Address review comments

changelog/unreleased/issue-3397

@@ -1,13 +1,6 @@
-# The first line must start with Bugfix:, Enhancement: or Change:,
-# including the colon. Use present use. Remove lines starting with '#'
-# from this template.
 Enhancement: Improve the ETA displayed during backup
 
-# Describe the problem in the past tense, the new behavior in the present
-# tense. Mention the affected commands, backends, operating systems, etc.
-# Focus on user-facing behavior, not the implementation.
-
-Restic's backup command displayed an ETA that did not adapt when the rate
+Restic's `backup` command displayed an ETA that did not adapt when the rate
 of progress made during the backup changed during the course of the
 backup. Restic now uses recent progress when computing the ETA. It is
 important to realize that the estimate may still be wrong, because restic
@@ -15,3 +8,4 @@ cannot predict the future, but the hope is that the ETA will be more
 accurate in most cases.
 
 https://github.com/restic/restic/issues/3397
+https://github.com/restic/restic/pull/3563

internal/ui/backup/progress.go

@@ -76,7 +76,8 @@ func NewProgress(printer ProgressPrinter, interval time.Duration) *Progress {
 			var secondsRemaining uint64
 			if p.scanFinished {
 				rate := p.estimator.rate(time.Now())
-				if rate <= 0 {
+				tooSlowCutoff := 1024.
+				if rate <= tooSlowCutoff {
 					secondsRemaining = 0
 				} else {
 					todo := float64(p.total.Bytes - p.processed.Bytes)

internal/ui/backup/rate_estimator.go

@@ -18,7 +18,7 @@ type rateEstimator struct {
 	totalBytes uint64
 }
 
-// newRateEstimator returns an esimator initialized to a presumed start time.
+// newRateEstimator returns an estimator initialized to a presumed start time.
 func newRateEstimator(start time.Time) *rateEstimator {
 	return &rateEstimator{buckets: list.New(), start: start}
 }

internal/ui/backup/rate_estimator_test.go

@@ -1,9 +1,12 @@
 package backup
 
 import (
+	"fmt"
 	"math"
 	"testing"
 	"time"
+
+	rtest "github.com/restic/restic/internal/test"
 )
 
 const float64EqualityThreshold = 1e-6
@@ -19,17 +22,13 @@ func TestEstimatorDefault(t *testing.T) {
 	var start time.Time
 	e := newRateEstimator(start)
 	r := e.rate(start)
-	if math.IsNaN(r) || r != 0 {
-		t.Fatalf("e.Rate == %v, want zero", r)
-	}
+	rtest.Assert(t, r == 0, "e.Rate == %v, want zero", r)
 	r = e.rate(start.Add(time.Hour))
-	if math.IsNaN(r) || r != 0 {
-		t.Fatalf("e.Rate == %v, want zero", r)
-	}
+	rtest.Assert(t, r == 0, "e.Rate == %v, want zero", r)
 }
 
 func TestEstimatorSimple(t *testing.T) {
-	var when time.Time
+	var start time.Time
 	type testcase struct {
 		bytes uint64
 		when  time.Duration
@@ -43,12 +42,13 @@ func TestEstimatorSimple(t *testing.T) {
 		{60, time.Minute, 1},
 	}
 	for _, c := range cases {
-		e := newRateEstimator(when)
-		e.recordBytes(when.Add(time.Second), c.bytes)
-		rate := e.rate(when.Add(c.when))
-		if !almostEqual(rate, c.rate) {
-			t.Fatalf("e.Rate == %v, want %v (testcase %+v)", rate, c.rate, c)
-		}
+		name := fmt.Sprintf("%+v", c)
+		t.Run(name, func(t *testing.T) {
+			e := newRateEstimator(start)
+			e.recordBytes(start.Add(time.Second), c.bytes)
+			rate := e.rate(start.Add(c.when))
+			rtest.Assert(t, almostEqual(rate, c.rate), "e.Rate == %v, want %v", rate, c.rate)
+		})
 	}
 }
 
