port @layer tests from AOT to JIT mode (#5379)

tests/layer-at-rules.test.js

@@ -49,3 +49,134 @@ test('custom user-land utilities', () => {
     `)
   })
 })
+
+test('layers are grouped and inserted at the matching @tailwind rule', () => {
+  let config = {
+    content: [
+      { raw: html`<div class="input btn card float-squirrel align-banana align-sandwich"></div>` },
+    ],
+    plugins: [
+      function ({ addBase, addComponents, addUtilities }) {
+        addBase({ body: { margin: 0 } })
+
+        addComponents({
+          '.input': { background: 'white' },
+        })
+
+        addUtilities({
+          '.float-squirrel': { float: 'squirrel' },
+        })
+      },
+    ],
+    corePlugins: { preflight: false },
+  }
+
+  let input = css`
+    @layer vanilla {
+      strong {
+        font-weight: medium;
+      }
+    }
+
+    @tailwind base;
+    @tailwind components;
+    @tailwind utilities;
+
+    @layer components {
+      .btn {
+        background: blue;
+      }
+    }
+
+    @layer utilities {
+      .align-banana {
+        text-align: banana;
+      }
+    }
+
+    @layer base {
+      h1 {
+        font-weight: bold;
+      }
+    }
+
+    @layer components {
+      .card {
+        border-radius: 12px;
+      }
+    }
+
+    @layer base {
+      p {
+        font-weight: normal;
+      }
+    }
+
+    @layer utilities {
+      .align-sandwich {
+        text-align: sandwich;
+      }
+    }
+
+    @layer chocolate {
+      a {
+        text-decoration: underline;
+      }
+    }
+  `
+
+  expect.assertions(2)
+
+  return run(input, config).then((result) => {
+    expect(result.warnings().length).toBe(0)
+    expect(result.css).toMatchFormattedCss(css`
+      @layer vanilla {
+        strong {
+          font-weight: medium;
+        }
+      }
+
+      body {
+        margin: 0;
+      }
+
+      h1 {
+        font-weight: bold;
+      }
+
+      p {
+        font-weight: normal;
+      }
+
+      .input {
+        background: white;
+      }
+
+      .btn {
+        background: blue;
+      }
+
+      .card {
+        border-radius: 12px;
+      }
+
+      .float-squirrel {
+        float: squirrel;
+      }
+
+      .align-banana {
+        text-align: banana;
+      }
+
+      .align-sandwich {
+        text-align: sandwich;
+      }
+
+      @layer chocolate {
+        a {
+          text-decoration: underline;
+        }
+      }
+    `)
+  })
+})