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// Copyright 2011 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// 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 oglematchers
import (
"errors"
"fmt"
"reflect"
)
// Panics matches zero-arg functions which, when invoked, panic with an error
// that matches the supplied matcher.
//
// NOTE(jacobsa): This matcher cannot detect the case where the function panics
// using panic(nil), by design of the language. See here for more info:
//
// http://goo.gl/9aIQL
//
func Panics(m Matcher) Matcher {
return &panicsMatcher{m}
}
type panicsMatcher struct {
wrappedMatcher Matcher
}
func (m *panicsMatcher) Description() string {
return "panics with: " + m.wrappedMatcher.Description()
}
func (m *panicsMatcher) Matches(c interface{}) (err error) {
// Make sure c is a zero-arg function.
v := reflect.ValueOf(c)
if v.Kind() != reflect.Func || v.Type().NumIn() != 0 {
err = NewFatalError("which is not a zero-arg function")
return
}
// Call the function and check its panic error.
defer func() {
if e := recover(); e != nil {
err = m.wrappedMatcher.Matches(e)
// Set a clearer error message if the matcher said no.
if err != nil {
wrappedClause := ""
if err.Error() != "" {
wrappedClause = ", " + err.Error()
}
err = errors.New(fmt.Sprintf("which panicked with: %v%s", e, wrappedClause))
}
}
}()
v.Call([]reflect.Value{})
// If we get here, the function didn't panic.
err = errors.New("which didn't panic")
return
}
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