Auto-start Cosmos emulator via Testcontainers by Copilot · Pull Request #37999 · dotnet/efcore

Copilot · 2026-03-25T19:07:37Z

Follow up to #37110

Replace explicit Docker scripts for the Cosmos emulator with automatic Testcontainers.CosmosDb lifecycle management, matching the pattern from #37809 for SQL Server. Also auto-detect the Linux emulator instead of requiring Test__Cosmos__EmulatorType=linux.

TestEnvironment connection initialization

3-path logic in TestEnvironment.InitializeAsync() (called once at assembly start via an xunit assembly fixture):

Configured endpoint — Test__Cosmos__DefaultConnection env var or config file → use directly
Localhost probe — probe https://localhost:8081 for an already-running emulator (e.g. Windows emulator or manually-started Docker container) → use if reachable
Testcontainer — start CosmosDbContainer with vnext-preview image; dispose at assembly end via the fixture

The localhost probe enables a convenient developer workflow on Windows where the emulator can be running without needing to set an environment variable. When the testcontainer fails to start, the exception is wrapped with a helpful message explaining that either the Cosmos DB emulator should be running on localhost:8081, Docker must be installed and running, or the Test__Cosmos__DefaultConnection environment variable should be set to connect to an existing emulator or Cosmos DB instance.

DefaultConnection has a sensible default initial value (from config or https://localhost:8081) so it can be read safely from constructors before initialization. InitializeAsync() is called explicitly from CosmosTestStore.InitializeAsync() rather than implicitly from property getters, to avoid accidentally starting an emulator from unit tests. After initialization, CosmosTestStore updates its ConnectionUri and ConnectionString to reflect any changes (e.g., testcontainer startup).

Assembly fixture for container lifecycle

The testcontainer lifecycle is managed via an xunit assembly fixture (CosmosEmulatorFixture) using a custom CosmosTestFramework → CosmosTestFrameworkExecutor → CosmosTestAssemblyRunner chain:

CosmosEmulatorFixture.InitializeAsync() calls TestEnvironment.InitializeAsync() once at assembly start, before any test classes are constructed
CosmosEmulatorFixture.DisposeAsync() calls TestEnvironment.DisposeAsync() at assembly end, which stops and disposes the testcontainer if one was started
This replaces the previous ProcessExit event handler approach, ensuring proper cleanup through xunit's lifecycle

Linux emulator auto-detection

IsLinuxEmulator is now true when:

Testcontainer is running (always Linux image), or
OS is not Windows (existing heuristic), or
EmulatorType config explicitly set to "linux" (backward compat)

No env var required to opt into the Linux emulator — it is detected automatically.

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

- Add Testcontainers.CosmosDb package reference - Rewrite TestEnvironment.cs with lazy connection init that auto-starts a testcontainer when no emulator is configured or reachable - Use testcontainer's HttpMessageHandler for URI rewriting - Auto-detect Linux emulator (always true for testcontainers) - Set cosmosConfig.json DefaultConnection to null for auto-detection - Simplify helix.proj (remove manual Docker pre/post commands) - Remove EmulatorType env var from copilot-setup-steps.yml - Update SKILL.md with new testcontainer approach Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/655b1ac0-f385-43cf-9276-b3c6b2501432

Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/655b1ac0-f385-43cf-9276-b3c6b2501432

AndriySvyryd

@copilot Remove the run-cosmos-container scripts

…re helix/copilot env vars, delete scripts - Make TestEnvironment initialization fully async (InitializeAsync) - Set DefaultConnection and HttpMessageHandler values during async init - If SkipConnectionCheck=true, let testcontainer failures throw - Create HttpClient instance outside the lambda in ApplyConfiguration - Inline IsTestContainer (removed property) - Restore copilot-setup-steps.yml env vars (EmulatorType, DefaultConnection, SkipConnectionCheck) - Restore helix.proj Windows.11 block and SkipConnectionCheck for Ubuntu - Delete eng/testing/run-cosmos-container.{sh,ps1} - Update SKILL.md Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/7f2ba766-d1b7-484b-899c-4b6d320a97e5

Copilot · 2026-03-25T19:45:12Z

@copilot Remove the run-cosmos-container scripts

Done in 6df36b8. Deleted both eng/testing/run-cosmos-container.sh and eng/testing/run-cosmos-container.ps1.

