dbt-coverage

A CLI library with Python backend for computing docs and test coverage of dbt managed data warehouses.

Installation

pip install dbt-coverage

Usage

dbt-coverage comes with two basic commands: compute and compare. The documentation for the individual commands can be shown by using the --help option.

Compute

Compute coverage from target/catalog.json and target/manifest.json files found in a dbt project, e.g. jaffle_shop. You need to select documentation or test coverage by using the respective CLI argument.

$ cd jaffle_shop
$ dbt run  # Materialize models
$ dbt docs generate  # Generate catalog.json and manifest.json
$ dbt-coverage compute doc  # Compute doc coverage, print it and write it to coverage.json file

# Coverage report
# =====================================================================
# customers                                              6/7      85.7%
# orders                                                 9/9     100.0%
# raw_customers                                          0/3       0.0%
# raw_orders                                             0/4       0.0%
# raw_payments                                           0/4       0.0%
# stg_customers                                          0/3       0.0%
# stg_orders                                             0/4       0.0%
# stg_payments                                           0/4       0.0%
# =====================================================================
# Total                                                 15/38     39.5%

$ dbt-coverage compute test  # Compute test coverage, print it and write it to coverage.json file

# Coverage report
# =====================================================================
# customers                                              1/7      14.3%
# orders                                                 8/9      88.9%
# raw_customers                                          0/3       0.0%
# raw_orders                                             0/4       0.0%
# raw_payments                                           0/4       0.0%
# stg_customers                                          1/3      33.3%
# stg_orders                                             2/4      50.0%
# stg_payments                                           2/4      50.0%
# =====================================================================
# Total                                                 14/38     36.8%

Compare

Compare two coverage.json files generated by the compute command. This is useful to ensure that the coverage does not drop while making changes to the project.

$ dbt-coverage compare coverage-after.json coverage-before.json

# Coverage delta summary
#               before     after            +/-
# =============================================
# Coverage      39.47%    38.46%         -1.01%
# =============================================
# Tables             8         8          +0/+0
# Columns           38        39          +1/+0
# =============================================
# Hits              15        15          +0/+0
# Misses            23        24          +1/+0
# =============================================

# New misses
# ==============================================================
# Catalog              15/38   (39.47%)  ->    15/39   (38.46%) 
# ==============================================================
# - customers           6/7    (85.71%)  ->     6/8    (75.00%) 
# -- new_col            -/-       (-)    ->     0/1     (0.00%) 
# ==============================================================

Combined use-case

$ cd my-dbt-project

$ dbt run  # Materialize models
$ dbt docs generate  # Generate catalog.json and manifest.json
$ dbt-coverage compute doc --cov-report before.json --cov-fail-under 0.5 # Fail if coverage is lower than 50%

# Make changes to the dbt project, e.g. add some columns to the DWH, document some columns, etc.

$ dbt docs generate
$ dbt-coverage compute doc --cov-report after.json --cov-fail-compare before.json  # Fail if the current coverage is lower than coverage in before.json
$ dbt-coverage compare after.json before.json  # Generate a detailed coverage delta report

Related packaged

https://github.com/mikaelene/dbt-test-coverage

License

Licensed under the MIT license (see LICENSE.md file for more details).