Gomega matchers for other error packages

This package provides Gomega matchers to write assertions against errors:

• wrapped using Dave Cheney's github.com/pkg/errors package
• included in Hashicorp's github.com/hashicorp/go-multierror package

This package is needed to address deficiencies in gomega's default MatchError()

MatchWrappedError()

Verifies that an error matches the expected one, including errors that have been wrapped by a context.

import (
  "errors"
  perrors "github.com/pkg/errors"
  
  . "github.com/chendrix/gerrors"
)

err := errors.New("some error")
err2 := perrors.Wrap(err, "read failed")

Expect(err).To(MatchError("some error")) // Pass
Expect(err2).To(MatchError("some error")) // Fail!

Expect(err).To(MatchWrappedError("some error")) // Pass
Expect(err2).To(MatchWrappedError("some error")) // Pass

ContainMatchedError()

Verifies that an error is included in a go-multierror error.

import (
  "errors"
   "github.com/hashicorp/go-multierror"
  
  . "github.com/chendrix/gerrors"
)

var result error 
err := errors.New("some error")

result = multierror.Append(result, err)

Expect(err).To(MatchError("some error")) // Pass
Expect(result).To(MatchError("some error")) // Fail!

Expect(err).To(ContainWrappedError("some error")) // Pass
Expect(result).To(ContainWrappedError("some error")) // Pass