Feat/add unit tests

[Mysterio-17]

Add Unit Tests for Vaccel, Network Utils, and Rootfs Selection

Fixes: #96

This PR adds comprehensive unit tests for previously untested functions in the urunc codebase, improving overall test coverage.

Tests Added

pkg/unikontainers/vaccel_test.go (2 test functions, 15 test cases)

• TestIdToGuestCID - 4 test cases for deterministic vAccel guest CID generation from container IDs
• TestIsValidVSockAddress - 11 test cases validating vsock addresses for qemu (vsock://) and firecracker (unix://) formats

pkg/unikontainers/rootfs_test.go (3 test functions, 14 test cases)

• TestNewRootfsResult - 4 test cases for rootfs result creation (initrd, block, 9pfs, empty)
• TestRootfsSelector_TryInitrd - 3 test cases for annotation-based initrd path detection
• TestRootfsSelector_ShouldMountContainerRootfs - 7 test cases for boolean parsing (true/1/false/0/invalid/empty values)

pkg/network/network_test.go (3 test functions, 7 test cases)

• TestGetTapIndex - Tests TAP device index extraction from interface names
• TestNewNetworkManager - 5 test cases for network manager factory pattern (static/dynamic/invalid)
• TestEnsureEth0Exists - Tests eth0 interface existence validation

Summary

• Total: 8 test functions covering 36+ test cases
• Coverage: Targets previously untested utility functions in vaccel.go, rootfs.go, and network.go
• All tests passing ✅

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[cmainas]

Hello @Mysterio-17 ,

this PR also has changes from the netkit PR. These are two different PRs and the same changes should not be present in both PRs. Please remove the netkit changes from this PR and take a look in the contribution guide

[Mysterio-17]

Hello @cmainas , I’ve removed all netkit-related changes from this PR as suggested, and it now includes only unit test additions. All tests pass successfully, and the commit message has been updated to follow the contribution guidelines.
Please let me know if you have any feedback or suggestions.

[cmainas]

Hello @Mysterio-17 ,

thank you for this contribution. I have various comments:

• Please use a different method to verify the return values and errors (e.g. assert package) as we do here https://github.com/urunc-dev/urunc/blob/main/pkg/unikontainers/config_test.go. It makes the code cleaner and easier to read for a unit test
• Replace want with expect

[Mysterio-17]

Hello @cmainas,
Thanks for the thorough review! I’ve incorporated all the feedback in the latest commit.

• I refactored the tests to use github.com/stretchr/testify/assert for cleaner assertions and aligned them with the pattern in config_test.go. I also added t.Parallel() where appropriate to enable parallel execution.
• I cleaned up a few redundant cases by removing duplicate invalid network type tests (keeping a single representative one), dropping TestEnsureEth0Exists, and simplifying TestNewRootfsResult down to one focused test.
• For TestIdToGuestCID, I replaced wantMin / wantMax with constants (minCID, maxCID), removed the unused checkCID field and the determinism test, and reduced it to two clear cases that directly validate the expected return values.
• I also updated TestIsValidVSockAddress by renaming hypervisor to monitor, adding an expectedPath check for the qemu case, and renaming “unsupported hypervisor” to “unsupported monitor” for clarity.

All tests are passing now. Please let me know if any further changes are needed.