resources/page: Implement compare.ProbablyEqer for the core slices

Fixes #5808

resources/page/pages_test.go

@@ -0,0 +1,55 @@
+// Copyright 2019 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 page
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestProbablyEq(t *testing.T) {
+
+	p1, p2, p3 := &testPage{title: "p1"}, &testPage{title: "p2"}, &testPage{title: "p3"}
+	pages12 := Pages{p1, p2}
+	pages21 := Pages{p2, p1}
+	pages123 := Pages{p1, p2, p3}
+
+	t.Run("Pages", func(t *testing.T) {
+		assert := require.New(t)
+
+		assert.True(pages12.ProbablyEq(pages12))
+		assert.False(pages123.ProbablyEq(pages12))
+		assert.False(pages12.ProbablyEq(pages21))
+	})
+
+	t.Run("PageGroup", func(t *testing.T) {
+		assert := require.New(t)
+
+		assert.True(PageGroup{Key: "a", Pages: pages12}.ProbablyEq(PageGroup{Key: "a", Pages: pages12}))
+		assert.False(PageGroup{Key: "a", Pages: pages12}.ProbablyEq(PageGroup{Key: "b", Pages: pages12}))
+
+	})
+
+	t.Run("PagesGroup", func(t *testing.T) {
+		assert := require.New(t)
+
+		pg1, pg2 := PageGroup{Key: "a", Pages: pages12}, PageGroup{Key: "b", Pages: pages123}
+
+		assert.True(PagesGroup{pg1, pg2}.ProbablyEq(PagesGroup{pg1, pg2}))
+		assert.False(PagesGroup{pg1, pg2}.ProbablyEq(PagesGroup{pg2, pg1}))
+
+	})
+
+}