size_test: add parseSize benchmark

Shows on my laptop (6 iterations processed by benchstat):

name         time/op
ParseSize-4  10.6µs ± 3%

name         alloc/op
ParseSize-4  3.26kB ± 0%

name         allocs/op
ParseSize-4    72.0 ± 0%

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

size_test.go

@@ -140,6 +140,18 @@ func TestRAMInBytes(t *testing.T) {
 	assertError(t, RAMInBytes, "32bm")
 }
 
+func BenchmarkParseSize(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, s := range []string{
+			"", "32", "32b", "32 B", "32k", "32.5 K", "32kb", "32 Kb",
+			"32.8Mb", "32.9Gb", "32.777Tb", "32Pb", "0.3Mb", "-1",
+		} {
+			FromHumanSize(s)
+			RAMInBytes(s)
+		}
+	}
+}
+
 func assertEquals(t *testing.T, expected, actual interface{}) {
 	if expected != actual {
 		t.Errorf("Expected '%v' but got '%v'", expected, actual)