How to Unit Test Stored Procedures in SQL Server

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How do I write unit tests for stored procedures in SQL Server?

Unit testing in SQL Server validates T-SQL objects automatically, ensuring predictable behavior after code changes.

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What is unit testing in SQL Server?

Unit testing executes small, isolated pieces of T-SQL—such as functions or stored procedures—and checks the result against an expected value. The open-source tSQLt framework provides assertions, test isolation, and easy execution from SQL Server Management Studio or CI pipelines.

How do I install tSQLt quickly?

Run the framework’s installer script in the target database. It creates helper stored procedures and the tSQLt schema. Use a separate database for tests or add tests to the development copy of your app database.

Which objects should I test first?

Prioritize business-critical stored procedures—such as order creation, payment capture, and inventory updates. Unit tests catch regressions early when these procedures change.

What’s the basic workflow?

1. Create a test class to group related tests. 2. Fake or seed data into tables. 3. Execute the procedure under test. 4. Assert expected results. 5. Run all tests with one command.

How does test isolation work?

tSQLt wraps each test in a transaction and rolls it back automatically, leaving the database state unchanged and tests independent.

How to fake tables for clean tests?

Use tSQLt.FakeTable to replace real tables with empty copies. Insert only the minimal rows needed for the test, avoiding interference from production-size data.

Example: Testing `spCreateOrder`

The test fakes Orders and OrderItems, inserts a customer and products, runs spCreateOrder, then asserts that Orders.total_amount matches the sum of item prices.

How to run all tests?

Execute EXEC tSQLt.RunAll; or integrate the command in your CI pipeline. The result set shows passed and failed tests with messages.

Best practices for SQL unit tests?

Isolate data with FakeTable, keep each test focused on one behavior, use meaningful test names, and add tests to version control alongside application code.

What are performance considerations?

Because tests run in transactions and often on fake tables, they are fast and can be executed on each commit. Avoid heavy data inserts; mock only what you need.

How do I automate tests in CI/CD?

Call sqlcmd or PowerShell in the pipeline to execute tSQLt.RunAll. Fail the build when any assertion fails, enforcing code quality gates.

Why How to Unit Test Stored Procedures in SQL Server is important

How to Unit Test Stored Procedures in SQL Server Example Usage


-- Test that spUpdateStock reduces inventory correctly
EXEC tSQLt.NewTestClass 'StockTests';
GO
CREATE PROCEDURE StockTests.[test stock deducted on order]
AS
BEGIN
    -- Arrange
    EXEC tSQLt.FakeTable 'dbo', 'Products';
    INSERT INTO Products(id, name, price, stock)
    VALUES (20, 'Galaxy Mug', 12.00, 50);

    -- Act
    EXEC dbo.spUpdateStock @product_id = 20, @quantity = 3;

    -- Assert
    DECLARE @expected INT = 47;
    DECLARE @actual   INT;
    SELECT @actual = stock FROM Products WHERE id = 20;
    EXEC tSQLt.AssertEquals @expected, @actual;
END;
GO
EXEC tSQLt.Run 'StockTests';

How to Unit Test Stored Procedures in SQL Server Syntax


-- Install tSQLt (run once per database)
EXEC sp_configure 'clr enabled', 1; RECONFIGURE;
:run tsqlt.class.sql

-- 1. Create a test class
EXEC tSQLt.NewTestClass 'OrdersTests';

-- 2. Fake target tables to isolate data
EXEC tSQLt.FakeTable 'dbo', 'Orders';
EXEC tSQLt.FakeTable 'dbo', 'OrderItems';

-- 3. Seed minimal data
INSERT INTO Customers(id, name, email, created_at)
VALUES (1, 'Ada Lovelace', 'ada@shop.com', GETDATE());

INSERT INTO Products(id, name, price, stock)
VALUES (10, 'Galaxy Tee', 25.00, 100);

-- 4. Execute procedure under test
EXEC dbo.spCreateOrder @customer_id = 1,
                       @product_id = 10,
                       @qty         = 2;

-- 5. Assert expected outcome
DECLARE @expected DECIMAL(10,2) = 50.00;
DECLARE @actual   DECIMAL(10,2);
SELECT @actual = total_amount FROM Orders WHERE customer_id = 1;
EXEC tSQLt.AssertEquals @expected, @actual, 'Total does not match price × qty';

-- Run all tests
EXEC tSQLt.RunAll;

Common Mistakes

Ignoring data isolation—running tests on real tables can leave residual data, leading to flaky results. Fix by using tSQLt.FakeTable or transactions.
Asserting with hard-coded IDs that change between runs—tests fail unpredictably. Fix by seeding deterministic keys or querying generated IDs before assertions.

Frequently Asked Questions (FAQs)

Can I unit test without installing CLR?

No. tSQLt relies on CLR integration. Enable it with sp_configure 'clr enabled', 1.

Will tests affect production data?

When you use FakeTable and run tests in a non-production database, all changes roll back automatically, keeping production safe.

How many tests should I write?

Add a test for every critical path and bug fix. Over time, the suite grows with your codebase, guarding against regressions.

Want to learn about other SQL terms?

dbt tests

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

dbt utils

dbt utils is a community-maintained dbt package that adds time-saving utility macros for analytics engineers, such as generating surrogate keys, safely unioning models, and automating date spines.

dbt Tutorial Glossary: Build, Test & Deploy SQL Models

dbt is an open-source framework that lets data teams transform raw warehouse tables into tested, documented, production-ready datasets using version-controlled SQL.

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