Added terrors.Verbose()

errors.go

@@ -63,12 +63,26 @@ type Error struct {
 	// should not expect it to contain information about terrors from other downstream
 	// processes.
 	cause error
+
+	// verbose is a flag that will cause Error() to return the VerboseString() rather
+	// than the conventional short message. This is intended for ease of debugging,
+	// especially in tests, rather than regular use.
+	verbose bool
 }
 
 // Error returns a string message of the error.
 // It will contain the code and error message. If there is a causal chain, the
-// message from each error in the chain will be added to the output.
+// message from each error in the chain will be added to the output. If the
+// Error is marked as "verbose", it will also return the Params and stack trace.
 func (p *Error) Error() string {
+	if p.verbose {
+		return p.VerboseString()
+	}
+	return p.ShortString()
+}
+
+// ShortString returns the conventional error description usually returned by Error()
+func (p *Error) ShortString() string {
 	if p.cause == nil {
 		// Not sure if the empty code/message cases actually happen, but to be safe, defer to
 		// the 'old' error message if there is no cause present (i.e. we're not using
@@ -131,7 +145,7 @@ func (p *Error) StackString() string {
 
 // VerboseString returns the error message, stack trace and params
 func (p *Error) VerboseString() string {
-	return fmt.Sprintf("%s\nParams: %+v\n%s", p.Error(), p.Params, p.StackString())
+	return fmt.Sprintf("%s\nParams: %+v\n%s", p.ShortString(), p.Params, p.StackString())
 }
 
 // Retryable determines whether the error was caused by an action which can be retried.
@@ -333,3 +347,30 @@ func Is(err error, code ...string) bool {
 		return false
 	}
 }
+
+// Verbose returns a shallow copy of the given terrors.Error that returns a "verbose" message for error.Error
+// instead of the usual short version. If passed nil or another underlying error type, it will return it
+// unchanged. This is useful for instance in tests where you may want to write
+//
+//   require.NoError(t, terrors.Verbose(err))
+//
+func Verbose(err error) error {
+	if err == nil {
+		return nil
+	}
+	switch err := err.(type) {
+	case *Error:
+		return &Error{
+			verbose: true,
+
+			Code:        err.Code,
+			Message:     err.Message,
+			Params:      err.Params,
+			StackFrames: err.StackFrames,
+			IsRetryable: err.IsRetryable,
+			cause:       err.cause,
+		}
+	default:
+		return err
+	}
+}

errors_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/monzo/terrors/stack"
 )
@@ -481,3 +482,37 @@ func TestRetryable(t *testing.T) {
 		})
 	}
 }
+
+func TestVerbose(t *testing.T) {
+	var err, verboseErr error
+	var terr, verboseTerr *Error
+
+	assert.Nil(t, err)
+	assert.Nil(t, Verbose(err))
+
+	err = errors.New("blah")
+	assert.Same(t, err, Verbose(err))
+
+	err = New("test", "Test", map[string]string{"flavour": "banana"})
+	require.NotNil(t, err)
+
+	verboseErr = Verbose(err)
+
+	terr = err.(*Error)
+	require.NotNil(t, terr)
+
+	verboseTerr = verboseErr.(*Error)
+	require.NotNil(t, verboseTerr)
+
+	assert.Equal(t, err.Error(), terr.ShortString())
+
+	assert.NotSame(t, err, verboseErr)
+	assert.NotSame(t, terr, verboseTerr)
+	assert.Equal(t, verboseErr.Error(), terr.VerboseString())
+	assert.Equal(t, verboseErr.Error(), verboseTerr.VerboseString())
+
+	// the errors should be equal except for the verbose flag
+	verboseTerr.verbose = false
+	assert.Equal(t, terr, verboseTerr)
+
+}

go.mod

@@ -4,7 +4,7 @@ go 1.17
 
 require (
 	github.com/golang/protobuf v1.4.2
-	github.com/stretchr/testify v1.6.1
+	github.com/stretchr/testify v1.7.0
 )
 
 require (

go.sum

@@ -29,8 +29,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
-github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=