test(hypervisors/firecracker): Add unit test suite for Firecracker config generation

[safiya2610]

Problem

The Firecracker hypervisor implementation in pkg/unikontainers/hypervisors/firecracker.go currently lacks unit test coverage. Since Firecracker dynamically generates a JSON configuration file (config.json) containing settings for boot-source, machine-config, network-interfaces, and drives, a comprehensive unit test suite is needed to ensure these configurations and the resulting CLI arguments are correctly generated without regressions.

Summary

This PR introduces a comprehensive table-driven unit test suite (firecracker_test.go) for the Firecracker driver.

Changes include:

• TestFirecrackerBuildExecCmd: Verifies ExecCommand() by parsing the JSON file generated in /tmp/ and ensuring proper translation of:
  • vcpu and memory parameters into the machine-config.
  • MonitorNetArgs into network-interfaces (including mac and host_dev_name).
  • MonitorBlockArgs into drives (including correct is_root_device and is_read_only states).
  • Proper generation of the CLI command with --no-api and --config-file.
• TestFirecrackerProperties: Verifies that Firecracker properly returns capabilities like UsesKVM() and ignores unsupported SharedFS parameters.

Testing

• Tested locally via go test -v ./pkg/unikontainers/hypervisors/...
• Validated that go build does not break.

Linked Issues

Fixes: #948

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