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Balta

Balta makes testing DB entities from Scala easier. It's primarily focused on testing the behavior of Postgres functions.

Build Status

Build

Maven Central

Balta is a Scala library to help creating database tests, particularly testing Database functions. It is based on the popular ScalaTest library and uses PostgreSQL as the database engine.

It's a natural complement to the use of Fa-Db library in applications.

Expected test-case structure

  1. Transaction start*
  2. Insert needed data into tables
  3. Call the function to be tested
  4. Verify the return values of the function via the verify function provided
  5. Verify the data un the tables
  6. Transaction rollback*
  • The transaction start and rollback are done automatically before or after the execution respectively of the test function provided

Advantages of this approach is that the tests are repeatable, they are isolated from each other and the database is always in a known state before and after each test.

How to write tests

DBTestSuite class

The foundation is the DBTestSuite class that provides the necessary setup and teardown for the tests to each run in its own transaction. It is an enhancement class to standard ScalaTest AnyFunSuite class.

Besides that, it provides easy access to tables, queries them and inserts data into them.

And it allows easy access to database functions and executing them.

DBTable class

Class for representing a database table. It provides methods for querying the table and inserting data into it. The class instance is spawned by each DBTestSuite.table method call.

DBFunction class

Class for representing a database function. It provides methods for calling the function and verifying the return values. The class instance is spawned by each DBTestSuite.function method call.

QueryResult class

This iterator represents the result of a query. It provides methods for iterating over the rows and columns of the result.

QueryResultRow class

This class represents a row in a query result. It provides methods for accessing the columns of the row - via name or index.

To make specific Postgres types available in QueryResultRow there is the implicit class Postgres.PostgresRow enhancing the QueryResultRow with the ability to get type like JSON (including JSONB) and JSON[] (JSON array).

There is also an implicit class QueryResultImplicits.ProductTypeConvertor enhancing the QueryResultRow with the ability to convert the row to a product type (case class or tuple) via function toProductType[T].

How to test the library

Use the test command to execute all unit tests, skipping all other types of tests.

sbt test

There are integration tests part of the package that can be run with the following command:

sbt testIT

If you want to run all tests, use the following command.

sbt testAll

The integrations tests to finish successfully, a Postgres database must be running and populated.

  • by default the database is expected to be running on localhost:5432
  • if you wish to run against a different server modify the src/test/resources/database.properties file
  • to populate the database run the scripts in the src/test/resources/db/postgres folder

How to generate JaCoCo code coverage report

Run the following command from path {project-root}

sbt jacoco

Report should be available on path {project-root}/balta/target/scala-2.12/jacoco/report/html

How to Release

Please see this file for more details.

Known Issues

Postgres

  • TIMESTAMP WITH TIME ZONE[], TIME WITH TIME ZONE[], generally arrays of time related types are not translated to appropriate time zone aware Scala/Java types
  • Conversion to product type won't work if there are complex members in the product type like subclasses; with container types like List, it hasn't been tested