diff --git a/vendor/github.com/golang/mock/gomock/call.go b/vendor/github.com/golang/mock/gomock/call.go
new file mode 100644
index 0000000..7345f65
--- /dev/null
+++ b/vendor/github.com/golang/mock/gomock/call.go
@@ -0,0 +1,427 @@
+// 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"
+	"strconv"
+	"strings"
+)
+
+// Call represents an expected call to a mock.
+type Call struct {
+	t TestHelper // for triggering test failures on invalid call setup
+
+	receiver   interface{}  // the receiver of the method call
+	method     string       // the name of the method
+	methodType reflect.Type // the type of the method
+	args       []Matcher    // the args
+	origin     string       // file and line number of call setup
+
+	preReqs []*Call // prerequisite calls
+
+	// Expectations
+	minCalls, maxCalls int
+
+	numCalls int // actual number made
+
+	// actions are called when this Call is called. Each action gets the args and
+	// can set the return values by returning a non-nil slice. Actions run in the
+	// order they are created.
+	actions []func([]interface{}) []interface{}
+}
+
+// newCall creates a *Call. It requires the method type in order to support
+// unexported methods.
+func newCall(t TestHelper, receiver interface{}, method string, methodType reflect.Type, args ...interface{}) *Call {
+	t.Helper()
+
+	// TODO: check arity, types.
+	margs := make([]Matcher, len(args))
+	for i, arg := range args {
+		if m, ok := arg.(Matcher); ok {
+			margs[i] = m
+		} else if arg == nil {
+			// Handle nil specially so that passing a nil interface value
+			// will match the typed nils of concrete args.
+			margs[i] = Nil()
+		} else {
+			margs[i] = Eq(arg)
+		}
+	}
+
+	origin := callerInfo(3)
+	actions := []func([]interface{}) []interface{}{func([]interface{}) []interface{} {
+		// Synthesize the zero value for each of the return args' types.
+		rets := make([]interface{}, methodType.NumOut())
+		for i := 0; i < methodType.NumOut(); i++ {
+			rets[i] = reflect.Zero(methodType.Out(i)).Interface()
+		}
+		return rets
+	}}
+	return &Call{t: t, receiver: receiver, method: method, methodType: methodType,
+		args: margs, origin: origin, minCalls: 1, maxCalls: 1, actions: actions}
+}
+
+// AnyTimes allows the expectation to be called 0 or more times
+func (c *Call) AnyTimes() *Call {
+	c.minCalls, c.maxCalls = 0, 1e8 // close enough to infinity
+	return c
+}
+
+// MinTimes requires the call to occur at least n times. If AnyTimes or MaxTimes have not been called or if MaxTimes
+// was previously called with 1, MinTimes also sets the maximum number of calls to infinity.
+func (c *Call) MinTimes(n int) *Call {
+	c.minCalls = n
+	if c.maxCalls == 1 {
+		c.maxCalls = 1e8
+	}
+	return c
+}
+
+// MaxTimes limits the number of calls to n times. If AnyTimes or MinTimes have not been called or if MinTimes was
+// previously called with 1, MaxTimes also sets the minimum number of calls to 0.
+func (c *Call) MaxTimes(n int) *Call {
+	c.maxCalls = n
+	if c.minCalls == 1 {
+		c.minCalls = 0
+	}
+	return c
+}
+
+// DoAndReturn declares the action to run when the call is matched.
+// The return values from this function are returned by the mocked function.
+// It takes an interface{} argument to support n-arity functions.
+func (c *Call) DoAndReturn(f interface{}) *Call {
+	// TODO: Check arity and types here, rather than dying badly elsewhere.
+	v := reflect.ValueOf(f)
+
+	c.addAction(func(args []interface{}) []interface{} {
+		vargs := make([]reflect.Value, len(args))
+		ft := v.Type()
+		for i := 0; i < len(args); i++ {
+			if args[i] != nil {
+				vargs[i] = reflect.ValueOf(args[i])
+			} else {
+				// Use the zero value for the arg.
