Trying to add benchmarks but something is broken

time_test.go

@@ -1,40 +1,88 @@
 package cstrftime
 
 import (
+	"fmt"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
 func TestFormat(t *testing.T) {
-	tm := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC)
+	tm := time.Date(2000, 2, 1, 16, 30, 22, 123456789, time.UTC)
 
-	t.Run("weekday as locale’s abbreviated name", func(t *testing.T) {
-		assert.Equal(t, "Tue", Format("%a", tm))
-	})
+	cases := []struct {
+		name, format, result string
+	}{
+		{"weekday as locale’s abbreviated name", "%a", "Tue"},
+		{"weekday as locale’s full name", "%A", "Tuesday"},
+		{"weekday as a decimal number", "%w", "2"},
+		{"day of the month as a zero-padded decimal number", "%d", "01"},
+		{"month as locale’s abbreviated name", "%b", "Feb"},
+		{"month as locale’s full name", "%B", "February"},
+		{"month as a zero-padded decimal number", "%m", "02"},
+		{"24 hour Hours", "%H", "16"},
+		{"12 hour Hours", "%I", "04"},
+		{"Minutes", "%M", "30"},
+		{"Seconds", "%S", "22"},
+		{"seconds with decimals", "%S.%f", "22.123456"},
+		{"american date", "%m/%d/%Y", "02/01/2000"},
+		{"proper date", "%Y/%m/%d", "2000/02/01"},
+		{"dashed date", "%Y-%m-%d", "2000-02-01"},
+	}
 
-	t.Run("weekday as locale’s full name", func(t *testing.T) {
-		assert.Equal(t, "Tuesday", Format("%A", tm))
-	})
+	for _, c := range cases {
+		c := c
 
-	t.Run("weekday as a decimal number", func(t *testing.T) {
-		assert.Equal(t, "2", Format("%w", tm))
-	})
+		t.Run(c.name, func(t *testing.T) {
+			assert.Equal(t, c.result, Format(c.format, tm))
+		})
+	}
+}
+
+func BenchmarkFormat(b *testing.B) {
+	tm := time.Date(2000, time.February, 13, 16, 30, 20, 12345, time.UTC)
+
+	cases := []struct {
+		name, cFormat, goFormat string
+	}{
+		{"year", "%Y", "2006"},
+		{"date", "%Y/%m/%d", "2006/01/02"},
+	}
+
+	for _, c := range cases {
+		assert.Equal(b, tm.Format(c.goFormat), Format(c.cFormat, tm), c.name)
+	}
 
-	t.Run("day of the month as a zero-padded decimal number", func(t *testing.T) {
-		assert.Equal(t, "01", Format("%d", tm))
-	})
+	for _, c := range cases {
+		for _, native := range []bool{true, false} {
+			c := c
+			native := native
 
-	t.Run("month as locale’s abbreviated name", func(t *testing.T) {
-		assert.Equal(t, "Feb", Format("%b", tm))
-	})
+			b.Run(fmt.Sprintf("%s - native(%t)", c.name, native), func(b *testing.B) {
+				var (
+					want = tm.Format(c.goFormat)
+					got  string
+				)
 
-	t.Run("month as locale’s full name", func(t *testing.T) {
-		assert.Equal(t, "February", Format("%B", tm))
-	})
+				switch native {
+				case true:
+					b.ResetTimer()
+					for i := 0; i < b.N; i++ {
+						if got = tm.Format(c.goFormat); want != got {
+							b.Fatalf("want: %q got: %q", want, got)
+						}
+					}
 
-	t.Run("month as a zero-padded decimal number", func(t *testing.T) {
-		assert.Equal(t, "02", Format("%m", tm))
-	})
+				case false:
+					b.ResetTimer()
+					for i := 0; i < b.N; i++ {
+						if got = Format(c.cFormat, tm); want != got {
+							b.Fatalf("want: %q got: %q", want, got)
+						}
+					}
+				}
+			})
+		}
+	}
 }