test: add test cases for HumanNumber (#9108)

format/format_test.go

@@ -12,6 +12,9 @@ func TestHumanNumber(t *testing.T) {
 
 	testCases := []testCase{
 		{0, "0"},
+		{999, "999"},
+		{1000, "1K"},
+		{1001, "1K"},
 		{1000000, "1M"},
 		{125000000, "125M"},
 		{500500000, "500.50M"},