+				vargs[i] = reflect.Zero(ft.In(i))
+			}
+		}
+		vrets := v.Call(vargs)
+		rets := make([]interface{}, len(vrets))
+		for i, ret := range vrets {
+			rets[i] = ret.Interface()
+		}
+		return rets
+	})
+	return c
+}
+
+// Do declares the action to run when the call is matched. The function's
+// return values are ignored to retain backward compatibility. To use the
+// return values call DoAndReturn.
+// It takes an interface{} argument to support n-arity functions.
+func (c *Call) Do(f interface{}) *Call {
+	// TODO: Check arity and types here, rather than dying badly elsewhere.
+	v := reflect.ValueOf(f)
+
+	c.addAction(func(args []interface{}) []interface{} {
+		vargs := make([]reflect.Value, len(args))
+		ft := v.Type()
+		for i := 0; i < len(args); i++ {
+			if args[i] != nil {
+				vargs[i] = reflect.ValueOf(args[i])
+			} else {
+				// Use the zero value for the arg.
+				vargs[i] = reflect.Zero(ft.In(i))
+			}
+		}
+		v.Call(vargs)
+		return nil
+	})
+	return c
+}
+
+// Return declares the values to be returned by the mocked function call.
+func (c *Call) Return(rets ...interface{}) *Call {
+	c.t.Helper()
+
+	mt := c.methodType
+	if len(rets) != mt.NumOut() {
+		c.t.Fatalf("wrong number of arguments to Return for %T.%v: got %d, want %d [%s]",
+			c.receiver, c.method, len(rets), mt.NumOut(), c.origin)
+	}
+	for i, ret := range rets {
+		if got, want := reflect.TypeOf(ret), mt.Out(i); got == want {
+			// Identical types; nothing to do.
+		} else if got == nil {
+			// Nil needs special handling.
+			switch want.Kind() {
+			case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+				// ok
+			default:
+				c.t.Fatalf("argument %d to Return for %T.%v is nil, but %v is not nillable [%s]",
+					i, c.receiver, c.method, want, c.origin)
+			}
+		} else if got.AssignableTo(want) {
+			// Assignable type relation. Make the assignment now so that the generated code
+			// can return the values with a type assertion.
+			v := reflect.New(want).Elem()
+			v.Set(reflect.ValueOf(ret))
+			rets[i] = v.Interface()
+		} else {
+			c.t.Fatalf("wrong type of argument %d to Return for %T.%v: %v is not assignable to %v [%s]",
+				i, c.receiver, c.method, got, want, c.origin)
+		}
+	}
+
+	c.addAction(func([]interface{}) []interface{} {
+		return rets
+	})
+
+	return c
+}
+
+// Times declares the exact number of times a function call is expected to be executed.
+func (c *Call) Times(n int) *Call {
+	c.minCalls, c.maxCalls = n, n
+	return c
+}
+
+// SetArg declares an action that will set the nth argument's value,
+// indirected through a pointer. Or, in the case of a slice, SetArg
+// will copy value's elements into the nth argument.
+func (c *Call) SetArg(n int, value interface{}) *Call {
+	c.t.Helper()
+
+	mt := c.methodType
+	// TODO: This will break on variadic methods.
+	// We will need to check those at invocation time.
+	if n < 0 || n >= mt.NumIn() {
+		c.t.Fatalf("SetArg(%d, ...) called for a method with %d args [%s]",
+			n, mt.NumIn(), c.origin)
+	}
+	// Permit setting argument through an interface.
+	// In the interface case, we don't (nay, can't) check the type here.
+	at := mt.In(n)
+	switch at.Kind() {
+	case reflect.Ptr:
+		dt := at.Elem()
+		if vt := reflect.TypeOf(value); !vt.AssignableTo(dt) {
+			c.t.Fatalf("SetArg(%d, ...) argument is a %v, not assignable to %v [%s]",
+				n, vt, dt, c.origin)
+		}
+	case reflect.Interface:
+		// nothing to do
+	case reflect.Slice:
+		// nothing to do
+	default:
+		c.t.Fatalf("SetArg(%d, ...) referring to argument of non-pointer non-interface non-slice type %v [%s]",
+			n, at, c.origin)
+	}
+
+	c.addAction(func(args []interface{}) []interface{} {
+		v := reflect.ValueOf(value)
+		switch reflect.TypeOf(args[n]).Kind() {
+		case reflect.Slice:
+			setSlice(args[n], v)
+		default:
+			reflect.ValueOf(args[n]).Elem().Set(v)
+		}
+		return nil
+	})
+	return c
+}
+
+// isPreReq returns true if other is a direct or indirect prerequisite to c.
