Update test style to checker

ethutil/size_test.go

@@ -17,19 +17,7 @@ func (s *SizeSuite) TestStorageSizeString(c *checker.C) {
 	exp2 := "2.19 kB"
 	exp3 := "12.00 B"
 
-	res1 := StorageSize(data1).String()
-	res2 := StorageSize(data2).String()
-	res3 := StorageSize(data3).String()
-
-	if res1 != exp1 {
-		t.Errorf("Expected %s got %s", exp1, res1)
-	}
-
-	if res2 != exp2 {
-		t.Errorf("Expected %s got %s", exp2, res2)
-	}
-
-	if res3 != exp3 {
-		t.Errorf("Expected %s got %s", exp3, res3)
-	}
+	c.Assert(StorageSize(data1).String(), checker.Equals, exp1)
+	c.Assert(StorageSize(data2).String(), checker.Equals, exp2)
+	c.Assert(StorageSize(data3).String(), checker.Equals, exp3)
 }