diff --git a/vendor/github.com/golang/mock/gomock/matchers.go b/vendor/github.com/golang/mock/gomock/matchers.go
new file mode 100644
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--- /dev/null
+++ b/vendor/github.com/golang/mock/gomock/matchers.go
@@ -0,0 +1,269 @@
+// Copyright 2010 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gomock
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// A Matcher is a representation of a class of values.
+// It is used to represent the valid or expected arguments to a mocked method.
+type Matcher interface {
+	// Matches returns whether x is a match.
+	Matches(x interface{}) bool
+
+	// String describes what the matcher matches.
+	String() string
+}
+
+// WantFormatter modifies the given Matcher's String() method to the given
+// Stringer. This allows for control on how the "Want" is formatted when
+// printing .
+func WantFormatter(s fmt.Stringer, m Matcher) Matcher {
+	type matcher interface {
+		Matches(x interface{}) bool
+	}
+
+	return struct {
+		matcher
+		fmt.Stringer
+	}{
+		matcher:  m,
+		Stringer: s,
+	}
+}
+
+// StringerFunc type is an adapter to allow the use of ordinary functions as
+// a Stringer. If f is a function with the appropriate signature,
+// StringerFunc(f) is a Stringer that calls f.
+type StringerFunc func() string
+
+// String implements fmt.Stringer.
+func (f StringerFunc) String() string {
+	return f()
+}
+
+// GotFormatter is used to better print failure messages. If a matcher
+// implements GotFormatter, it will use the result from Got when printing
+// the failure message.
+type GotFormatter interface {
+	// Got is invoked with the received value. The result is used when
+	// printing the failure message.
+	Got(got interface{}) string
+}
+
+// GotFormatterFunc type is an adapter to allow the use of ordinary
+// functions as a GotFormatter. If f is a function with the appropriate
+// signature, GotFormatterFunc(f) is a GotFormatter that calls f.
+type GotFormatterFunc func(got interface{}) string
+
+// Got implements GotFormatter.
+func (f GotFormatterFunc) Got(got interface{}) string {
+	return f(got)
+}
+
+// GotFormatterAdapter attaches a GotFormatter to a Matcher.
+func GotFormatterAdapter(s GotFormatter, m Matcher) Matcher {
+	return struct {
+		GotFormatter
+		Matcher
+	}{
+		GotFormatter: s,
+		Matcher:      m,
+	}
+}
+
+type anyMatcher struct{}
+
+func (anyMatcher) Matches(interface{}) bool {
+	return true
+}
+
+func (anyMatcher) String() string {
+	return "is anything"
+}
+
+type eqMatcher struct {
+	x interface{}
+}
+
+func (e eqMatcher) Matches(x interface{}) bool {
+	// In case, some value is nil
+	if e.x == nil || x == nil {
+		return reflect.DeepEqual(e.x, x)
+	}
+
+	// Check if types assignable and convert them to common type
+	x1Val := reflect.ValueOf(e.x)
+	x2Val := reflect.ValueOf(x)
+
+	if x1Val.Type().AssignableTo(x2Val.Type()) {
+		x1ValConverted := x1Val.Convert(x2Val.Type())
+		return reflect.DeepEqual(x1ValConverted.Interface(), x2Val.Interface())
+	}
+
+	return false
+}
+
+func (e eqMatcher) String() string {
+	return fmt.Sprintf("is equal to %v", e.x)
+}
+
+type nilMatcher struct{}
+
+func (nilMatcher) Matches(x interface{}) bool {
+	if x == nil {
+		return true
+	}
+
+	v := reflect.ValueOf(x)
+	switch v.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map,
+		reflect.Ptr, reflect.Slice:
+		return v.IsNil()
+	}
+
+	return false
+}
+
+func (nilMatcher) String() string {
+	return "is nil"
+}
+
+type notMatcher struct {
+	m Matcher
+}
+
+func (n notMatcher) Matches(x interface{}) bool {
+	return !n.m.Matches(x)
+}
+
+func (n notMatcher) String() string {
+	// TODO: Improve this if we add a NotString method to the Matcher interface.
+	return "not(" + n.m.String() + ")"
+}
+
+type assignableToTypeOfMatcher struct {
+	targetType reflect.Type
+}
+
+func (m assignableToTypeOfMatcher) Matches(x interface{}) bool {
+	return reflect.TypeOf(x).AssignableTo(m.targetType)
+}
+
+func (m assignableToTypeOfMatcher) String() string {
+	return "is assignable to " + m.targetType.Name()
+}
+
+type allMatcher struct {
+	matchers []Matcher
+}
+
+func (am allMatcher) Matches(x interface{}) bool {
+	for _, m := range am.matchers {
+		if !m.Matches(x) {
+			return false
+		}
+	}
+	return true
+}
+
+func (am allMatcher) String() string {
+	ss := make([]string, 0, len(am.matchers))
+	for _, matcher := range am.matchers {
+		ss = append(ss, matcher.String())
+	}
+	return strings.Join(ss, "; ")
+}
+
+type lenMatcher struct {
+	i int
+}
+
+func (m lenMatcher) Matches(x interface{}) bool {
+	v := reflect.ValueOf(x)
+	switch v.Kind() {
+	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
+		return v.Len() == m.i
+	default:
+		return false
+	}
+}
+
+func (m lenMatcher) String() string {
+	return fmt.Sprintf("has length %d", m.i)
+}
+
+// Constructors
+
+// All returns a composite Matcher that returns true if and only all of the
+// matchers return true.
+func All(ms ...Matcher) Matcher { return allMatcher{ms} }
+
+// Any returns a matcher that always matches.
+func Any() Matcher { return anyMatcher{} }
+
+// Eq returns a matcher that matches on equality.
+//
+// Example usage:
+//   Eq(5).Matches(5) // returns true
+//   Eq(5).Matches(4) // returns false
+func Eq(x interface{}) Matcher { return eqMatcher{x} }
+
+// Len returns a matcher that matches on length. This matcher returns false if
+// is compared to a type that is not an array, chan, map, slice, or string.
+func Len(i int) Matcher {
+	return lenMatcher{i}
+}
+
+// Nil returns a matcher that matches if the received value is nil.
+//
+// Example usage:
+//   var x *bytes.Buffer
+//   Nil().Matches(x) // returns true
+//   x = &bytes.Buffer{}
+//   Nil().Matches(x) // returns false
+func Nil() Matcher { return nilMatcher{} }
+
+// Not reverses the results of its given child matcher.
+//
+// Example usage:
+//   Not(Eq(5)).Matches(4) // returns true
+//   Not(Eq(5)).Matches(5) // returns false
+func Not(x interface{}) Matcher {
+	if m, ok := x.(Matcher); ok {
+		return notMatcher{m}
+	}
+	return notMatcher{Eq(x)}
+}
+
+// AssignableToTypeOf is a Matcher that matches if the parameter to the mock
+// function is assignable to the type of the parameter to this function.
+//
+// Example usage:
+//   var s fmt.Stringer = &bytes.Buffer{}
+//   AssignableToTypeOf(s).Matches(time.Second) // returns true
+//   AssignableToTypeOf(s).Matches(99) // returns false
+//
+//   var ctx = reflect.TypeOf((*context.Context)(nil)).Elem()
+//   AssignableToTypeOf(ctx).Matches(context.Background()) // returns true
+func AssignableToTypeOf(x interface{}) Matcher {
+	if xt, ok := x.(reflect.Type); ok {
+		return assignableToTypeOfMatcher{xt}
+	}
+	return assignableToTypeOfMatcher{reflect.TypeOf(x)}
+}