add additional test and further rework client mocks

pkg/container/mocks/container_ref.go

@@ -0,0 +1,42 @@
+package mocks
+
+import (
+	"fmt"
+	"os"
+
+	t "github.com/containrrr/watchtower/pkg/types"
+)
+
+type imageRef struct {
+	id   t.ImageID
+	file string
+}
+
+func (ir *imageRef) getFileName() string {
+	return fmt.Sprintf("./mocks/data/image_%v.json", ir.file)
+}
+
+type ContainerRef struct {
+	name       string
+	id         t.ContainerID
+	image      *imageRef
+	file       string
+	references []*ContainerRef
+	isMissing  bool
+}
+
+func (cr *ContainerRef) getContainerFile() (containerFile string, err error) {
+	file := cr.file
+	if file == "" {
+		file = cr.name
+	}
+
+	containerFile = fmt.Sprintf("./mocks/data/container_%v.json", file)
+	_, err = os.Stat(containerFile)
+
+	return containerFile, err
+}
+
+func (cr *ContainerRef) ContainerID() t.ContainerID {
+	return cr.id
+}