VOL-1868 move simulated onu from voltha-go to voltha-simonu-adapter

Sourced from voltha-go commit 251a11c0ffe60512318a644cd6ce0dc4e12f4018

Change-Id: Iab179bc2f3dd772ed7f488d1c03d1a84ba75e874
diff --git a/vendor/github.com/stretchr/testify/assert/errors.go b/vendor/github.com/stretchr/testify/assert/errors.go
new file mode 100644
index 0000000..ac9dc9d
--- /dev/null
+++ b/vendor/github.com/stretchr/testify/assert/errors.go
@@ -0,0 +1,10 @@
+package assert
+
+import (
+	"errors"
+)
+
+// AnError is an error instance useful for testing.  If the code does not care
+// about error specifics, and only needs to return the error for example, this
+// error should be used to make the test code more readable.
+var AnError = errors.New("assert.AnError general error for testing")