Add start & stop functions to plugin_backend #45

All 2 389 tests pass, 15 skipped in 29s

2 404 tests ±0 2 389 ✔️ ±0 29s ⏱️ -1s
      1 suites ±0     15 💤 ±0
      1 files ±0       0 ❌ ±0

Results for commit 0dc9651. ± Comparison against earlier commit 8847423.