+func (c *Call) isPreReq(other *Call) bool {
+	for _, preReq := range c.preReqs {
+		if other == preReq || preReq.isPreReq(other) {
+			return true
+		}
+	}
+	return false
+}
+
+// After declares that the call may only match after preReq has been exhausted.
+func (c *Call) After(preReq *Call) *Call {
+	c.t.Helper()
+
+	if c == preReq {
+		c.t.Fatalf("A call isn't allowed to be its own prerequisite")
+	}
+	if preReq.isPreReq(c) {
+		c.t.Fatalf("Loop in call order: %v is a prerequisite to %v (possibly indirectly).", c, preReq)
+	}
+
+	c.preReqs = append(c.preReqs, preReq)
+	return c
+}
+
+// Returns true if the minimum number of calls have been made.
+func (c *Call) satisfied() bool {
+	return c.numCalls >= c.minCalls
+}
+
+// Returns true if the maximum number of calls have been made.
+func (c *Call) exhausted() bool {
+	return c.numCalls >= c.maxCalls
+}
+
+func (c *Call) String() string {
+	args := make([]string, len(c.args))
+	for i, arg := range c.args {
+		args[i] = arg.String()
+	}
+	arguments := strings.Join(args, ", ")
+	return fmt.Sprintf("%T.%v(%s) %s", c.receiver, c.method, arguments, c.origin)
+}
+
+// Tests if the given call matches the expected call.
+// If yes, returns nil. If no, returns error with message explaining why it does not match.
+func (c *Call) matches(args []interface{}) error {
+	if !c.methodType.IsVariadic() {
+		if len(args) != len(c.args) {
+			return fmt.Errorf("expected call at %s has the wrong number of arguments. Got: %d, want: %d",
+				c.origin, len(args), len(c.args))
+		}
+
+		for i, m := range c.args {
+			if !m.Matches(args[i]) {
+				got := fmt.Sprintf("%v", args[i])
+				if gs, ok := m.(GotFormatter); ok {
+					got = gs.Got(args[i])
+				}
+
+				return fmt.Errorf(
+					"expected call at %s doesn't match the argument at index %d.\nGot: %v\nWant: %v",
+					c.origin, i, got, m,
+				)
+			}
+		}
+	} else {
+		if len(c.args) < c.methodType.NumIn()-1 {
+			return fmt.Errorf("expected call at %s has the wrong number of matchers. Got: %d, want: %d",
+				c.origin, len(c.args), c.methodType.NumIn()-1)
+		}
+		if len(c.args) != c.methodType.NumIn() && len(args) != len(c.args) {
+			return fmt.Errorf("expected call at %s has the wrong number of arguments. Got: %d, want: %d",
+				c.origin, len(args), len(c.args))
+		}
+		if len(args) < len(c.args)-1 {
+			return fmt.Errorf("expected call at %s has the wrong number of arguments. Got: %d, want: greater than or equal to %d",
+				c.origin, len(args), len(c.args)-1)
+		}
+
+		for i, m := range c.args {
+			if i < c.methodType.NumIn()-1 {
+				// Non-variadic args
+				if !m.Matches(args[i]) {
+					return fmt.Errorf("expected call at %s doesn't match the argument at index %s.\nGot: %v\nWant: %v",
+						c.origin, strconv.Itoa(i), args[i], m)
+				}
+				continue
+			}
+			// The last arg has a possibility of a variadic argument, so let it branch
+
+			// sample: Foo(a int, b int, c ...int)
+			if i < len(c.args) && i < len(args) {
+				if m.Matches(args[i]) {
+					// Got Foo(a, b, c) want Foo(matcherA, matcherB, gomock.Any())
+					// Got Foo(a, b, c) want Foo(matcherA, matcherB, someSliceMatcher)
+					// Got Foo(a, b, c) want Foo(matcherA, matcherB, matcherC)
+					// Got Foo(a, b) want Foo(matcherA, matcherB)
+					// Got Foo(a, b, c, d) want Foo(matcherA, matcherB, matcherC, matcherD)
+					continue
+				}
+			}
+
+			// The number of actual args don't match the number of matchers,
+			// or the last matcher is a slice and the last arg is not.
