Software engineering best practices for notebooks

This article provides a hands-on walkthrough that demonstrates how to apply software engineering best practices to your Databricks notebooks, including version control, code sharing, testing, and optionally continuous integration and continuous delivery or deployment (CI/CD).

In this walkthrough, you will:

• Add notebooks to Databricks Git folders for version control.

• Extract portions of code from one of the notebooks into a shareable module.

• Test the shared code.

• Run the notebooks from a Databricks job.

• Optionally apply CI/CD to the shared code.

Requirements

To complete this walkthrough, you must provide the following resources:

• A remote repository with a Git provider that Databricks supports. This article’s walkthrough uses GitHub. This walkthrough assumes that you have a GitHub repository named best-notebooks available. (You can give your repository a different name. If you do, replace best-notebooks with your repo’s name throughout this walkthrough.) Create a GitHub repo if you do not already have one.

  Note

  If you create a new repo, be sure to initialize the repository with at least one file, for example a README file.

• A Databricks workspace. Create a workspace if you do not already have one.

• A Databricks all-purpose cluster in the workspace. To run notebooks during the design phase, you attach the notebooks to a running all-purpose cluster. Later on, this walkthrough uses a Databricks job to automate running the notebooks on this cluster. (You can also run jobs on job clusters that exist only for the jobs’ lifetimes.) Create an all-purpose cluster if you do not already have one.

Step 1: Set up Databricks Git folders

In this step, you connect your existing GitHub repo to Databricks Git folders in your existing Databricks workspace.

To enable your workspace to connect to your GitHub repo, you must first provide your workspace with your GitHub credentials, if you have not done so already.

Step 1.1: Provide your GitHub credentials

1. Click your username at the top right of the workspace, and then click Settings in the dropdown list.

2. In the Settings sidebar, under User, click Linked accounts.

3. Under Git integration, for Git provider, select GitHub.

4. Click Personal access token.

5. For Git provider username or email, enter your GitHub username.

6. For Token, enter your GitHub personal access token (classic). This personal access token (classic) must have the repo and workflow permissions.

7. Click Save.

Step 1.2: Connect to your GitHub repo

1. On the workspace sidebar, click Workspace.

2. In the Workspace browser, expand Workspace > Users.

3. Right-click your username folder, and then click Create > Git folder.

4. In the Create Git folder dialog:

   1. For Git repository URL, enter the GitHub Clone with HTTPS URL for your GitHub repo. This article assumes that your URL ends with best-notebooks.git, for example https://github.com/<your-GitHub-username>/best-notebooks.git.

   2. For Git provider, select GitHub.

   3. Leave Git folder name set to the name of your repo, for example best-notebooks.

   4. Click Create Git folder.

Step 2: Import and run the notebook

In this step, you import an existing external notebook into your repo. You could create your own notebooks for this walkthrough, but to speed things up we provide them for you here.

Step 2.1: Create a working branch in the repo

In this substep, you create a branch named eda in your repo. This branch enables you to work on files and code independently from your repo’s main branch, which is a software engineering best practice. (You can give your branch a different name.)

Note

In some repos, the main branch may be named master instead. If so, replace main with master throughout this walkthrough.

Tip

If you’re not familiar with working in Git branches, see Git Branches - Branches in a Nutshell on the Git website.

1. The Git folder from Step 1.2 should be open. If not, then in the Workspace sidebar, expand Workspace > Users, then expand your username folder, and click your Git folder.

2. Next to the folder name under the workspace navigation breadcrumb, click the main Git branch button.

3. In the best-notebooks dialog, click the Create branch button.

   Note

   If your repo has a name other than best-notebooks, this dialog’s title will be different, here and throughout this walkthrough.

4. Enter eda, and click Create.

5. Close this dialog.

Step 2.2: Import the notebook into the repo

In this substep, you import an existing notebook from another repo into your repo. This notebook does the following:

• Copies a CSV file from the owid/covid-19-data GitHub repository onto a cluster in your workspace. This CSV file contains public data about COVID-19 hospitalizations and intensive care metrics from around the world.

