Adding list roles operation
diff --git a/openstack/identity/v2/extensions/admin/roles/fixtures.go b/openstack/identity/v2/extensions/admin/roles/fixtures.go
new file mode 100644
index 0000000..04fccd7
--- /dev/null
+++ b/openstack/identity/v2/extensions/admin/roles/fixtures.go
@@ -0,0 +1,32 @@
+package roles
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	th "github.com/rackspace/gophercloud/testhelper"
+	fake "github.com/rackspace/gophercloud/testhelper/client"
+)
+
+func MockListRoleResponse(t *testing.T) {
+	th.Mux.HandleFunc("/OS-KSADMN/roles", func(w http.ResponseWriter, r *http.Request) {
+		th.TestMethod(t, r, "GET")
+		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
+
+		w.Header().Add("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+
+		fmt.Fprintf(w, `
+{
+    "roles": [
+        {
+            "id": "123",
+            "name": "compute:admin",
+            "description": "Nova Administrator"
+        }
+    ]
+}
+  `)
+	})
+}