+			// If this function still matches it is because the last matcher
+			// matches all the remaining arguments or the lack of any.
+			// Convert the remaining arguments, if any, into a slice of the
+			// expected type.
+			vargsType := c.methodType.In(c.methodType.NumIn() - 1)
+			vargs := reflect.MakeSlice(vargsType, 0, len(args)-i)
+			for _, arg := range args[i:] {
+				vargs = reflect.Append(vargs, reflect.ValueOf(arg))
+			}
+			if m.Matches(vargs.Interface()) {
+				// Got Foo(a, b, c, d, e) want Foo(matcherA, matcherB, gomock.Any())
+				// Got Foo(a, b, c, d, e) want Foo(matcherA, matcherB, someSliceMatcher)
+				// Got Foo(a, b) want Foo(matcherA, matcherB, gomock.Any())
+				// Got Foo(a, b) want Foo(matcherA, matcherB, someEmptySliceMatcher)
+				break
+			}
+			// Wrong number of matchers or not match. Fail.
+			// Got Foo(a, b) want Foo(matcherA, matcherB, matcherC, matcherD)
+			// Got Foo(a, b, c) want Foo(matcherA, matcherB, matcherC, matcherD)
+			// Got Foo(a, b, c, d) want Foo(matcherA, matcherB, matcherC, matcherD, matcherE)
+			// Got Foo(a, b, c, d, e) want Foo(matcherA, matcherB, matcherC, matcherD)
+			// Got Foo(a, b, c) want Foo(matcherA, matcherB)
+			return fmt.Errorf("Expected call at %s doesn't match the argument at index %s.\nGot: %v\nWant: %v",
+				c.origin, strconv.Itoa(i), args[i:], c.args[i])
+
+		}
+	}
+
+	// Check that all prerequisite calls have been satisfied.
+	for _, preReqCall := range c.preReqs {
+		if !preReqCall.satisfied() {
+			return fmt.Errorf("Expected call at %s doesn't have a prerequisite call satisfied:\n%v\nshould be called before:\n%v",
+				c.origin, preReqCall, c)
+		}
+	}
+
+	// Check that the call is not exhausted.
+	if c.exhausted() {
+		return fmt.Errorf("expected call at %s has already been called the max number of times", c.origin)
+	}
+
+	return nil
+}
+
+// dropPrereqs tells the expected Call to not re-check prerequisite calls any
+// longer, and to return its current set.
+func (c *Call) dropPrereqs() (preReqs []*Call) {
+	preReqs = c.preReqs
+	c.preReqs = nil
+	return
+}
+
+func (c *Call) call() []func([]interface{}) []interface{} {
+	c.numCalls++
+	return c.actions
+}
+
+// InOrder declares that the given calls should occur in order.
+func InOrder(calls ...*Call) {
+	for i := 1; i < len(calls); i++ {
+		calls[i].After(calls[i-1])
+	}
+}
+
+func setSlice(arg interface{}, v reflect.Value) {
+	va := reflect.ValueOf(arg)
+	for i := 0; i < v.Len(); i++ {
+		va.Index(i).Set(v.Index(i))
+	}
+}
+
+func (c *Call) addAction(action func([]interface{}) []interface{}) {
+	c.actions = append(c.actions, action)
+}
diff --git a/vendor/github.com/golang/mock/gomock/callset.go b/vendor/github.com/golang/mock/gomock/callset.go
new file mode 100644
index 0000000..b046b52
--- /dev/null
+++ b/vendor/github.com/golang/mock/gomock/callset.go
@@ -0,0 +1,108 @@
+// Copyright 2011 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 (
+	"bytes"
+	"fmt"
+)
+
+// callSet represents a set of expected calls, indexed by receiver and method
+// name.