• Reads the CSV file’s contents into a pandas DataFrame.

• Filters the data to contain metrics from only the United States.

• Displays a plot of the data.

• Saves the pandas DataFrame as a Pandas API on Spark DataFrame.

• Performs data cleansing on the Pandas API on Spark DataFrame.

• Writes the Pandas API on Spark DataFrame as a Delta table in your workspace.

• Displays the Delta table’s contents.

While you could create your own notebook in your repo here, importing an existing notebook instead helps to speed up this walkthrough. To create a notebook in this branch or move an existing notebook into this branch instead of importing a notebook, see Workspace files basic usage.

1. From the best-notebooks Git folder, click Create > Folder.

2. In the New folder dialog, enter notebooks, and then click Create.

3. From the notebooks folder, click the kebab, then Import.

4. In the Import dialog:

   1. For Import from, select URL.

   2. Enter the URL to the raw contents of the covid_eda_raw notebook in the databricks/notebook-best-practices repo in GitHub. To get this URL:

      1. Go to https://github.com/databricks/notebook-best-practices.

      2. Click the notebooks folder.

      3. Click the covid_eda_raw.py file.

      4. Click Raw.

      5. Copy the full URL from your web browser’s address bar over into the Import dialog.

         Note

         The Import dialog works with Git URLs for public repositories only.

   3. Click Import.

Step 2.3: Run the notebook

1. If the notebook is not already showing, open the notebooks folder, and then click the covid_eda_raw notebook inside of the folder.

2. Select the cluster to attach this notebook to. For instructions on creating a cluster, see Create a cluster.

3. Click Run All.

4. Wait while the notebook runs.

After the notebook finishes running, in the notebook you should see a plot of the data as well as over 600 rows of raw data in the Delta table. If the cluster was not already running when you started running this notebook, it could take several minutes for the cluster to start up before displaying the results.

Step 2.4: Check in and merge the notebook

In this substep, you save your work so far to your GitHub repo. You then merge the notebook from your working branch into your repo’s main branch.

1. Next to the notebook’s name, click the eda Git branch button.

2. In the best-notebooks dialog, on the Changes tab, make sure the notebooks/covid_eda_raw.py file is selected.

3. For Commit message (required), enter Added raw notebook.

4. For Description (optional), enter This is the first version of the notebook.

5. Click Commit & Push.

6. Click the pull request link in Create a pull request on your git provider in the banner.

7. In GitHub, create the pull request, and then merge the pull request into the main branch.

8. Back in your Databricks workspace, close the best-notebooks dialog if it is still showing.

Step 3: Move code into a shared module

In this step, you move some of the code in your notebook into a set of shared functions outside of your notebook. This enables you to use these functions with other similar notebooks, which can speed up future coding and help ensure more predictable and consistent notebook results. Sharing this code also enables you to more easily test these functions, which as a software engineering best practice can raise the overall quality of your code as you go.

Step 3.1: Create another working branch in the repo

1. Next to the notebook’s name, click the eda Git branch button.

2. In the best-notebooks dialog, click the drop-down arrow next to the eda branch, and select main.

3. Click the Pull button. If prompted to proceed with pulling, click Confirm.

4. Click the Create Branch button.

5. Enter first_modules, and then click Create. (You can give your branch a different name.)

6. Close this dialog.

Step 3.2: Import the notebook into the repo

To speed up this walkthrough, in this substep you import another existing notebook into your repo. This notebook does the same things as the previous notebook, except this notebook will call shared code functions that are stored outside of the notebook. Again, you could create your own notebook in your repo here and do the actual code sharing yourself.

