Adding initial file structure and list def rules
diff --git a/openstack/compute/v2/extensions/defsecrules/fixtures.go b/openstack/compute/v2/extensions/defsecrules/fixtures.go
new file mode 100644
index 0000000..0b11338
--- /dev/null
+++ b/openstack/compute/v2/extensions/defsecrules/fixtures.go
@@ -0,0 +1,38 @@
+package defsecrules
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	th "github.com/rackspace/gophercloud/testhelper"
+	fake "github.com/rackspace/gophercloud/testhelper/client"
+)
+
+const rootPath = "/os-security-group-default-rules"
+
+func mockListRulesResponse(t *testing.T) {
+	th.Mux.HandleFunc(rootPath, 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, `
+{
+  "security_group_default_rules": [
+    {
+      "from_port": 80,
+      "id": "f9a97fcf-3a97-47b0-b76f-919136afb7ed",
+      "ip_protocol": "TCP",
+      "ip_range": {
+        "cidr": "10.10.10.0/24"
+      },
+      "to_port": 80
+    }
+  ]
+}
+      `)
+	})
+}