+type callSet struct {
+	// Calls that are still expected.
+	expected map[callSetKey][]*Call
+	// Calls that have been exhausted.
+	exhausted map[callSetKey][]*Call
+}
+
+// callSetKey is the key in the maps in callSet
+type callSetKey struct {
+	receiver interface{}
+	fname    string
+}
+
+func newCallSet() *callSet {
+	return &callSet{make(map[callSetKey][]*Call), make(map[callSetKey][]*Call)}
+}
+
+// Add adds a new expected call.
+func (cs callSet) Add(call *Call) {
+	key := callSetKey{call.receiver, call.method}
+	m := cs.expected
+	if call.exhausted() {
+		m = cs.exhausted
+	}
+	m[key] = append(m[key], call)
+}
+
+// Remove removes an expected call.
+func (cs callSet) Remove(call *Call) {
+	key := callSetKey{call.receiver, call.method}
+	calls := cs.expected[key]
+	for i, c := range calls {
+		if c == call {
+			// maintain order for remaining calls
+			cs.expected[key] = append(calls[:i], calls[i+1:]...)
+			cs.exhausted[key] = append(cs.exhausted[key], call)
+			break
+		}
+	}
+}
+
+// FindMatch searches for a matching call. Returns error with explanation message if no call matched.
+func (cs callSet) FindMatch(receiver interface{}, method string, args []interface{}) (*Call, error) {
+	key := callSetKey{receiver, method}
+
+	// Search through the expected calls.
+	expected := cs.expected[key]
+	var callsErrors bytes.Buffer
+	for _, call := range expected {
+		err := call.matches(args)
+		if err != nil {
+			_, _ = fmt.Fprintf(&callsErrors, "\n%v", err)
+		} else {
+			return call, nil
+		}
+	}
+
+	// If we haven't found a match then search through the exhausted calls so we
+	// get useful error messages.
+	exhausted := cs.exhausted[key]
+	for _, call := range exhausted {
+		if err := call.matches(args); err != nil {
+			_, _ = fmt.Fprintf(&callsErrors, "\n%v", err)
+		}
+	}
+
+	if len(expected)+len(exhausted) == 0 {
+		_, _ = fmt.Fprintf(&callsErrors, "there are no expected calls of the method %q for that receiver", method)
+	}
+
+	return nil, fmt.Errorf(callsErrors.String())
+}
+
+// Failures returns the calls that are not satisfied.
+func (cs callSet) Failures() []*Call {
+	failures := make([]*Call, 0, len(cs.expected))
+	for _, calls := range cs.expected {
+		for _, call := range calls {
+			if !call.satisfied() {
+				failures = append(failures, call)
+			}
+		}
+	}
+	return failures
+}
diff --git a/vendor/github.com/golang/mock/gomock/controller.go b/vendor/github.com/golang/mock/gomock/controller.go
new file mode 100644
index 0000000..d7c3c65
--- /dev/null
+++ b/vendor/github.com/golang/mock/gomock/controller.go
@@ -0,0 +1,264 @@
+// 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 is a mock framework for Go.
+//
+// Standard usage:
+//   (1) Define an interface that you wish to mock.
+//         type MyInterface interface {
+//           SomeMethod(x int64, y string)
+//         }
+//   (2) Use mockgen to generate a mock from the interface.
+//   (3) Use the mock in a test:
+//         func TestMyThing(t *testing.T) {
+//           mockCtrl := gomock.NewController(t)
+//           defer mockCtrl.Finish()
+//
+//           mockObj := something.NewMockMyInterface(mockCtrl)
+//           mockObj.EXPECT().SomeMethod(4, "blah")
+//           // pass mockObj to a real object and play with it.
+//         }
+//
+// By default, expected calls are not enforced to run in any particular order.
+// Call order dependency can be enforced by use of InOrder and/or Call.After.
