Add css.TailwindCSS

Closes #12618
Closes #12620

resources/resource_transformers/cssjs/tailwindcss_integration_test.go

@@ -0,0 +1,72 @@
+// 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 cssjs_test
+
+import (
+	"testing"
+
+	"github.com/bep/logg"
+	"github.com/gohugoio/hugo/htesting"
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestTailwindV4Basic(t *testing.T) {
+	if !htesting.IsCI() {
+		t.Skip("Skip long running test when running locally")
+	}
+
+	files := `
+-- hugo.toml --
+-- package.json --
+{
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/bep/hugo-starter-tailwind-basic.git"
+  },
+  "devDependencies": {
+    "@tailwindcss/cli": "^4.0.0-alpha.16",
+    "tailwindcss": "^4.0.0-alpha.16"
+  },
+  "name": "hugo-starter-tailwind-basic",
+  "version": "0.1.0"
+}
+-- assets/css/styles.css --
+@import "tailwindcss";
+
+@theme {
+  --font-family-display: "Satoshi", "sans-serif";
+
+  --breakpoint-3xl: 1920px;
+
+  --color-neon-pink: oklch(71.7% 0.25 360);
+  --color-neon-lime: oklch(91.5% 0.258 129);
+  --color-neon-cyan: oklch(91.3% 0.139 195.8);
+}
+-- layouts/index.html --
+{{ $css := resources.Get "css/styles.css" | css.TailwindCSS }}
+CSS: {{ $css.Content | safeCSS }}|
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:               t,
+			TxtarString:     files,
+			NeedsOsFS:       true,
+			NeedsNpmInstall: true,
+			LogLevel:        logg.LevelInfo,
+		}).Build()
+
+	b.AssertFileContent("public/index.html", "/*! tailwindcss v4.0.0")
+}