrateSourceRecord

      private org.apache.kafka.connect.source.SourceRecord rehydrateSourceRecord(Document record, ConnectorOutputTest.SchemaAndValueConverter keyConverter, ConnectorOutputTest.SchemaAndValueConverter valueConverter) throws IOException
      Throws:
      IOException

    • serializeSourceRecord

      private Document serializeSourceRecord(org.apache.kafka.connect.source.SourceRecord record, ConnectorOutputTest.SchemaAndValueConverter keyConverter, ConnectorOutputTest.SchemaAndValueConverter valueConverter) throws IOException
      Serialize the source record to document form.
      Parameters:
      record - the record; may not be null
      keyConverter - the converter for the record key's schema and payload
      valueConverter - the converter for the record value's schema and payload
      Returns:
      the document form of the source record; never null
      Throws:
      IOException - if there is an error converting the key or value

    • assertSourceRecordMatch

      private void assertSourceRecordMatch(org.apache.kafka.connect.source.SourceRecord actual, org.apache.kafka.connect.source.SourceRecord expected, Predicate<String> ignoreFields, Map<String,VerifyRecord.RecordValueComparator> comparatorsByName, Map<String,VerifyRecord.RecordValueComparator> comparatorsBySchemaName)

    • toMap

      private Map<String,?> toMap(Document doc)

    • fixedSizeQueue

      private <T> Queue<T> fixedSizeQueue(int size)

    • replaceVariables

      protected static File replaceVariables(InputStream stream, AvailableVariables variables) throws IOException
      Read the contents of the supplied InputStream, replace all variables found in the content, and write the result to a temporary file.
      Parameters:
      stream - the input stream containing zero or more variable expressions
      variables - the variables
      Returns:
      the temporary file that exists in the data directory
      Throws:
      IOException - if there is a problem reading the input stream or writing to the temporary file