Make cascade front matter order deterministic

Fixes #12594

common/maps/ordered_test.go

@@ -0,0 +1,99 @@
+// Copyright 2024 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package maps
+
+import (
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+)
+
+func TestOrdered(t *testing.T) {
+	c := qt.New(t)
+
+	m := NewOrdered[string, int]()
+	m.Set("a", 1)
+	m.Set("b", 2)
+	m.Set("c", 3)
+
+	c.Assert(m.Keys(), qt.DeepEquals, []string{"a", "b", "c"})
+	c.Assert(m.Values(), qt.DeepEquals, []int{1, 2, 3})
+
+	v, found := m.Get("b")
+	c.Assert(found, qt.Equals, true)
+	c.Assert(v, qt.Equals, 2)
+
+	m.Set("b", 22)
+	c.Assert(m.Keys(), qt.DeepEquals, []string{"a", "b", "c"})
+	c.Assert(m.Values(), qt.DeepEquals, []int{1, 22, 3})
+
+	m.Delete("b")
+
+	c.Assert(m.Keys(), qt.DeepEquals, []string{"a", "c"})
+	c.Assert(m.Values(), qt.DeepEquals, []int{1, 3})
+}
+
+func TestOrderedHash(t *testing.T) {
+	c := qt.New(t)
+
+	m := NewOrdered[string, int]()
+	m.Set("a", 1)
+	m.Set("b", 2)
+	m.Set("c", 3)
+
+	h1, err := m.Hash()
+	c.Assert(err, qt.IsNil)
+
+	m.Set("d", 4)
+
+	h2, err := m.Hash()
+	c.Assert(err, qt.IsNil)
+
+	c.Assert(h1, qt.Not(qt.Equals), h2)
+
+	m = NewOrdered[string, int]()
+	m.Set("b", 2)
+	m.Set("a", 1)
+	m.Set("c", 3)
+
+	h3, err := m.Hash()
+	c.Assert(err, qt.IsNil)
+	// Order does not matter.
+	c.Assert(h1, qt.Equals, h3)
+}
+
+func TestOrderedNil(t *testing.T) {
+	c := qt.New(t)
+
+	var m *Ordered[string, int]
+
+	m.Set("a", 1)
+	c.Assert(m.Keys(), qt.IsNil)
+	c.Assert(m.Values(), qt.IsNil)
+	v, found := m.Get("a")
+	c.Assert(found, qt.Equals, false)
+	c.Assert(v, qt.Equals, 0)
+	m.Delete("a")
+	var b bool
+	m.Range(func(k string, v int) bool {
+		b = true
+		return true
+	})
+	c.Assert(b, qt.Equals, false)
+	c.Assert(m.Len(), qt.Equals, 0)
+	c.Assert(m.Clone(), qt.IsNil)
+	h, err := m.Hash()
+	c.Assert(err, qt.IsNil)
+	c.Assert(h, qt.Equals, uint64(0))
+}