1. From the Workspace browser, right-click the notebooks folder, and then click Import.

2. In the Import dialog:

   1. For Import from, select URL.

   2. Enter the URL to the raw contents of the covid_eda_modular notebook in the databricks/notebook-best-practices repo in GitHub. To get this URL:

      1. Go to https://github.com/databricks/notebook-best-practices.

      2. Click the notebooks folder.

      3. Click the covid_eda_modular.py file.

      4. Click Raw.

      5. Copy the full URL from your web browser’s address bar over into the Import Notebooks dialog.

         Note

         The Import Notebooks dialog works with Git URLs for public repositories only.

   3. Click Import.

Step 3.3: Add the notebook’s supporting shared code functions

1. From the Workspace browser, right-click the best-notebooks Git folder, and then click Create > Folder.

2. In the New folder dialog, enter covid_analysis, and then click Create.

3. From the covid_analysis folder click Create > File.

4. In the New File Name dialog, enter transforms.py, and then click Create File.

5. In the transforms.py editor window, enter the following code:

   import pandas as pd
   
   # Filter by country code.
   def filter_country(pdf, country="USA"):
     pdf = pdf[pdf.iso_code == country]
     return pdf
   
   # Pivot by indicator, and fill missing values.
   def pivot_and_clean(pdf, fillna):
     pdf["value"] = pd.to_numeric(pdf["value"])
     pdf = pdf.fillna(fillna).pivot_table(
       values="value", columns="indicator", index="date"
     )
     return pdf
   
   # Create column names that are compatible with Delta tables.
   def clean_spark_cols(pdf):
     pdf.columns = pdf.columns.str.replace(" ", "_")
     return pdf
   
   # Convert index to column (works with pandas API on Spark, too).
   def index_to_col(df, colname):
     df[colname] = df.index
     return df
   

Tip

For other code sharing techniques, see Share code between Databricks notebooks.

Step 3.4: Add the shared code’s dependencies

The preceding code has several Python package dependencies to enable the code to run properly. In this substep, you declare these package dependencies. Declaring dependencies improves reproducibility by using precisely defined versions of libraries.

1. From the Workspace browser, right-click the best-notebooks Git folder, and then click Create > File.

   Note

   You want the file that lists package dependencies to go into the Git folder’s root, not into the notebooks or covid_analysis folders.

2. In the New File Name dialog, enter requirements.txt, and then click Create File.

3. In the requirements.txt editor window, enter the following code:

   Note

   If the requirements.txt file is not visible, you may need to refresh your web browser.

   -i https://pypi.org/simple
   attrs==21.4.0
   cycler==0.11.0
   fonttools==4.33.3
   iniconfig==1.1.1
   kiwisolver==1.4.2
   matplotlib==3.5.1
   numpy==1.22.3
   packaging==21.3
   pandas==1.4.2
   pillow==9.1.0
   pluggy==1.0.0
   py==1.11.0
   py4j==0.10.9.3
   pyarrow==7.0.0
   pyparsing==3.0.8
   pyspark==3.2.1
   pytest==7.1.2
   python-dateutil==2.8.2
   pytz==2022.1
   six==1.16.0
   tomli==2.0.1
   wget==3.2
   

   Note

   The preceding file lists specific package versions. For better compatibility, you can cross-reference these versions with the ones that are installed on your all-purpose cluster. See the “System environment” section for your cluster’s Databricks Runtime version in Databricks Runtime release notes versions and compatibility.

Your repo structure should now look like this:

|-- covid_analysis
│  └── transforms.py
├── notebooks
│  ├── covid_eda_modular
│  └── covid_eda_raw (optional)
└── requirements.txt

Step 3.5: Run the refactored notebook

In this substep, you run the covid_eda_modular notebook, which calls the shared code in covid_analysis/transforms.py.

1. From the Workspace browser, click the covid_eda_modular notebook inside the notebooks folder.

2. Select the cluster to attach this notebook to.

3. Click Run All.

4. Wait while the notebook runs.

After the notebook finishes running, in the notebook you should see similar results as the covid_eda_raw notebook: a plot of the data as well as over 600 rows of raw data in the Delta table. The main difference with this notebook is that a different filter is used (an iso_code of DZA instead of USA). If the cluster was not already running when you started running this notebook, it could take several minutes for the cluster to start up before displaying the results.

