refactor!: use TestContainers #458

m4tx · 2026-01-27T22:30:15Z

This changes the Cot's testing framework to use Testcontainers instead of manually spinning up Docker containers.

This change:

makes it easier to run the tests,
gives us a bit more flexibility in testing various versions of the dependencies,
makes all the tests 100% isolated from each other,
makes the tests more robust. It removes our custom Redis database allocation code - while it was smart, it wasn't perfect, and it sometimes caused the tests to be flaky.

This comes with some drawbacks, though:

higher test runtime,
more resource usage in general,
huge increase in the number of dependencies (hence the removal of test feature flag from the full feature set)

Whether it's worth it - I'm leaving this for others to decide.

github-actions · 2026-01-27T22:35:44Z

Bencher Report

Branch	test-containers
Testbed	github-ubuntu-latest

Click to view all benchmark results

Benchmark	Latency	Benchmark Result microseconds (µs) (Result Δ%)	Upper Boundary microseconds (µs) (Limit %)
empty_router/empty_router	📈 view plot 🚷 view threshold	6,730.90 µs (+13.36%) Baseline: 5,937.82 µs	7,140.99 µs (94.26%)
json_api/json_api	📈 view plot 🚷 view threshold	1,052.10 µs (+3.57%) Baseline: 1,015.79 µs	1,162.89 µs (90.47%)
nested_routers/nested_routers	📈 view plot 🚷 view threshold	972.02 µs (+3.84%) Baseline: 936.08 µs	1,065.51 µs (91.23%)
single_root_route/single_root_route	📈 view plot 🚷 view threshold	935.89 µs (+4.31%) Baseline: 897.23 µs	1,023.90 µs (91.40%)
single_root_route_burst/single_root_route_burst	📈 view plot 🚷 view threshold	17,985.00 µs (+2.35%) Baseline: 17,572.13 µs	20,842.61 µs (86.29%)

🐰 View full continuous benchmarking report in Bencher

Copilot

Pull request overview

This pull request refactors the testing framework to use Testcontainers instead of manually spinning up Docker containers. The change improves test isolation and makes it easier to run tests, but comes with increased resource usage and a significantly larger dependency footprint.

Changes:

Replaced manual Docker Compose setup with Testcontainers for all external test dependencies (PostgreSQL, MariaDB/MySQL, Redis, Selenium WebDriver)
Removed the test feature from the full feature set and made it an optional dependency
Updated CI/CD workflows to remove Docker Compose startup steps
Added comprehensive WebDriver management through TestServerWithWebDriver wrapper
Modified test ignore messages to be more accurate

Reviewed changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
justfile	Removed Docker Compose commands from test targets, simplified test execution
cot/tests/admin.rs	Updated WebDriver integration to use Testcontainers, improved test function signatures
cot/src/test.rs	Major refactoring to use Testcontainers for databases, Redis, and Selenium; added TestServerWithWebDriver and TestWebDriver types
cot/src/session/store/redis.rs	Updated Redis tests to use containerized Redis instances
cot/src/cache/store/redis.rs	Updated cache tests to use containerized Redis instances
cot/Cargo.toml	Added testcontainers dependencies, removed `test` from `full` feature
cot-cli/src/project_template/Cargo.toml.template	Added `test` feature to dev-dependencies for new projects
compose.yml	Deleted - no longer needed for testing
clippy.toml	Added "WebDriver" to valid identifiers
README.md	Updated test instructions to remove Docker Compose requirement
CONTRIBUTING.md	Updated test documentation to reflect Testcontainers usage
.github/workflows/rust.yml	Removed Docker Compose setup steps from CI/CD
Cargo.lock	Added numerous new dependencies for testcontainers ecosystem
cot-macros/tests/ui/derive_into_response_missing_trait_impl.stderr	Minor compiler output formatting change

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Copilot · 2026-02-02T00:06:26Z

cot/src/test.rs

+    /// function, you can set the `COT_TEST_SERVER_HOST` environment variable
+    /// or call [`Self::set_host`].
    ///


The documentation references a non-existent method Self::set_host. Either this method needs to be implemented or the reference should be removed from the documentation.

Suggested change

/// function, you can set the `COT_TEST_SERVER_HOST` environment variable

/// or call [`Self::set_host`].

///

/// function, you can set the `COT_TEST_SERVER_HOST` environment variable.

///

///

Copilot · 2026-02-02T00:06:26Z

cot/src/test.rs

+                    .raw(&format!(
+                        "SELECT pg_terminate_backend(pg_stat_activity.pid) \
+                         FROM pg_stat_activity \
+                         WHERE pg_stat_activity.datname = '{db_name}' \
+                         AND pid <> pg_backend_pid()"
+                    ))


SQL injection vulnerability: the database name is interpolated directly into the SQL query without proper escaping or parameterization. Although test names are typically controlled, this creates a security risk if a malicious test name is used. Consider using PostgreSQL identifier quoting (e.g., wrapping the identifier in double quotes and escaping any double quotes within it), or using a parameterized query if the database driver supports it for DDL operations.

