Add a package listing API to cipd.

go/src/infra/tools/cipd/remote_test.go

Index: go/src/infra/tools/cipd/remote_test.go
diff --git a/go/src/infra/tools/cipd/remote_test.go b/go/src/infra/tools/cipd/remote_test.go
index e5b4bb43c375ea132b4a8ccbd8071cae1a1b5538..ab1fbd3dece9398919992bc7e4c1e124fbda470e 100644
--- a/go/src/infra/tools/cipd/remote_test.go
+++ b/go/src/infra/tools/cipd/remote_test.go
@@ -93,6 +93,18 @@ func TestRemoteImpl(t *testing.T) {
 		return remote.modifyACL("pkgname", changes)
 	}
 
+	mockListPackages := func(c C, reply string) ([]string, error) {
+		remote := mockRemoteImpl(c, []expectedHTTPCall{
+			{
+				Method: "GET",
+				Path:   "/_ah/api/repo/v1/packages",
+				Query:  url.Values{"prefix": []string{"pkgprefix"}},
+				Reply:  reply,
+			},
+		})
+		return remote.listPackages("pkgprefix")
+	}
+
 	mockAttachTags := func(c C, tags []string, body, reply string) error {
 		remote := mockRemoteImpl(c, []expectedHTTPCall{
 			{
@@ -477,6 +489,30 @@ func TestRemoteImpl(t *testing.T) {
 		So(err, ShouldNotBeNil)
 	})
 
+	Convey("listPackages SUCCESS", t, func(c C) {
+		result, err := mockListPackages(c, `{
+				"status": "SUCCESS",
+				"packages": [
+					"pkgprefix/fake1",
+					"pkgprefix/fake2"
+				]
+			}`)
+		So(err, ShouldBeNil)
+		So(result, ShouldResemble, []string{
+			"pkgprefix/fake1",
+			"pkgprefix/fake2",
+		})
+	})
+
+	Convey("listPackages ERROR", t, func(c C) {
+		result, err := mockListPackages(c, `{
+				"status": "ERROR",
+				"error_message": "Some error message"
+			}`)
+		So(err, ShouldNotBeNil)
+		So(result, ShouldBeNil)
+	})
+
 	Convey("attachTags SUCCESS", t, func(c C) {
 		err := mockAttachTags(
 			c, []string{"tag1:value1", "tag2:value2"},