Daily Test Coverage Improver - Docker Provider Test Coverage

[botantler]

Problem

The Docker provider (pkg/svc/provider/docker/) had zero test coverage despite being a critical component for local Kubernetes cluster management. According to the test coverage improvement plan (discussion #1826), pkg/svc/provider/ was identified as a high-priority area.

Solution

Created comprehensive unit tests for pkg/svc/provider/docker/provider.go with 765 lines of test code covering:

• All three label schemes (Kind, K3d, Talos)
• All Provider interface methods
• Error paths and edge cases
• Timeout handling
• 30+ test cases

Changes

Created: pkg/svc/provider/docker/provider_test.go

Coverage Impact:

File	Lines	Functions	Before	After (Est.)
pkg/svc/provider/docker/provider.go	371	18	0%	~95%+

Test Details

Functions Covered:

1. ✅ NewProvider - constructor variations
2. ✅ IsAvailable - availability checks
3. ✅ ListNodes - all label schemes + errors
4. ✅ ListAllClusters - discovery + empty scenarios
5. ✅ NodesExist - existence + error handling
6. ✅ StartNodes - start ops + timeouts/failures
7. ✅ StopNodes - stop ops + error paths
8. ✅ DeleteNodes - deletion + force remove
9. ✅ Role extraction - all node types
10. ✅ Cluster name extraction - naming patterns
11. ✅ Timeout handling - context cancellation
12. ✅ Constants validation - labels, timeouts

Testing Approach:

• Mock-based isolation (no Docker required)
• Table-driven tests for scenarios
• Parallel execution (t.Parallel())
• Helper functions per label scheme
• Error path coverage

Applying Changes

Since the workflow runs in merge queue context without push permissions, the changes are available as a patch:

Branch: test/docker-provider-coverage
Commit: 7bd3e4b

To apply manually:

git fetch origin test/docker-provider-coverage
git checkout -b test/docker-provider-coverage origin/test/docker-provider-coverage

Or use the patch file attached to this issue.

Validation

Run tests:

go test ./pkg/svc/provider/docker/... -v
go test ./pkg/svc/provider/docker/... -race -cover

Expected:

• 30+ tests pass
• No race conditions
• ~95%+ coverage for provider.go
• Execution time < 1s (mocked)

Generate coverage:

go test -coverprofile=coverage.out ./pkg/svc/provider/docker/...
go tool cover -func=coverage.out
go tool cover -html=coverage.out -o coverage-docker.html

Impact

This PR directly addresses the coverage improvement plan priorities and adds substantial test coverage to a previously untested critical component.

Next Steps:

• Similar test coverage for pkg/svc/provider/hetzner/ (currently 0%)
• Additional provider edge cases
• Integration tests (optional, for system test suite)

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Related: Daily Test Coverage Improver workflow, discussion #1826

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