net/http/httputil: add tests for singleJoiningSlash.

These changes add tests for the unexported function singleJoiningSlash.

Change-Id: I107905aac4a3c2544be309098b67e970ea5b542c
GitHub-Last-Rev: ed6f86f619549f46ef53316b7febaac781b64e4b
GitHub-Pull-Request: golang/go#29088
Reviewed-on: https://go-review.googlesource.com/c/152337Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/http/httputil/reverseproxy_test.go

@@ -7,23 +7,23 @@
 package httputil
 
 import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
-	"testing"
-	"time"
+	"os"
 	"reflect"
-	"io"
+	"strconv"
 	"strings"
-	"bufio"
 	"sync"
-	"strconv"
-	"bytes"
-	"errors"
-	"fmt"
-	"os"
+	"testing"
+	"time"
 )
 
 const fakeHopHeader = "X-Fake-Hop-Header-For-Test"
@@ -1078,3 +1078,26 @@ func TestUnannouncedTrailer(t *testing.T) {
 	}
 
 }
+
+func TestSingleJoinSlash(t *testing.T) {
+	tests := []struct {
+		slasha   string
+		slashb   string
+		expected string
+	}{
+		{"https://www.google.com/", "/favicon.ico", "https://www.google.com/favicon.ico"},
+		{"https://www.google.com", "/favicon.ico", "https://www.google.com/favicon.ico"},
+		{"https://www.google.com", "favicon.ico", "https://www.google.com/favicon.ico"},
+		{"https://www.google.com", "", "https://www.google.com/"},
+		{"", "favicon.ico", "/favicon.ico"},
+	}
+	for _, tt := range tests {
+		if got := singleJoiningSlash(tt.slasha, tt.slashb); got != tt.expected {
+			t.Errorf("singleJoiningSlash(%s,%s) want %s got %s",
+				tt.slasha,
+				tt.slashb,
+				tt.expected,
+				got)
+		}
+	}
+}