dbt tests are assertions to validate data models, ensuring data quality and integrity. There are two main types of dbt tests: generic and custom. Generic tests are pre-built tests defined in schema.yml for common data quality checks, while custom tests are developed to validate specific business logic or project-specific validation rules. Custom tests require more complex SQL queries and can be reused across models. Singular tests are standalone SQL queries that enforce rules not tied to a particular column and are used to ensure data integrity or enforce business rules. Unit tests validate the correctness of complex transformations or logic within models, isolating specific logic for validation. dbt tests fit into CI/CD pipelines, ensuring data reliability at every step, and can be automated with tools like Metaplane's dbt alerting tool. Running dbt tests regularly enables proactive address of issues, avoidance of downtime, and ensures accurate and reliable data-driven decision-making.