+// Call.After can create more varied call order dependencies, but InOrder is
+// often more convenient.
+//
+// The following examples create equivalent call order dependencies.
+//
+// Example of using Call.After to chain expected call order:
+//
+//     firstCall := mockObj.EXPECT().SomeMethod(1, "first")
+//     secondCall := mockObj.EXPECT().SomeMethod(2, "second").After(firstCall)
+//     mockObj.EXPECT().SomeMethod(3, "third").After(secondCall)
+//
+// Example of using InOrder to declare expected call order:
+//
+//     gomock.InOrder(
+//         mockObj.EXPECT().SomeMethod(1, "first"),
+//         mockObj.EXPECT().SomeMethod(2, "second"),
+//         mockObj.EXPECT().SomeMethod(3, "third"),
+//     )
+//
+// TODO:
+//	- Handle different argument/return types (e.g. ..., chan, map, interface).
+package gomock
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"runtime"
+	"sync"
+)
+
+// A TestReporter is something that can be used to report test failures.  It
+// is satisfied by the standard library's *testing.T.
+type TestReporter interface {
+	Errorf(format string, args ...interface{})
+	Fatalf(format string, args ...interface{})
+}
+
+// TestHelper is a TestReporter that has the Helper method.  It is satisfied
+// by the standard library's *testing.T.
+type TestHelper interface {
+	TestReporter
+	Helper()
+}
+
+// A Controller represents the top-level control of a mock ecosystem.  It
+// defines the scope and lifetime of mock objects, as well as their
+// expectations.  It is safe to call Controller's methods from multiple
+// goroutines. Each test should create a new Controller and invoke Finish via
+// defer.
+//
+//   func TestFoo(t *testing.T) {
+//     ctrl := gomock.NewController(t)
+//     defer ctrl.Finish()
+//     // ..
+//   }
+//
+//   func TestBar(t *testing.T) {
+//     t.Run("Sub-Test-1", st) {
+//       ctrl := gomock.NewController(st)
+//       defer ctrl.Finish()
+//       // ..
+//     })
+//     t.Run("Sub-Test-2", st) {
+//       ctrl := gomock.NewController(st)
+//       defer ctrl.Finish()
+//       // ..
+//     })
+//   })
+type Controller struct {
+	// T should only be called within a generated mock. It is not intended to
+	// be used in user code and may be changed in future versions. T is the
+	// TestReporter passed in when creating the Controller via NewController.
+	// If the TestReporter does not implement a TestHelper it will be wrapped
+	// with a nopTestHelper.
+	T             TestHelper
+	mu            sync.Mutex
+	expectedCalls *callSet
+	finished      bool
+}
+
+// NewController returns a new Controller. It is the preferred way to create a
+// Controller.
+func NewController(t TestReporter) *Controller {
+	h, ok := t.(TestHelper)
+	if !ok {
+		h = nopTestHelper{t}
+	}
+
+	return &Controller{
+		T:             h,
+		expectedCalls: newCallSet(),
+	}
+}
+
+type cancelReporter struct {
+	TestHelper
+	cancel func()
+}
+
+func (r *cancelReporter) Errorf(format string, args ...interface{}) {
+	r.TestHelper.Errorf(format, args...)
+}
+func (r *cancelReporter) Fatalf(format string, args ...interface{}) {
+	defer r.cancel()
+	r.TestHelper.Fatalf(format, args...)
+}
+
+// WithContext returns a new Controller and a Context, which is cancelled on any
+// fatal failure.
+func WithContext(ctx context.Context, t TestReporter) (*Controller, context.Context) {
+	h, ok := t.(TestHelper)
+	if !ok {
+		h = nopTestHelper{t}
+	}
+
+	ctx, cancel := context.WithCancel(ctx)
+	return NewController(&cancelReporter{h, cancel}), ctx
+}
+
+type nopTestHelper struct {
+	TestReporter
+}
+
+func (h nopTestHelper) Helper() {}
+
+// RecordCall is called by a mock. It should not be called by user code.