Step 3.6: Check in the notebook and its related code

1. Next to the notebook’s name, click the first_modules Git branch button.

2. In the best-notebooks dialog, on the Changes tab, make sure the following are selected:

   • requirements.txt

   • covid_analysis/transforms.py

   • notebooks/covid_eda_modular.py

3. For Commit message (required), enter Added refactored notebook.

4. For Description (optional), enter This is the second version of the notebook.

5. Click Commit & Push.

6. Click the pull request link in Create a pull request on your git provider in the banner.

7. In GitHub, create the pull request, and then merge the pull request into the main branch.

8. Back in your Databricks workspace, close the best-notebooks dialog if it is still showing.

Step 4: Test the shared code

In this step, you test the shared code from the last step. However, you want to test this code without running the covid_eda_modular notebook itself. This is because if the shared code fails to run, the notebook itself would likely fail to run as well. You want to catch failures in your shared code first before having your main notebook eventually fail later. This testing technique is a software engineering best practice.

Tip

For additional approaches to testing for notebooks, as well as testing for R and Scala notebooks, see Unit testing for notebooks.

Step 4.1: Create another working branch in the repo

1. Next to the notebook’s name, click the first_modules Git branch button.

2. In the best-notebooks dialog, click the drop-down arrow next to the first_modules branch, and select main.

3. Click the Pull button. If prompted to proceed with pulling, click Confirm.

4. Click Create Branch.

5. Enter first_tests, and then click Create. (You can give your branch a different name.)

6. Close this dialog.

Step 4.2: Add the tests

In this substep, you use the pytest framework to test your shared code. In these tests, you assert whether particular test results are achieved. If any test produces an unexpected result, that particular test fails the assertion and thus the test itself fails.

1. From the Workspace browser, right-click your Git folder, and then click Create > Folder.

2. In the New folder dialog, enter tests, and then click Create.

3. From the tests folder, click Create > File.

4. In the New File Name dialog, enter testdata.csv, and then click Create File.

5. In testdata.csv editor window, enter the following test data:

   entity,iso_code,date,indicator,value
   United States,USA,2022-04-17,Daily ICU occupancy,
   United States,USA,2022-04-17,Daily ICU occupancy per million,4.1
   United States,USA,2022-04-17,Daily hospital occupancy,10000
   United States,USA,2022-04-17,Daily hospital occupancy per million,30.3
   United States,USA,2022-04-17,Weekly new hospital admissions,11000
   United States,USA,2022-04-17,Weekly new hospital admissions per million,32.8
   Algeria,DZA,2022-04-18,Daily ICU occupancy,1010
   Algeria,DZA,2022-04-18,Daily ICU occupancy per million,4.5
   Algeria,DZA,2022-04-18,Daily hospital occupancy,11000
   Algeria,DZA,2022-04-18,Daily hospital occupancy per million,30.9
   Algeria,DZA,2022-04-18,Weekly new hospital admissions,10000
   Algeria,DZA,2022-04-18,Weekly new hospital admissions per million,32.1
   

6. From the tests folder, click Create > File.

7. In the New File Name dialog, enter transforms_test.py, and then click Create File.

8. In transforms_test.py editor window, enter the following test code. These tests use standard pytest fixtures as well as a mocked in-memory pandas DataFrame:

   # Test each of the transform functions.
   import pytest
   from textwrap import fill
   import os
   import pandas as pd
   import numpy as np
   from covid_analysis.transforms import *
   from pyspark.sql import SparkSession
   
   @pytest.fixture
   def raw_input_df() -> pd.DataFrame:
     """
     Create a basic version of the input dataset for testing, including NaNs.
     """
     return pd.read_csv('tests/testdata.csv')
   
   @pytest.fixture
   def colnames_df() -> pd.DataFrame:
     df = pd.DataFrame(
       data=[[0,1,2,3,4,5]],
       columns=[
         "Daily ICU occupancy",
         "Daily ICU occupancy per million",
         "Daily hospital occupancy",
         "Daily hospital occupancy per million",
         "Weekly new hospital admissions",
         "Weekly new hospital admissions per million"
       ]
     )
     return df
   