Copilot

Pull request overview

This PR updates EF Core Cosmos functional test infrastructure to automatically provision the Azure Cosmos DB emulator via Testcontainers.CosmosDb, replacing explicit Docker scripts and simplifying Linux emulator detection for CI and local runs.

Changes:

Add async Cosmos connection initialization with a configured-endpoint → localhost probe → testcontainer fallback sequence.
Switch Cosmos test HTTP handling to optionally use the testcontainer-provided HttpMessageHandler.
Remove Helix/Docker Cosmos emulator scripts and update CI/setup configuration and internal skill docs accordingly.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/EFCore.Cosmos.FunctionalTests/cosmosConfig.json	Sets `DefaultConnection` to `null` to enable auto-detection rather than forcing localhost.
test/EFCore.Cosmos.FunctionalTests/TestUtilities/TestEnvironment.cs	Implements async initialization, testcontainer startup, and Linux emulator auto-detection.
test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosTestStore.cs	Ensures `TestEnvironment.InitializeAsync()` runs before connection availability checks.
test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosDbContextOptionsBuilderExtensions.cs	Uses testcontainer handler when available; adjusts HttpClient creation/factory usage.
test/EFCore.Cosmos.FunctionalTests/EFCore.Cosmos.FunctionalTests.csproj	Adds `Testcontainers.CosmosDb` dependency for Cosmos functional tests.
test/Directory.Packages.props	Adds centralized package version for `Testcontainers.CosmosDb`.
eng/testing/run-cosmos-container.sh	Removes Linux Docker script (superseded by testcontainers).
eng/testing/run-cosmos-container.ps1	Removes Windows Docker script (superseded by testcontainers).
eng/helix.proj	Removes Ubuntu Cosmos Docker pre/post commands; relies on testcontainer auto-start.
.github/workflows/copilot-setup-steps.yml	Pins Cosmos env vars to use the workflow’s service container and avoid starting a second emulator.
.agents/skills/cosmos-provider/SKILL.md	Updates Cosmos test/emulator documentation to match the new testcontainer-based flow.

…:false, add DefaultConnection initial value Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/2469bf2b-2857-4f34-89ee-e1c963e35d9d

…ILL.md suggestion Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/655b5153-de78-4ee4-988b-30f981564c60

…remove localhost probing and failure fallback Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/ab54e2d2-c2e8-4385-8da4-f514a5ab5f11 Co-authored-by: roji <1862641+roji@users.noreply.github.com>

Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/dfeb7657-0a60-4352-99d3-2c2a83f58c14 Co-authored-by: roji <1862641+roji@users.noreply.github.com>

roji · 2026-03-28T07:50:26Z

+
+            _container = container;
+
+            AppDomain.CurrentDomain.ProcessExit += (_, _) =>


We'd ideally use an xunit assembly fixture to start and stop the container.

@copilot use an xunit assembly fixture to start and stop the container.

Done in 8ea3913. Implemented a custom xunit test framework (CosmosTestFramework → CosmosTestFrameworkExecutor → CosmosTestAssemblyRunner) that manages a CosmosEmulatorFixture as an assembly-wide fixture. The fixture calls TestEnvironment.InitializeAsync() before any tests run and TestEnvironment.DisposeAsync() after all tests complete. Removed the ProcessExit handler from TestEnvironment.

The Xunit.Extensions.AssemblyFixture NuGet package wasn't available in the configured feeds, so I implemented a minimal version inline using XunitTestFramework/XunitTestAssemblyRunner hooks.

Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/a26908c4-620d-4aab-becc-397ea330aed7 Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>

Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/adbe06d2-7d81-443d-b5fc-9d87f693de49 Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>

AndriySvyryd · 2026-04-01T01:14:27Z

@copilot Revert changes from 8ea3913 and 3a44583

Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/cf8f0f07-50d1-47f8-b14b-4aa7f4231898 Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>

Copilot · 2026-04-01T01:19:31Z

@copilot Revert changes from 8ea3913 and 3a44583effd3f8d8c39391...