+func (ctrl *Controller) RecordCall(receiver interface{}, method string, args ...interface{}) *Call {
+	ctrl.T.Helper()
+
+	recv := reflect.ValueOf(receiver)
+	for i := 0; i < recv.Type().NumMethod(); i++ {
+		if recv.Type().Method(i).Name == method {
+			return ctrl.RecordCallWithMethodType(receiver, method, recv.Method(i).Type(), args...)
+		}
+	}
+	ctrl.T.Fatalf("gomock: failed finding method %s on %T", method, receiver)
+	panic("unreachable")
+}
+
+// RecordCallWithMethodType is called by a mock. It should not be called by user code.
+func (ctrl *Controller) RecordCallWithMethodType(receiver interface{}, method string, methodType reflect.Type, args ...interface{}) *Call {
+	ctrl.T.Helper()
+
+	call := newCall(ctrl.T, receiver, method, methodType, args...)
+
+	ctrl.mu.Lock()
+	defer ctrl.mu.Unlock()
+	ctrl.expectedCalls.Add(call)
+
+	return call
+}
+
+// Call is called by a mock. It should not be called by user code.
+func (ctrl *Controller) Call(receiver interface{}, method string, args ...interface{}) []interface{} {
+	ctrl.T.Helper()
+
+	// Nest this code so we can use defer to make sure the lock is released.
+	actions := func() []func([]interface{}) []interface{} {
+		ctrl.T.Helper()
+		ctrl.mu.Lock()
+		defer ctrl.mu.Unlock()
+
+		expected, err := ctrl.expectedCalls.FindMatch(receiver, method, args)
+		if err != nil {
+			origin := callerInfo(2)
+			ctrl.T.Fatalf("Unexpected call to %T.%v(%v) at %s because: %s", receiver, method, args, origin, err)
+		}
+
+		// Two things happen here:
+		// * the matching call no longer needs to check prerequite calls,
+		// * and the prerequite calls are no longer expected, so remove them.
+		preReqCalls := expected.dropPrereqs()
+		for _, preReqCall := range preReqCalls {
+			ctrl.expectedCalls.Remove(preReqCall)
+		}
+
+		actions := expected.call()
+		if expected.exhausted() {
+			ctrl.expectedCalls.Remove(expected)
+		}
+		return actions
+	}()
+
+	var rets []interface{}
+	for _, action := range actions {
+		if r := action(args); r != nil {
+			rets = r
+		}
+	}
+
+	return rets
+}
+
+// Finish checks to see if all the methods that were expected to be called
+// were called. It should be invoked for each Controller. It is not idempotent
+// and therefore can only be invoked once.
+func (ctrl *Controller) Finish() {
+	ctrl.T.Helper()
+
+	ctrl.mu.Lock()
+	defer ctrl.mu.Unlock()
+
+	if ctrl.finished {
+		ctrl.T.Fatalf("Controller.Finish was called more than once. It has to be called exactly once.")
+	}
+	ctrl.finished = true
+
+	// If we're currently panicking, probably because this is a deferred call,
+	// pass through the panic.
+	if err := recover(); err != nil {
+		panic(err)
+	}
+
+	// Check that all remaining expected calls are satisfied.
+	failures := ctrl.expectedCalls.Failures()
+	for _, call := range failures {
+		ctrl.T.Errorf("missing call(s) to %v", call)
+	}
+	if len(failures) != 0 {
+		ctrl.T.Fatalf("aborting test due to missing call(s)")
+	}
+}
+
+func callerInfo(skip int) string {
+	if _, file, line, ok := runtime.Caller(skip + 1); ok {
+		return fmt.Sprintf("%s:%d", file, line)
+	}
+	return "unknown file"
+}
diff --git a/vendor/github.com/golang/mock/gomock/matchers.go b/vendor/github.com/golang/mock/gomock/matchers.go
new file mode 100644
index 0000000..7bfc07b
--- /dev/null
+++ b/vendor/github.com/golang/mock/gomock/matchers.go
@@ -0,0 +1,255 @@
+// 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 {
+	return reflect.DeepEqual(e.x, x)
+}
+
+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)).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)}
+}