   # Make sure the filter works as expected.
   def test_filter(raw_input_df):
     filtered = filter_country(raw_input_df)
     assert filtered.iso_code.drop_duplicates()[0] == "USA"
   
   # The test data has NaNs for Daily ICU occupancy; this should get filled to 0.
   def test_pivot(raw_input_df):
     pivoted = pivot_and_clean(raw_input_df, 0)
     assert pivoted["Daily ICU occupancy"][0] == 0
   
   # Test column cleaning.
   def test_clean_cols(colnames_df):
     cleaned = clean_spark_cols(colnames_df)
     cols_w_spaces = cleaned.filter(regex=(" "))
     assert cols_w_spaces.empty == True
   
   # Test column creation from index.
   def test_index_to_col(raw_input_df):
     raw_input_df["col_from_index"] = raw_input_df.index
     assert (raw_input_df.index == raw_input_df.col_from_index).all()
   

Your repo structure should now look like this:

├── covid_analysis
│  └── transforms.py
├── notebooks
│  ├── covid_eda_modular
│  └── covid_eda_raw (optional)
├── requirements.txt
└── tests
    ├── testdata.csv
    └── transforms_test.py

Step 4.3: Run the tests

To speed up this walkthrough, in this substep you use an imported notebook to run the preceding tests. This notebook downloads and installs the tests’ dependent Python packages into your workspace, runs the tests, and reports the tests’ results. While you could run pytest from your cluster’s web terminal, running pytest from a notebook can be more convenient.

Note

Running pytest runs all files whose names follow the form test_*.py or /*_test.py in the current directory and its subdirectories.

1. From the Workspace browser, right-click the notebooks folder, and then click Import.

2. In the Import Notebooks dialog:

   1. For Import from, select URL.

   2. Enter the URL to the raw contents of the run_unit_tests notebook in the databricks/notebook-best-practices repo in GitHub. To get this URL:

      1. Go to https://github.com/databricks/notebook-best-practices.

      2. Click the notebooks folder.

      3. Click the run_unit_tests.py file.

      4. Click Raw.

      5. Copy the full URL from your web browser’s address bar over into the Import Notebooks dialog.

         Note

         The Import Notebooks dialog works with Git URLs for public repositories only.

   3. Click Import.

3. Select the cluster to attach this notebook to.

4. Click Run All.

5. Wait while the notebook runs.

After the notebook finishes running, in the notebook you should see information about the number of passing and failed tests, along with other related details. If the cluster was not already running when you started running this notebook, it could take several minutes for the cluster to start up before displaying the results.

Your repo structure should now look like this:

├── covid_analysis
│  └── transforms.py
├── notebooks
│  ├── covid_eda_modular
│  ├── covid_eda_raw (optional)
│  └── run_unit_tests
├── requirements.txt
└── tests
    ├── testdata.csv
    └── transforms_test.py

Step 4.4: Check in the notebook and related tests

1. Next to the notebook’s name, click the first_tests Git branch button.

2. In the best-notebooks dialog, on the Changes tab, make sure the following are selected:

   • tests/transforms_test.py

   • notebooks/run_unit_tests.py

   • tests/testdata.csv

3. For Commit message (required), enter Added tests.

4. For Description (optional), enter These are the unit tests for the shared code..

5. Click Commit & Push.

6. Click the pull request link in Create a pull request on your git provider in the banner.

7. In GitHub, create the pull request, and then merge the pull request into the main branch.

8. Back in your Databricks workspace, close the best-notebooks dialog if it is still showing.

Step 5: Create a job to run the notebooks

In previous steps, you tested your shared code manually and ran your notebooks manually. In this step, you use a Databricks job to test your shared code and run your notebooks automatically, either on-demand or on a regular schedule.

