From 4381bee03524f4276986130cc2abf7503276b57a Mon Sep 17 00:00:00 2001
From: John Behm <jxsl13@googlemail.com>
Date: Sun, 20 Aug 2023 21:45:17 +0200
Subject: [PATCH] add errorutils tests

---
 internal/errorutils/errorutils_test.go | 15 +++--
 internal/errorutils/filter_test.go     | 93 ++++++++++++++++++++++++++
 2 files changed, 103 insertions(+), 5 deletions(-)
 create mode 100644 internal/errorutils/filter_test.go

diff --git a/internal/errorutils/errorutils_test.go b/internal/errorutils/errorutils_test.go
index 6b4e87aa..7745609e 100644
--- a/internal/errorutils/errorutils_test.go
+++ b/internal/errorutils/errorutils_test.go
@@ -10,16 +10,17 @@ import (
 
 func TestUnwrapErrors(t *testing.T) {
 	err := Join(errors.New("foo"), errors.New("bar"))
+	require.NotEmpty(t, err.Error())
 
-	errs := Unwrap(err)
+	errs := ShallowUnwrap(err)
 	require.Len(t, errs, 2)
 }
 
 func TestUnwrapError(t *testing.T) {
 	err := fmt.Errorf("foo: %w", errors.New("bar"))
 
-	errs := Unwrap(err)
-	require.Len(t, errs, 2)
+	errs := ShallowUnwrap(err)
+	require.Len(t, errs, 1)
 }
 
 func TestUnwrapHierarchyError(t *testing.T) {
@@ -31,11 +32,15 @@ func TestUnwrapHierarchyError(t *testing.T) {
 
 	err := Join(Join(nil, err2), Join(nil, err4, nil))
 
-	errs := Unwrap(err)
-	require.Len(t, errs, 4)
+	errs := ShallowUnwrap(err)
+	require.Len(t, errs, 2)
 }
 
 func TestJoinNils(t *testing.T) {
 	err := Join(nil, nil)
 	require.Nil(t, err)
 }
+
+func TestDeepMultiErrorUnwrapNil(t *testing.T) {
+	require.Nil(t, deepUnwrapMultiError(nil))
+}
diff --git a/internal/errorutils/filter_test.go b/internal/errorutils/filter_test.go
new file mode 100644
index 00000000..b53b67a8
--- /dev/null
+++ b/internal/errorutils/filter_test.go
@@ -0,0 +1,93 @@
+package errorutils
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type customErr struct {
+	FieldValue string
+}
+
+func (e *customErr) Error() string {
+	return e.FieldValue
+}
+
+func shallowFilter(err error) bool {
+	_, ok := err.(*customErr)
+	return ok
+}
+
+func deepFilter(err error) bool {
+	var cerr *customErr
+	return errors.As(err, &cerr)
+}
+
+func removeAllFilter(err error) bool {
+	return false
+}
+
+func TestFilter(t *testing.T) {
+
+	errs := []error{
+		&customErr{FieldValue: "foo"},
+		fmt.Errorf("foo: %w", &customErr{FieldValue: "foo"}),
+		errors.New("bar"),
+		nil,
+	}
+
+	filtered := Filter(errs, shallowFilter)
+
+	require.Len(t, filtered, 1)
+
+	for _, err := range filtered {
+		require.NotNil(t, err)
+		cerr, ok := err.(*customErr)
+		require.True(t, ok, "cannot type assert to customErr")
+
+		require.NotEmpty(t, cerr.FieldValue)
+	}
+
+	filtered = Filter(errs, deepFilter)
+
+	require.Len(t, filtered, 2)
+}
+
+func TestFilteredNormal(t *testing.T) {
+	errs := []error{
+		&customErr{FieldValue: "foo"},
+		fmt.Errorf("foo: %w", &customErr{FieldValue: "foo"}),
+		errors.New("bar"),
+		nil,
+	}
+	err := Join(errs...)
+
+	filtered := Filtered(err, shallowFilter)
+
+	require.Len(t, ShallowUnwrap(filtered), 1)
+
+	filtered = Filtered(err, deepFilter)
+	require.Len(t, ShallowUnwrap(filtered), 2)
+}
+
+func TestFilteredNil(t *testing.T) {
+
+	filtered := Filtered(nil, shallowFilter)
+	require.Nil(t, filtered)
+}
+
+func TestFilteredEmpty(t *testing.T) {
+	errs := []error{
+		&customErr{FieldValue: "foo"},
+		fmt.Errorf("foo: %w", &customErr{FieldValue: "foo"}),
+		errors.New("bar"),
+		nil,
+	}
+	err := Join(errs...)
+
+	filtered := Filtered(err, removeAllFilter)
+	require.Len(t, ShallowUnwrap(filtered), 0)
+}