Adjust style of EquateApproxTime (#177)

Adjust coding style of EquateApproxTime to match EquateApprox.

2 files changed, 43 insertions, 41 deletions

diff --git a/cmp/cmpopts/equate.go b/cmp/cmpopts/equate.go
index fea57bc..343dcf9 100644
--- a/cmp/cmpopts/equate.go
+++ b/cmp/cmpopts/equate.go
@@ -89,23 +89,20 @@ func areNaNsF32s(x, y float32) bool {
 	return areNaNsF64s(float64(x), float64(y))
 }
 
-// EquateApproxTime returns a Comparer options that
-// determine two time.Time values to be equal if they
-// are within the given time interval of one another.
-// Note that if both times have a monotonic clock reading,
-// the monotonic time difference will be used.
-//
-// The zero time is treated specially: it is only considered
-// equal to another zero time value.
-//
-// It will panic if margin is negative.
+// EquateApproxTime returns a Comparer option that determines two non-zero
+// time.Time values to be equal if they are within some margin of one another.
+// If both times have a monotonic clock reading, then the monotonic time
+// difference will be used. The margin must be non-negative.
 func EquateApproxTime(margin time.Duration) cmp.Option {
 	if margin < 0 {
-		panic("negative duration in EquateApproxTime")
+		panic("margin must be a non-negative number")
 	}
-	return cmp.FilterValues(func(x, y time.Time) bool {
-		return !x.IsZero() && !y.IsZero()
-	}, cmp.Comparer(timeApproximator{margin}.compare))
+	a := timeApproximator{margin}
+	return cmp.FilterValues(areNonZeroTimes, cmp.Comparer(a.compare))
+}
+
+func areNonZeroTimes(x, y time.Time) bool {
+	return !x.IsZero() && !y.IsZero()
 }
 
 type timeApproximator struct {
diff --git a/cmp/cmpopts/util_test.go b/cmp/cmpopts/util_test.go
index 3c01cac..e80c963 100644
--- a/cmp/cmpopts/util_test.go
+++ b/cmp/cmpopts/util_test.go
@@ -472,17 +472,19 @@ func TestOptions(t *testing.T) {
 		wantEqual: true,
 		reason:    "equal because time is exactly at the allowed margin (negative)",
 	}, {
-		label:  "EquateApproxTime",
-		x:      time.Date(2009, 11, 10, 23, 0, 3, 0, time.UTC),
-		y:      time.Date(2009, 11, 10, 23, 0, 0, 0, time.UTC),
-		opts:   []cmp.Option{EquateApproxTime(3*time.Second - 1)},
-		reason: "not equal because time is outside allowed margin",
-	}, {
-		label:  "EquateApproxTime",
-		x:      time.Date(2009, 11, 10, 23, 0, 0, 0, time.UTC),
-		y:      time.Date(2009, 11, 10, 23, 0, 3, 0, time.UTC),
-		opts:   []cmp.Option{EquateApproxTime(3*time.Second - 1)},
-		reason: "not equal because time is outside allowed margin (negative)",
+		label:     "EquateApproxTime",
+		x:         time.Date(2009, 11, 10, 23, 0, 3, 0, time.UTC),
+		y:         time.Date(2009, 11, 10, 23, 0, 0, 0, time.UTC),
+		opts:      []cmp.Option{EquateApproxTime(3*time.Second - 1)},
+		wantEqual: false,
+		reason:    "not equal because time is outside allowed margin",
+	}, {
+		label:     "EquateApproxTime",
+		x:         time.Date(2009, 11, 10, 23, 0, 0, 0, time.UTC),
+		y:         time.Date(2009, 11, 10, 23, 0, 3, 0, time.UTC),
+		opts:      []cmp.Option{EquateApproxTime(3*time.Second - 1)},
+		wantEqual: false,
+		reason:    "not equal because time is outside allowed margin (negative)",
 	}, {
 		label:     "EquateApproxTime",
 		x:         time.Time{},
@@ -491,23 +493,26 @@ func TestOptions(t *testing.T) {
 		wantEqual: true,
 		reason:    "equal because both times are zero",
 	}, {
-		label:  "EquateApproxTime",
-		x:      time.Time{},
-		y:      time.Time{}.Add(1),
-		opts:   []cmp.Option{EquateApproxTime(3 * time.Second)},
-		reason: "not equal because zero time is always not equal not non-zero",
+		label:     "EquateApproxTime",
+		x:         time.Time{},
+		y:         time.Time{}.Add(1),
+		opts:      []cmp.Option{EquateApproxTime(3 * time.Second)},
+		wantEqual: false,
+		reason:    "not equal because zero time is always not equal not non-zero",
 	}, {
-		label:  "EquateApproxTime",
-		x:      time.Time{}.Add(1),
-		y:      time.Time{},
-		opts:   []cmp.Option{EquateApproxTime(3 * time.Second)},
-		reason: "not equal because zero time is always not equal not non-zero",
+		label:     "EquateApproxTime",
+		x:         time.Time{}.Add(1),
+		y:         time.Time{},
+		opts:      []cmp.Option{EquateApproxTime(3 * time.Second)},
+		wantEqual: false,
+		reason:    "not equal because zero time is always not equal not non-zero",
 	}, {
-		label:  "EquateApproxTime",
-		x:      time.Date(2409, 11, 10, 23, 0, 0, 0, time.UTC),
-		y:      time.Date(2000, 11, 10, 23, 0, 3, 0, time.UTC),
-		opts:   []cmp.Option{EquateApproxTime(3 * time.Second)},
-		reason: "time difference overflows time.Duration",
+		label:     "EquateApproxTime",
+		x:         time.Date(2409, 11, 10, 23, 0, 0, 0, time.UTC),
+		y:         time.Date(2000, 11, 10, 23, 0, 3, 0, time.UTC),
+		opts:      []cmp.Option{EquateApproxTime(3 * time.Second)},
+		wantEqual: false,
+		reason:    "time difference overflows time.Duration",
 	}, {
 		label:     "IgnoreFields",
 		x:         Bar1{Foo3{&Foo2{&Foo1{Alpha: 5}}}},
@@ -950,7 +955,7 @@ func TestPanic(t *testing.T) {
 		label:     "EquateApproxTime",
 		fnc:       EquateApproxTime,
 		args:      args(time.Duration(-1)),
-		wantPanic: "negative duration in EquateApproxTime",
+		wantPanic: "margin must be a non-negative number",
 		reason:    "negative duration is invalid",
 	}, {
 		label:     "SortSlices",