What are dbt tests and how do you use them?

dbt tests are declarative assertions in dbt that automatically validate data quality during model builds.

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Description

dbt tests

dbt tests are assertions written in YAML or SQL that validate data quality and integrity during dbt runs, catching nulls, duplicates, and business rule violations early.

What Are dbt tests?

dbt tests assert expected conditions on tables or columns.During dbt test runs, dbt materializes each assertion as a query and returns PASS or FAIL, giving immediate feedback on data quality.

Why Use dbt tests in Data Pipelines?

Automated tests surface bad data at build time, preventing flawed downstream analytics. They act like unit tests for SQL models, enabling continuous delivery and trusted dashboards.

How Do You Write a dbt test?

Add a YAML block under models: or create a SQL test macro.dbt converts the configuration to a SELECT statement that returns failing rows.

Example: Generic dbt schema test

# models/my_model.yml
version: 2
models:
- name: my_model
columns:
- name: id
tests:
- unique
- not_null

What Are Common dbt test Types?

Generic tests ship with dbt: unique, not_null, accepted_values, and relationships. Custom tests allow bespoke SQL logic for complex business rules.

How Do dbt tests Run in CI/CD?

Include dbt test after dbt build in GitHub Actions or GitLab CI.Fail the pipeline when any test fails to block bad data from production.

What Are Best Practices for dbt tests?

Start with generic tests on primary keys and foreign keys. Promote critical custom tests to staging.Tag tests (e.g., severity: error) for selective runs in CI.

How Does Galaxy Enhance dbt testing?

Galaxys SQL editor autocompletes dbt YAML and SQL test macros, highlights failing test queries, and lets teams share endorsed test snippets in Collections for reuse.

What Are Limitations and Pitfalls of dbt tests?

Tests run post-build, so they cant prevent bad data load. Heavy custom tests may slow pipelines.Always index columns used in tests to avoid warehouse cost spikes.

Key Takeaways

dbt tests are lightweight, version-controlled data quality checks that slot seamlessly into CI/CD. Generic tests cover basics; custom tests guard business rules. Tools like Galaxy make authoring and sharing tests faster.

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Why dbt tests is important

Data teams rely on fresh, correct datasets. Without automated validation, silent data errors can cascade into reports and decisions. dbt tests give engineers declarative, version-controlled assertions that fail fast, ensuring trust and enabling continuous deployment pipelines.

dbt tests Example Usage


How do I ensure the id column is unique and not null in dbt?

dbt tests Syntax



Common Mistakes

Frequently Asked Questions (FAQs)

How do generic and custom dbt tests differ?

Generic tests are parameterized macros shipped with dbt; custom tests are SQL files that house bespoke assertions.

Can I skip certain tests in production?

Yes. Use tags and the --select or --exclude flags to run only critical tests in prod.

How does Galaxy relate to dbt tests?

Galaxys editor autocompletes test macros, lets teams endorse trusted tests, and highlights failing rows for quick debugging.

What warehouses does dbt testing support?

All warehouses supported by dbt—Snowflake, BigQuery, Redshift, Databricks, and more—run tests natively because tests compile to SQL.

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