Done in 91b538a. Reverted the xunit assembly fixture changes from 8ea3913 and 3a44583 — deleted CosmosEmulatorFixture.cs and CosmosTestFramework.cs, restored TestAssemblyCondition.cs and TestEnvironment.cs to their pre-assembly-fixture state (with ProcessExit handler for container disposal).

Copilot AI and others added 2 commits March 25, 2026 02:31

Address code review feedback: add clarifying comments to catch blocks

09480a5

Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/655b1ac0-f385-43cf-9276-b3c6b2501432

Copilot AI assigned Copilot and AndriySvyryd Mar 25, 2026

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Comment thread .agents/skills/cosmos-provider/SKILL.md Outdated

Comment thread .github/workflows/copilot-setup-steps.yml

Copilot started work on behalf of AndriySvyryd March 25, 2026 20:24 View session

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Copilot started work on behalf of AndriySvyryd March 25, 2026 20:37 View session

Make DefaultConnection throw if read before InitializeAsync, apply SK…

0fa9387

…ILL.md suggestion Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/655b5153-de78-4ee4-988b-30f981564c60

AndriySvyryd marked this pull request as ready for review March 25, 2026 20:45

AndriySvyryd requested a review from a team as a code owner March 25, 2026 20:45

Copilot AI review requested due to automatic review settings March 25, 2026 20:45

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AndriySvyryd assigned roji and unassigned AndriySvyryd and Copilot Mar 25, 2026

Copilot started work on behalf of roji March 27, 2026 08:27 View session

roji assigned AndriySvyryd and unassigned roji Mar 27, 2026

Simplify InitializeAsync: just configured endpoint or testcontainer, …

d2b56b1

…remove localhost probing and failure fallback Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/ab54e2d2-c2e8-4385-8da4-f514a5ab5f11 Co-authored-by: roji <1862641+roji@users.noreply.github.com>

Copilot finished work on behalf of roji March 27, 2026 08:38

Copilot AI requested a review from roji March 27, 2026 08:38

AndriySvyryd assigned roji and unassigned AndriySvyryd Mar 27, 2026

Copilot started work on behalf of roji March 28, 2026 07:39 View session

Add helpful error message when Cosmos testcontainer startup fails

b0ae4a8

Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/dfeb7657-0a60-4352-99d3-2c2a83f58c14 Co-authored-by: roji <1862641+roji@users.noreply.github.com>

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Copilot started work on behalf of AndriySvyryd March 28, 2026 18:45 View session

Restore localhost probing before testcontainer fallback

2aa85dd

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Copilot finished work on behalf of AndriySvyryd March 28, 2026 18:54

Copilot started work on behalf of AndriySvyryd April 1, 2026 00:27 View session

Copilot AI and others added 2 commits April 1, 2026 00:52

Use xunit assembly fixture for Cosmos emulator container lifecycle

8ea3913

Agent-Logs-Url: https://github.com/dotnet/efcore/sessions/adbe06d2-7d81-443d-b5fc-9d87f693de49 Co-authored-by: AndriySvyryd <6539701+AndriySvyryd@users.noreply.github.com>

Store initialization exception in CosmosEmulatorFixture for diagnostics

3a44583

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Copilot finished work on behalf of AndriySvyryd April 1, 2026 00:59

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Revert xunit assembly fixture changes from 8ea3913 and 3a44583

91b538a

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Copilot finished work on behalf of AndriySvyryd April 1, 2026 01:20

AndriySvyryd merged commit 23054e8 into main Apr 1, 2026
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AndriySvyryd deleted the copilot/automate-cosmos-emulator-startup branch April 1, 2026 16:36

dotnet-maestro Bot mentioned this pull request Apr 2, 2026

[main] Source code updates from dotnet/efcore dotnet/dotnet#5847

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roji linked an issue Apr 20, 2026 that may be closed by this pull request

Use testcontainer for testing Cosmos DB #33189

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roji mentioned this pull request Apr 20, 2026

Use testcontainer for testing Cosmos DB #33189

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		_container = container;

		AppDomain.CurrentDomain.ProcessExit += (_, _) =>

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TestEnvironment connection initialization

Assembly fixture for container lifecycle

Linux emulator auto-detection

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Pull request overview

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Copilot AI commented Mar 25, 2026 •

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