Added function to build more useful error messages for debugging.

util/error.go

@@ -1,6 +1,9 @@
 package util
 
-import "fmt"
+import (
+	"bytes"
+	"fmt"
+)
 
 /*
 Err is the implementation of error that all goadb functions return.
@@ -118,3 +121,24 @@ func HasErrCode(err error, code ErrCode) bool {
 		return false
 	}
 }
+
+/*
+ErrorWithCauseChain formats err and all its causes if it's an *Err, else returns
+err.Error().
+*/
+func ErrorWithCauseChain(err error) string {
+	var buffer bytes.Buffer
+
+	for {
+		if wrappedErr, ok := err.(*Err); ok && wrappedErr.Cause != nil {
+			fmt.Fprintln(&buffer, wrappedErr.Error())
+			fmt.Fprint(&buffer, "caused by ")
+			err = wrappedErr.Cause
+		} else {
+			break
+		}
+	}
+	buffer.WriteString(err.Error())
+
+	return buffer.String()
+}

util/error_test.go

@@ -0,0 +1,26 @@
+package util
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrorWithCauseChain(t *testing.T) {
+	err := &Err{
+		Message: "err1",
+		Code:    AssertionError,
+		Cause: &Err{
+			Message: "err2",
+			Code:    AssertionError,
+			Cause:   errors.New("err3"),
+		},
+	}
+
+	expected := `AssertionError: err1
+caused by AssertionError: err2
+caused by err3`
+
+	assert.Equal(t, expected, ErrorWithCauseChain(err))
+}