//nolint:testpackage // exercises the unexported processRate helper
package snapshot

import (
	"testing"
	"time"
)

// TestProcessRateNotLoweredByLaterScanPhase feeds the reporter two paths
// that each take 10 seconds to process, the second after a 30-second scan
// phase. That scan phase processes nothing, so the rate while the second
// path is processed must be that path's own.
func TestProcessRateNotLoweredByLaterScanPhase(t *testing.T) {
	t.Parallel()

	const (
		pathSize       = 1000
		processingTime = 10 * time.Second
		scanTime       = 30 * time.Second
	)

	// Never started, but Stop releases its tickers and signal handler.
	progress := NewProgressReporter()
	defer progress.Stop()

	stats := progress.GetStats()

	// Moves the processing start time back instead of sleeping.
	elapse := func(d time.Duration) {
		stats.mu.Lock()
		defer stats.mu.Unlock()

		stats.processStartTime = stats.processStartTime.Add(-d)
	}

	progress.AddTotalSize(pathSize)
	stats.BytesProcessed.Add(pathSize)
	elapse(processingTime)

	elapse(scanTime)
	progress.AddTotalSize(pathSize)
	stats.BytesProcessed.Add(pathSize)
	elapse(processingTime)

	want := pathSize / processingTime.Seconds()
	got := stats.processRate()

	// The test's own run time adds to the elapsed time, so got is a hair
	// under want.
	if got > want || got < want*0.99 {
		t.Errorf("rate while the second path is processed is %.1f bytes/s, "+
			"want %.1f", got, want)
	}
}