From 70a0403b6d3a167c4101cbe884fab83a05227c05 Mon Sep 17 00:00:00 2001
From: Jason Hall <imjasonh@gmail.com>
Date: Thu, 5 Mar 2015 13:36:26 -0500
Subject: [PATCH] Proactively fail if SnapToRoads is called without an API key

---
 maps_test.go | 12 ++++++++----
 roads.go     |  7 +++++++
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/maps_test.go b/maps_test.go
index 346f9b8..ee44709 100644
--- a/maps_test.go
+++ b/maps_test.go
@@ -11,7 +11,7 @@ import (
 var (
 	apiKey = flag.String("apiKey", "", "Google Maps API key")
 
-	ctx  = NewContext("key", &http.Client{})
+	ctx  = NewContext("", &http.Client{})
 	wctx = NewWorkContext("clientID", "privKey", &http.Client{})
 )
 
@@ -184,8 +184,6 @@ func TestDistanceMatrix(t *testing.T) {
 }
 
 func TestSnapToRoads(t *testing.T) {
-	ctx = NewContext(*apiKey, &http.Client{})
-
 	path := []LatLng{{-35.27801, 149.12958},
 		{-35.28032, 149.12907},
 		{-35.28099, 149.12929},
@@ -197,7 +195,13 @@ func TestSnapToRoads(t *testing.T) {
 	opts := &SnapToRoadsOpts{
 		Interpolate: true,
 	}
-	r, err := SnapToRoads(ctx, path, opts)
+
+	if _, err := SnapToRoads(ctx, path, opts); err != ErrNoAPIKey {
+		t.Errorf("unexpected error, got %v, want %v", err, ErrNoAPIKey)
+	}
+
+	keyCtx := NewContext(*apiKey, &http.Client{})
+	r, err := SnapToRoads(keyCtx, path, opts)
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
diff --git a/roads.go b/roads.go
index d06de9c..0f163f8 100644
--- a/roads.go
+++ b/roads.go
@@ -1,6 +1,7 @@
 package maps
 
 import (
+	"errors"
 	"net/url"
 
 	"code.google.com/p/go.net/context"
@@ -8,7 +9,13 @@ import (
 
 const roadsAPIBaseURL = "https://roads.googleapis.com/v1/"
 
+var ErrNoAPIKey = errors.New("must provide an API key")
+
 func SnapToRoads(ctx context.Context, path []LatLng, opts *SnapToRoadsOpts) ([]SnappedPoint, error) {
+	if key(ctx) == "" {
+		return nil, ErrNoAPIKey
+	}
+
 	var d snapToRoadsResponse
 	if err := doDecode(ctx, roadsAPIBaseURL+snapToRoads(path, opts), &d); err != nil {
 		return nil, err