add tests for URL fetching

usbid/load_test.go

@@ -15,7 +15,15 @@
 
 package usbid
 
-import "testing"
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"reflect"
+	"testing"
+)
 
 func TestLoaded(t *testing.T) {
 	if got, min := len(Vendors), 1000; got < min {
@@ -25,3 +33,51 @@ func TestLoaded(t *testing.T) {
 		t.Errorf("%d classes loaded, want at least %d", got, min)
 	}
 }
+
+type handler struct{}
+
+func (handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	f, err := os.Open(testDBPath)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprintf(w, "Open(%q): %v", testDBPath, err)
+		return
+	}
+	defer f.Close()
+	w.Header().Set("content-type", "text/plain")
+	io.Copy(w, f)
+}
+
+func TestLoadFromURL(t *testing.T) {
+	origV, origC := Vendors, Classes
+	Vendors, Classes = nil, nil
+	defer func() { Vendors, Classes = origV, origC }()
+
+	s := httptest.NewServer(handler{})
+	defer s.Close()
+
+	err := LoadFromURL(s.URL)
+	if err != nil {
+		t.Fatalf("LoadFromURL(%q): got unexpected error: %v", s.URL, err)
+	}
+	if !reflect.DeepEqual(Vendors, testDBVendors) {
+		t.Errorf("LoadFromURL Vendors:\ngot: %v\nwant: %v", Vendors, testDBVendors)
+	}
+}
+
+func TestLoadFromURLError(t *testing.T) {
+	origV, origC := Vendors, Classes
+	defer func() { Vendors, Classes = origV, origC }()
+
+	s := httptest.NewServer(http.NotFoundHandler())
+	defer s.Close()
+
+	ts := LastUpdate
+	err := LoadFromURL(s.URL)
+	if err == nil {
+		t.Fatalf("LoadFromURL(%q): err is nil, want not nil", s.URL)
+	}
+	if LastUpdate != ts {
+		t.Errorf("LastUpdate was unexpectedly updated when LoadFromURL failed")
+	}
+}