Preserve front matter slice value types (e.g. int)

Fixes #10624

hugolib/frontmatter_test.go

@@ -0,0 +1,47 @@
+// Copyright 2022 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 hugolib
+
+import "testing"
+
+// Issue 10624
+func TestFrontmatterPreserveDatatypesForSlices(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- content/post/one.md --
+---
+ints: [1, 2, 3]
+mixed: ["1", 2, 3]
+strings: ["1", "2","3"]
+---	
+-- layouts/_default/single.html --
+Ints: {{ printf "%T" .Params.ints }} {{ range .Params.ints }}Int: {{ fmt.Printf "%[1]v (%[1]T)" . }}|{{ end }}
+Mixed: {{ printf "%T" .Params.mixed }} {{ range .Params.mixed }}Mixed: {{ fmt.Printf "%[1]v (%[1]T)" . }}|{{ end }}
+Strings: {{ printf "%T" .Params.strings }} {{ range .Params.strings }}Strings: {{ fmt.Printf "%[1]v (%[1]T)" . }}|{{ end }}
+`
+	b := NewIntegrationTestBuilder(
+		IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+		},
+	)
+
+	b.Build()
+
+	b.AssertFileContent("public/post/one/index.html", "Ints: []interface {} Int: 1 (int)|Int: 2 (int)|Int: 3 (int)|")
+	b.AssertFileContent("public/post/one/index.html", "Mixed: []interface {} Mixed: 1 (string)|Mixed: 2 (int)|Mixed: 3 (int)|")
+	b.AssertFileContent("public/post/one/index.html", "Strings: []string Strings: 1 (string)|Strings: 2 (string)|Strings: 3 (string)|")
+
+}