[HofmeisterAn]

What does this PR do?

GetMappedPublicPort(string) now throws the documented InvalidOperationException when a container port is exposed but not published. Previously it threw a NullReferenceException, because Docker returns null port bindings for such ports. GetMappedPublicPorts() now groups the port bindings by container port and prefers the TCP binding when a port is mapped for more than one protocol (e.g. 53/tcp and 53/udp), consistent with GetMappedPublicPort(int). Previously ToDictionary threw an ArgumentException for the duplicate key. Because the bindings are sorted by protocol before they are grouped, GetMappedPublicPort() now returns a TCP port first when a container publishes both TCP and non-TCP ports. The IContainer.GetMappedPublicPorts() docs now describe the TCP precedence, and two new tests cover both cases.

Why is it important?

Both methods threw unexpected exceptions for valid container configurations, such as an image that exposes ports without publishing them, or a container that publishes the same port for TCP and UDP. Callers now get the TCP host port or the documented exception.

Related issues

-

Summary by CodeRabbit

• Bug Fixes

  • Port mappings now return a single entry when a container port is mapped over both TCP and UDP. The unqualified mapping uses the TCP host port, while protocol-specific lookups can still retrieve the UDP host port.
  • Looking up a port without a binding continues to report that no mapping is available, rather than returning an invalid result.

• Documentation

  • Clarified that mapped-port collections use TCP when a container port has bindings for multiple protocols, and that callers can use a protocol-qualified lookup to select another protocol.

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[coderabbitai]

Walkthrough

Mapped-port lookup now handles missing bindings and duplicate container ports across protocols. The unqualified mapping selects TCP when both TCP and UDP bindings exist. The interface remarks and tests describe these behaviors.

Changes

Mapped Port Resolution

Layer / File(s)	Summary
Resolve mapped ports src/Testcontainers/Containers/DockerContainer.cs, src/Testcontainers/Containers/IContainer.cs, tests/Testcontainers.Tests/Unit/Containers/Unix/TestcontainersContainerTest.cs	Mapped-port lookup checks for a non-empty binding list. The unqualified mapping collection selects TCP when a container port has TCP and UDP bindings. Interface remarks describe protocol selection. Tests cover TCP and UDP mappings and lookup for a port without a binding.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: 🟡 Moderate · up to 0bc29

The new TCP/UDP test can fail to start its container because it holds the host ports open while Docker tries to publish them. The library change looks sound, but the test should release the ports before the container starts so the new behavior is reliably covered.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly and concisely summarizes the two main changes: handling unpublished ports and ports mapped for multiple protocols.
Description check		The description explains what changed, why it matters, and how the behavior is tested. The optional issue reference and recommended testing steps are not provided, but the mandatory sections are compl…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks the ports at night
TCP hops into the first slot
UDP keeps its own path clear
Empty bindings raise an error
The burrow maps each port just right}

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Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at
@tests/Testcontainers.Tests/Unit/Containers/Unix/TestcontainersContainerTest.cs:
- Around line 183-189: Dispose the TCP and UDP allocation sockets after
capturing tcpHostPort and udpHostPort, but before the container’s StartAsync
call, so neither host port remains bound during startup.

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📥 Commits

Reviewing files that changed from the base of the PR and between 07ac514 and 0bc293b.

📒 Files selected for processing: 3

• src/Testcontainers/Containers/DockerContainer.cs
• src/Testcontainers/Containers/IContainer.cs
• tests/Testcontainers.Tests/Unit/Containers/Unix/TestcontainersContainerTest.cs

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