add GetStack and tests to stackerr pkg

cmd/mockery.go

@@ -91,15 +91,11 @@ func NewRootCmd() *cobra.Command {
 	return cmd
 }
 
-type stacker interface {
-	Stack() []byte
-}
-
 func printStackTrace(e error) {
 	fmt.Printf("%v\n", e)
-	var s stacker
-	if errors.As(e, &s) {
-		fmt.Printf("%+s\n", s.Stack())
+
+	if stack, ok := stackerr.GetStack(e); ok {
+		fmt.Printf("%+s\n", stack)
 	}
 }
 

pkg/stackerr/stackerr.go

@@ -1,6 +1,7 @@
 package stackerr
 
 import (
+	"errors"
 	"fmt"
 	"runtime/debug"
 )
@@ -34,3 +35,13 @@ func (se StackErr) Unwrap() error {
 func (se StackErr) Stack() []byte {
 	return se.stack
 }
+
+func GetStack(err error) ([]byte, bool) {
+	var s interface {
+		Stack() []byte
+	}
+	if errors.As(err, &s) {
+		return s.Stack(), true
+	}
+	return nil, false
+}

pkg/stackerr/stackerr_test.go

@@ -0,0 +1,43 @@
+package stackerr
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStackErr(t *testing.T) {
+	err := assert.AnError
+
+	s, ok := GetStack(err)
+	assert.False(t, ok)
+	assert.Empty(t, s)
+
+	err = NewStackErr(err)
+	assert.Equal(t, assert.AnError.Error(), err.Error())
+
+	s, ok = GetStack(err)
+	assert.True(t, ok)
+	assert.NotEmpty(t, s)
+
+	err = NewStackErr(fmt.Errorf("wrapped error can still get stack: %w", err))
+	s, ok = GetStack(err)
+	assert.True(t, ok)
+	assert.NotEmpty(t, s)
+}
+
+func TestStackErrf(t *testing.T) {
+	err := assert.AnError
+
+	s, ok := GetStack(err)
+	assert.False(t, ok)
+	assert.Empty(t, s)
+
+	err = NewStackErrf(err, "error message %d %s", 1, "a")
+	assert.Equal(t, "error message 1 a: "+assert.AnError.Error(), err.Error())
+
+	s, ok = GetStack(err)
+	assert.True(t, ok)
+	assert.NotEmpty(t, s)
+}