IlyasYOY · November 22, 2024 15:38 · Nov 22, 2024
diff --git a/detailederror.go b/detailederror.go
@@ -0,0 +1,44 @@
+package detailederror
+
+import "errors"
+
+type detailedError struct {
+    err error
+    key string
+    val string
+}
+
+func (d *detailedError) Error() string {
+    return d.err.Error()
+}
+
+func WithDetails(err error, key, value string) error {
+    return &detailedError{
+        err: err,
+        key: key,
+        val: value,
+    }
+}
+
+func GetDetail(err error, key string) (string, bool) {
+    nextErr := err
+    var derr *detailedError
+    for errors.As(nextErr, &derr) {
+        if derr.key == key {
+            return derr.val, true
+        }
+        nextErr = derr.err
+    }
+    return "", false
+}
+
+func GetDetails(err error) map[string]string {
+    nextErr := err
+    var derr *detailedError
+    details := make(map[string]string, 0)
+    for errors.As(nextErr, &derr) {
+        details[derr.key] = derr.val
+        nextErr = derr.err
+    }
+    return details
+}
diff --git a/detailederror_test.go b/detailederror_test.go
@@ -0,0 +1,88 @@
+package detailederror_test
+
+import (
+    "errors"
+    "testing"
+
+    "github.com/IlyasYOY/detailederror"
+    "github.com/google/go-cmp/cmp"
+)
+
+func TestWithDetails(t *testing.T) {
+    err := errors.New("test")
+
+    gotErr := detailederror.WithDetails(err, "user", "ilya")
+
+    if gotErr == nil {
+        t.Errorf("error must not be nil: %v", gotErr)
+    }
+}
+
+func TestGetDetail_Nested(t *testing.T) {
+    err := errors.New("test")
+    key1 := "user1"
+    want1 := "ilya1"
+    detailedErr1 := detailederror.WithDetails(err, key1, want1)
+    key2 := "user2"
+    want2 := "ilya2"
+    detailedErr2 := detailederror.WithDetails(detailedErr1, key2, want2)
+
+    got2, ok2 := detailederror.GetDetail(detailedErr2, key2)
+    got1, ok1 := detailederror.GetDetail(detailedErr2, key1)
+
+    if !ok1 {
+        t.Fatalf("value not found by key: %q", key1)
+    }
+    if !ok2 {
+        t.Fatalf("value not found by key: %q", key2)
+    }
+    if got2 != want2 {
+        t.Errorf("value must be equal to %q", want2)
+    }
+    if got1 != want1 {
+        t.Errorf("value must be equal to %q", want1)
+    }
+}
+
+func TestGetDetails_Nested(t *testing.T) {
+    err := errors.New("test")
+    detailedErr1 := detailederror.WithDetails(err, "user1", "ilya1")
+    detailedErr2 := detailederror.WithDetails(detailedErr1, "user2", "ilya2")
+
+    got := detailederror.GetDetails(detailedErr2)
+
+    if diff := cmp.Diff(map[string]string{
+        "user1": "ilya1",
+        "user2": "ilya2",
+    }, got); diff != "" {
+        t.Errorf("(-want +got):\\n%s", diff)
+    }
+}
+
+func TestGetDetail(t *testing.T) {
+    err := errors.New("test")
+    key := "user"
+    want := "ilya"
+    detailedErr := detailederror.WithDetails(err, key, want)
+
+    got, ok := detailederror.GetDetail(detailedErr, key)
+
+    if !ok {
+        t.Fatalf("value not found by key: %q", key)
+    }
+    if got != want {
+        t.Errorf("value must be equal to %q", want)
+    }
+}
+
+func TestGetDetail_Absent(t *testing.T) {
+    err := errors.New("test")
+    want := "ilya"
+    detailedErr := detailederror.WithDetails(err, "name", want)
+
+    _, ok := detailederror.GetDetail(detailedErr, "user")
+
+    if ok {
+        t.Fatalf("value was found")
+    }
+}