Step 5.1: Create a job task to run the testing notebook

1. On the workspace sidebar, click Workflows.

2. On the Jobs tab, click Create Job.

3. Edit the name of the job to be covid_report.

4. For Task name, enter run_notebook_tests.

5. For Type, select Notebook.

6. For Source, select Git provider.

7. Click Add a git reference.

8. In the Git information dialog:

   1. For Git repository URL, enter the GitHub Clone with HTTPS URL for your GitHub repo. This article assumes that your URL ends with best-notebooks.git, for example https://github.com/<your-GitHub-username>/best-notebooks.git.

   2. For Git provider, select GitHub.

   3. For Git reference (branch / tag / commit), enter main.

   4. Next to Git reference (branch / tag / commit), select branch.

   5. Click Confirm.

9. For Path, enter notebooks/run_unit_tests. Do not add the .py file extension.

10. For Cluster, select the cluster from the previous step.

11. Click Create task.

Note

In this scenario, Databricks does not recommend that you use the schedule button in the notebook as described in Create and manage scheduled notebook jobs to schedule a job to run this notebook periodically. This is because the schedule button creates a job by using the latest working copy of the notebook in the workspace repo. Instead, Databricks recommends that you follow the preceding instructions to create a job that uses the latest committed version of the notebook in the repo.

Step 5.2: Create a job task to run the main notebook

1. Click the + Add task icon.

2. A pop-up menu appears. Select Notebook.

3. For Task name, enter run_main_notebook.

4. For Type, select Notebook.

5. For Path, enter notebooks/covid_eda_modular. Do not add the .py file extension.

6. For Cluster, select the cluster from the previous step.

7. Verify Depends on value is run_notebook-tests.

8. Click Create task.

Step 5.3 Run the job

1. Click Run now.

2. In the pop-up, click View run.

   Note

   If the pop-up disappears too quickly, then do the following:

   1. On the sidebar in the Data Science & Engineering or Databricks Machine Learning environment, click Workflows.

   2. On the Job runs tab, click the Start time value for the latest job with covid_report in the Jobs column.

3. To see the job results, click on the run_notebook_tests tile, the run_main_notebook tile, or both. The results on each tile are the same as if you ran the notebooks yourself, one by one.

Note

This job ran on-demand. To set up this job to run on a regular basis, see Add a job schedule.

(Optional) Step 6: Set up the repo to test the code and run the notebook automatically whenever the code changes

In the previous step, you used a job to automatically test your shared code and run your notebooks at a point in time or on a recurring basis. However, you may prefer to trigger tests automatically when changes are merged into your GitHub repo, using a CI/CD tool such as GitHub Actions.

Step 6.1: Set up GitHub access to your workspace

In this substep, you set up a GitHub Actions workflow that runs jobs in the workspace whenever changes are merged into your repository. You do this by giving GitHub a unique Databricks token for access.

For security reasons, Databricks discourages you from giving your Databricks workspace user’s personal access token to GitHub. For instructions, see the GCP section of the Run Databricks Notebook GitHub Action page in the GitHub Actions Marketplace.

Important

Notebooks are run with all of the workspace permissions of the identity that is associated with the token, so Databricks recommends using a service principal. If you really want to give your Databricks workspace user’s personal access token to GitHub for personal exploration purposes only, and you understand that for security reasons Databricks discourages this practice, see the instructions to create your workspace user’s personal access token.

Step 6.2: Add the GitHub Actions workflow

In this substep, you add a GitHub Actions workflow to run the run_unit_tests notebook whenever there is a pull request to the repo.

This substep stores the GitHub Actions workflow in a file that is stored within multiple folder levels in your GitHub repo. GitHub Actions requires a specific nested folder hierarchy to exist in your repo in order to work properly. To complete this step, you must use the website for your GitHub repo, because the Databricks Git folder user interface does not support creating nested folder hierarchies.