@@ -60,42 +60,27 @@ func TestBucketWidth(t *testing.T) {
 	e := newRateEstimator(when)
 	e.recordBytes(when, 1)
 	e.recordBytes(when.Add(bucketWidth-time.Nanosecond), 1)
-	if e.buckets.Len() != 1 {
-		t.Fatalf("e.buckets.Len() is %d, want 1", e.buckets.Len())
-	}
+	rtest.Assert(t, e.buckets.Len() == 1, "e.buckets.Len() is %d, want 1", e.buckets.Len())
+
 	b := e.buckets.Back().Value.(*rateBucket)
-	if b.totalBytes != 2 {
-		t.Fatalf("b.totalBytes is %d, want 2", b.totalBytes)
-	}
-	if b.end != when.Add(bucketWidth) {
-		t.Fatalf("b.end is %v, want %v", b.end, when.Add(bucketWidth))
-	}
+	rtest.Assert(t, b.totalBytes == 2, "b.totalBytes is %d, want 2", b.totalBytes)
+	rtest.Assert(t, b.end == when.Add(bucketWidth), "b.end is %v, want %v", b.end, when.Add(bucketWidth))
 
 	// Recording a byte outside the bucket width causes another bucket.
 	e.recordBytes(when.Add(bucketWidth), 1)
-	if e.buckets.Len() != 2 {
-		t.Fatalf("e.buckets.Len() is %d, want 2", e.buckets.Len())
-	}
+	rtest.Assert(t, e.buckets.Len() == 2, "e.buckets.Len() is %d, want 2", e.buckets.Len())
+
 	b = e.buckets.Back().Value.(*rateBucket)
-	if b.totalBytes != 1 {
-		t.Fatalf("b.totalBytes is %d, want 1", b.totalBytes)
-	}
-	if b.end != when.Add(2*bucketWidth) {
-		t.Fatalf("b.end is %v, want %v", b.end, when.Add(bucketWidth))
-	}
+	rtest.Assert(t, b.totalBytes == 1, "b.totalBytes is %d, want 1", b.totalBytes)
+	rtest.Assert(t, b.end == when.Add(2*bucketWidth), "b.end is %v, want %v", b.end, when.Add(bucketWidth))
 
 	// Recording a byte after a longer delay creates a sparse bucket list.
 	e.recordBytes(when.Add(time.Hour+time.Millisecond), 7)
-	if e.buckets.Len() != 3 {
-		t.Fatalf("e.buckets.Len() is %d, want 3", e.buckets.Len())
-	}
+	rtest.Assert(t, e.buckets.Len() == 3, "e.buckets.Len() is %d, want 3", e.buckets.Len())
+
 	b = e.buckets.Back().Value.(*rateBucket)
-	if b.totalBytes != 7 {
-		t.Fatalf("b.totalBytes is %d, want 7", b.totalBytes)
-	}
-	if b.end != when.Add(time.Hour+time.Millisecond+time.Second) {
-		t.Fatalf("b.end is %v, want %v", b.end, when.Add(time.Hour+time.Millisecond+time.Second))
-	}
+	rtest.Assert(t, b.totalBytes == 7, "b.totalBytes is %d, want 7", b.totalBytes)
+	rtest.Equals(t, when.Add(time.Hour+time.Millisecond+time.Second), b.end)
 }
 
 type chunk struct {
@@ -103,17 +88,12 @@ type chunk struct {
 	bytes       uint64 // byte count (every second)
 }
 
-func applyChunk(c chunk, t time.Time, e *rateEstimator) time.Time {
-	for i := uint64(0); i < c.repetitions; i++ {
-		e.recordBytes(t, c.bytes)
-		t = t.Add(time.Second)
-	}
-	return t
-}
-
 func applyChunks(chunks []chunk, t time.Time, e *rateEstimator) time.Time {
 	for _, c := range chunks {
-		t = applyChunk(c, t, e)
+		for i := uint64(0); i < c.repetitions; i++ {
+			e.recordBytes(t, c.bytes)
+			t = t.Add(time.Second)
+		}
 	}
 	return t
 }
@@ -221,13 +201,13 @@ func TestEstimatorResponsiveness(t *testing.T) {
 		},
 	}
 
-	for i, c := range cases {
-		var w time.Time
-		e := newRateEstimator(w)
-		w = applyChunks(c.chunks, w, e)
-		r := e.rate(w)
-		if !almostEqual(r, c.rate) {
-			t.Fatalf("e.Rate == %f, want %f (testcase %d %+v)", r, c.rate, i, c)
-		}
+	for _, c := range cases {
+		t.Run(c.description, func(t *testing.T) {
+			var w time.Time
+			e := newRateEstimator(w)
+			w = applyChunks(c.chunks, w, e)
+			r := e.rate(w)
+			rtest.Assert(t, almostEqual(r, c.rate), "e.Rate == %f, want %f", r, c.rate)
+		})
 	}
 }