chore: import upstream snapshot with attribution

errs/problem_test.go

@@ -0,0 +1,72 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package errs
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestProblemError(t *testing.T) {
+	tests := []struct {
+		name string
+		p    Problem
+		want string
+	}{
+		{"empty message", Problem{}, ""},
+		{"plain message", Problem{Message: "boom"}, "boom"},
+		{"message ignores hint", Problem{Message: "msg", Hint: "do x"}, "msg"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := (&tt.p).Error(); got != tt.want {
+				t.Errorf("Error() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+// TestProblemError_NilReceiverDoesNotPanic pins the nil-receiver guard on
+// (*Problem).Error(). Without it, a nil *Problem stored in an error interface
+// would panic when the root dispatcher calls err.Error() for logging.
+func TestProblemError_NilReceiverDoesNotPanic(t *testing.T) {
+	var p *Problem // nil
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("(*Problem)(nil).Error() panicked: %v", r)
+		}
+	}()
+	if got := p.Error(); got != "" {
+		t.Errorf("(*Problem)(nil).Error() = %q, want \"\"", got)
+	}
+}
+
+func TestProblemDetailReturnsReceiver(t *testing.T) {
+	p := &Problem{Message: "x"}
+	if got := p.ProblemDetail(); got != p {
+		t.Errorf("ProblemDetail() = %p, want receiver %p", got, p)
+	}
+}
+
+func TestProblemHasNoComponentField(t *testing.T) {
+	if f, ok := reflect.TypeOf(Problem{}).FieldByName("Component"); ok {
+		t.Errorf("Problem.Component must not exist; got field %#v", f)
+	}
+}
+
+func TestProblemHasNoDocURLField(t *testing.T) {
+	if f, ok := reflect.TypeOf(Problem{}).FieldByName("DocURL"); ok {
+		t.Errorf("Problem.DocURL must not exist on the base Problem (PermissionError carries ConsoleURL instead); got field %#v", f)
+	}
+}
+
+func TestProblemCategoryTagIsType(t *testing.T) {
+	f, ok := reflect.TypeOf(Problem{}).FieldByName("Category")
+	if !ok {
+		t.Fatalf("Problem.Category must exist")
+	}
+	if got := f.Tag.Get("json"); got != "type" {
+		t.Errorf("Problem.Category json tag = %q, want %q", got, "type")
+	}
+}