Copilot · 2026-02-02T00:06:26Z

cot/src/test.rs

+                    ))
                    .await?;
+
+                database.raw(&format!("DROP DATABASE {db_name}")).await?;


SQL injection vulnerability: the database name is interpolated directly into the SQL query without proper escaping or parameterization. Although test names are typically controlled, this creates a security risk if a malicious test name is used. Consider using proper identifier quoting or parameterized queries.

Copilot · 2026-02-02T00:06:26Z

cot/src/test.rs

+            } => {
                let database = Database::new(format!("{db_url}/mysql")).await?;

                database.raw(&format!("DROP DATABASE {db_name}")).await?;


SQL injection vulnerability: the database name is interpolated directly into the SQL query without proper escaping or parameterization. Although test names are typically controlled, this creates a security risk if a malicious test name is used. Consider using proper identifier quoting or parameterized queries.

Copilot · 2026-02-02T00:06:27Z

CONTRIBUTING.md

+container is automatically started using Testcontainers.
+
+Alternatively, you can run the tests with a local webdriver server. To do this,
+you need to set the `WEBDRIVER_URL` environment variable to the URL of your


Environment variable name inconsistency: The documentation mentions WEBDRIVER_URL but the code uses COT_WEBDRIVER_URL. These should be consistent. Either update the documentation to say COT_WEBDRIVER_URL or change the code to use WEBDRIVER_URL.

Suggested change

you need to set the `WEBDRIVER_URL` environment variable to the URL of your

you need to set the `COT_WEBDRIVER_URL` environment variable to the URL of your

codecov · 2026-02-02T00:56:03Z

Codecov Report

❌ Patch coverage is 72.50000% with 44 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cot/src/test.rs	67.64%	29 Missing and 15 partials ⚠️

Flag	Coverage Δ
rust	`89.56% <72.50%> (-0.13%)`	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cot/src/cache/store/redis.rs	`92.67% <100.00%> (ø)`
cot/src/session/store/redis.rs	`88.23% <100.00%> (+0.08%)`	⬆️
cot/src/test.rs	`81.71% <67.64%> (-4.19%)`	⬇️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

justfile

clippy.toml

seqre · 2026-02-02T08:25:00Z

cot/src/test.rs

+            let host_port = container
+                .get_host_port_ipv4(POSTGRES_PORT)
+                .await
+                .map_err(|e| {
+                    TestcontainersError::new("failed to get PostgreSQL container port", e)
+                })?;
+            let host_port: u16 = host_port;


Why two let statements?

seqre · 2026-02-02T08:31:19Z

cot/src/test.rs

+
+#[derive(Debug, Error)]
+#[error("{message}: {inner}")]
+struct TestcontainersError {


nit: I know the name matches the library name, but it pains me it's not TestContainersError

seqre · 2026-02-02T08:33:25Z

cot/src/test.rs

+    /// # Errors
+    ///
+    /// Returns an error if the container could not be started.
+    pub async fn with_host_port_exposure(port: u16) -> Result<Self> {


Personally, I think with_host_post_exposed is better

github-actions bot added the C-lib Crate: cot (main library crate) label Jan 27, 2026

m4tx force-pushed the test-containers branch 5 times, most recently from 2478966 to 4d25196 Compare February 1, 2026 20:32

m4tx changed the title ~~refactor: use TestContainers~~ refactor!: use TestContainers Feb 1, 2026

m4tx force-pushed the test-containers branch 3 times, most recently from b3161ea to 1026eda Compare February 1, 2026 23:24

github-actions bot added the C-cli Crate: cot-cli (issues and Pull Requests related to Cot CLI) label Feb 1, 2026

m4tx force-pushed the test-containers branch from 1026eda to d535370 Compare February 1, 2026 23:26

github-actions bot added the A-ci Area: CI (Continuous Integration) label Feb 1, 2026

refactor: use TestContainers

be4bc4c

m4tx force-pushed the test-containers branch from d535370 to be4bc4c Compare February 2, 2026 00:01

m4tx marked this pull request as ready for review February 2, 2026 00:01

Copilot AI review requested due to automatic review settings February 2, 2026 00:01

github-actions bot added the C-macros Crate: cot-macros label Feb 2, 2026

m4tx requested review from ElijahAhianyo and seqre February 2, 2026 00:01

Copilot started reviewing on behalf of m4tx February 2, 2026 00:01 View session

Copilot AI reviewed Feb 2, 2026

View reviewed changes

seqre reviewed Feb 2, 2026

View reviewed changes

	you need to set the `WEBDRIVER_URL` environment variable to the URL of your
	you need to set the `COT_WEBDRIVER_URL` environment variable to the URL of your

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refactor!: use TestContainers #458

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refactor!: use TestContainers #458

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