Summary

Increase unit-test coverage for the Tracer package from the current ~10% to at least 90% line coverage.

Scope

Target package:

• src/Tracer/**

Related tests:

• tests/Unit/Tracer/**

Goals

1. Raise line coverage for src/Tracer/** to >=90%.
2. Cover core behavior and error paths, not just superficial execution.
3. Keep tests stable across local and CI environments.

Required coverage areas

• tracer initialization/configuration flows
• span/trace lifecycle behavior
• context propagation and mutation paths
• exporter/adapter integration boundaries (mocked where appropriate)
• failure/exception paths and guard clauses

Test quality requirements

• Assert observable behavior and outputs.
• Avoid coverage-only tests with no contract validation.
• Include both success and failure scenarios.
• Minimize brittle internals-based assertions.

Acceptance criteria

• Coverage report shows >=90% line coverage for src/Tracer/**.
• Tests pass locally and in CI.
• Validation passes:
  • vendor/bin/phpunit --coverage-clover coverage.xml
  • composer phpstan
  • composer cs:check

Notes

• If any file cannot reasonably hit 90%, document justification and proposed threshold in PR.