1. In the website for your GitHub repo, click the Code tab.

2. Click the arrow next to main to expand the Switch branches or tags drop-down list.

3. In the Find or create a branch box, enter adding_github_actions.

4. Click Create branch: adding_github_actions from ‘main’.

5. Click Add file > Create new file.

6. For Name your file, enter .github/workflows/databricks_pull_request_tests.yml.

7. In the editor window, enter the following code. This code uses the pull_request hook from the Run Databricks Notebook GitHub Action to run the run_unit_tests notebook.

   In the following code, replace:

   • <your-workspace-instance-URL> with your Databricks instance name.

   • <your-access-token> with the token that you generated earlier.

   • <your-cluster-id> with your target cluster ID.

   name: Run pre-merge Databricks tests
   
   on:
     pull_request:
   
   env:
     # Replace this value with your workspace instance name.
     DATABRICKS_HOST: https://<your-workspace-instance-name>
   
   jobs:
     unit-test-notebook:
       runs-on: ubuntu-latest
       timeout-minutes: 15
   
       steps:
         - name: Checkout repo
           uses: actions/checkout@v2
         - name: Run test notebook
           uses: databricks/run-notebook@main
           with:
             databricks-token: <your-access-token>
   
             local-notebook-path: notebooks/run_unit_tests.py
   
             existing-cluster-id: <your-cluster-id>
   
             git-commit: "${{ github.event.pull_request.head.sha }}"
   
             # Grant all users view permission on the notebook's results, so that they can
             # see the result of the notebook, if they have related access permissions.
             access-control-list-json: >
               [
                 {
                   "group_name": "users",
                   "permission_level": "CAN_VIEW"
                 }
               ]
             run-name: "EDA transforms helper module unit tests"
   

8. Click Commit changes.

9. In the Commit changes dialog, enter Create databricks_pull_request_tests.yml into Commit message

10. Select Commit directly to the adding_github_actions branch and click Commit changes.

11. On the Code tab, click Compare & pull request, and then create the pull request.

12. On the pull request page, wait for the icon next to Run pre-merge Databricks tests / unit-test-notebook (pull_request) to display a green check mark. (It may take a few moments for the icon to appear.) If there is a red X instead of a green check mark, click Details to find out why. If the icon or Details are no longer showing, click Show all checks.

13. If the green check mark appears, merge the pull request into the main branch.

(Optional) Step 7: Update the shared code in GitHub to trigger tests

In this step, you make a change to the shared code and then push the change into your GitHub repo, which immediately triggers the tests automatically, based on the GitHub Action from the previous step.

Step 7.1: Create another working branch in the repo

1. From the Workspace browser, open the best-notebooks Git folder.

2. Next to the folder’s name, click the first_tests Git branch button.

3. In the best-notebooks dialog, click the drop-down arrow next to the first_tests branch, and select main.

4. Click the Pull button. If prompted to proceed with pulling, click Confirm.

5. Click the + (Create branch) button.

6. Enter trigger_tests, and then click Create. (You can give your branch a different name.)

7. Close this dialog.

Step 7.2: Change the shared code

1. From the Workspace browser, in the best-notebooks Git folder, click the covid_analysis/transforms.py file.

2. Change the third line of this file:

   # Filter by country code.
   

   To this:

   # Filter by country code. If not specified, use "USA."
   

Step 7.3: Check in the change to trigger the tests

1. Next to the file’s name, click the trigger_tests Git branch button.

2. In the best-notebooks dialog, on the Changes tab, make sure covid_analysis/transforms.py is selected.

3. For Commit message (required), enter Updated comment.

4. For Description (optional), enter This updates the comment for filter_country.

5. Click Commit & Push.

6. Click the pull request link in Create a pull request on your git provider in the banner, and then create the pull request in GitHub.

7. On the pull request page, wait for the icon next to Run pre-merge Databricks tests / unit-test-notebook (pull_request) to display a green check mark. (It may take a few moments for the icon to appear.) If there is a red X instead of a green check mark, click Details to find out why. If the icon or Details are no longer showing, click Show all checks.

8. If the green check mark appears, merge the pull request into the main branch.