Add handling of comments in targets.txt

Skips lines that start with `//`, to allow commments in `targets.txt`. This is
handy when you want to attach a comment on why a specific endpoint is tested, in
a `targets.txt` used as part of a benchmark suite.

lib/targets.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"fmt"
 	"io"
+  "regexp"
 	"math/rand"
 	"net/http"
 	"os"
@@ -29,10 +30,10 @@ func readTargets(source io.Reader) (Targets, error) {
 	lines := make([]string, 0)
 	for scanner.Scan() {
 		line := scanner.Text()
-		if line = strings.TrimSpace(line); line == "" { // Empty line
-			continue
+
+		if !skipLine(line) { // Not a comment or blank line
+      lines = append(lines, line)
 		}
-		lines = append(lines, line)
 	}
 	if err := scanner.Err(); err != nil {
 		return Targets{}, err
@@ -41,6 +42,10 @@ func readTargets(source io.Reader) (Targets, error) {
 	return NewTargets(lines)
 }
 
+func skipLine(line string) (bool) {
+  return regexp.MustCompile(`^\s*((\/\/)|$)`).MatchString(line)
+}
+
 // NewTargets instantiates Targets from a slice of strings
 func NewTargets(lines []string) (Targets, error) {
 	targets := make([]*http.Request, 0)

lib/targets_test.go

@@ -7,7 +7,7 @@ import (
 )
 
 func TestReadTargets(t *testing.T) {
-	lines := bytes.NewBufferString("GET http://lolcathost:9999/\n\nHEAD http://lolcathost:9999/\n")
+  lines := bytes.NewBufferString("GET http://lolcathost:9999/\n\n      // HEAD http://lolcathost.com this is a comment \nHEAD http://lolcathost:9999/\n")
 	targets, err := readTargets(lines)
 	if err != nil {
 		t.Fatalf("Couldn't parse valid source: %s", err)