Update MD041/first-line-heading to add an allow_preamble parameter (fixes #1416).

test/first-line-heading-allow-preamble-false.md

@@ -0,0 +1,22 @@
+Text {MD041}
+
+<!-- Comment -->
+
+Text
+
+<p>HTML</p>
+
+Text
+
+- List item
+
+# Heading
+
+Text
+
+<!-- markdownlint-configure-file {
+  "first-line-heading": {
+    "allow_preamble": false
+  },
+  "no-inline-html": false
+} -->

test/first-line-heading-allow-preamble-h1.md

@@ -0,0 +1,22 @@
+Text
+
+<!-- Comment -->
+
+Text
+
+<p>HTML</p>
+
+Text
+
+- List item
+
+<h1>Heading</h1>
+
+Text
+
+<!-- markdownlint-configure-file {
+  "first-line-heading": {
+    "allow_preamble": true
+  },
+  "no-inline-html": false
+} -->

test/first-line-heading-allow-preamble-violation.md

@@ -0,0 +1,22 @@
+Text
+
+<!-- Comment -->
+
+Text
+
+<p>HTML</p>
+
+Text
+
+- List item
+
+## Heading {MD041}
+
+Text
+
+<!-- markdownlint-configure-file {
+  "first-line-heading": {
+    "allow_preamble": true
+  },
+  "no-inline-html": false
+} -->

test/first-line-heading-allow-preamble.md

@@ -0,0 +1,22 @@
+Text
+
+<!-- Comment -->
+
+Text
+
+<p>HTML</p>
+
+Text
+
+- List item
+
+# Heading
+
+Text
+
+<!-- markdownlint-configure-file {
+  "first-line-heading": {
+    "allow_preamble": true
+  },
+  "no-inline-html": false
+} -->

test/markdownlint-test.mjs

@@ -907,7 +907,7 @@ test("readme", async(t) => {
 });
 
 test("validateJsonUsingConfigSchemaStrict", async(t) => {
-  t.plan(192);
+  t.plan(196);
   // @ts-ignore
   const ajv = new Ajv(ajvOptions);
   const validateSchemaStrict = ajv.compile(configSchemaStrict);

test/snapshots/markdownlint-test-scenarios.mjs.md

@@ -13752,6 +13752,160 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## first-line-heading-allow-preamble-false.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: 'Text {MD041}',
+          errorDetail: null,
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 1,
+          ruleDescription: 'First line in a file should be a top-level heading',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md041.md',
+          ruleNames: [
+            'MD041',
+            'first-line-heading',
+            'first-line-h1',
+          ],
+        },
+      ],
+      fixed: `Text {MD041}␊
+      ␊
+      <!-- Comment -->␊
+      ␊
+      Text␊
+      ␊
+      <p>HTML</p>␊
+      ␊
+      Text␊
+      ␊
+      - List item␊
+      ␊
+      # Heading␊
+      ␊
+      Text␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "first-line-heading": {␊
+          "allow_preamble": false␊
+        },␊
+        "no-inline-html": false␊
+      } -->␊
+      `,
+    }
+
+## first-line-heading-allow-preamble-h1.md
+
+> Snapshot 1
+
+    {
+      errors: [],
+      fixed: `Text␊
+      ␊
+      <!-- Comment -->␊
+      ␊
+      Text␊
+      ␊
+      <p>HTML</p>␊
+      ␊
+      Text␊
+      ␊
+      - List item␊
+      ␊
+      <h1>Heading</h1>␊
+      ␊
+      Text␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "first-line-heading": {␊
+          "allow_preamble": true␊
+        },␊
+        "no-inline-html": false␊
+      } -->␊
+      `,
+    }
+
+## first-line-heading-allow-preamble-violation.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: '## Heading {MD041}',
+          errorDetail: null,
+          errorRange: null,
+          fixInfo: null,
+          lineNumber: 13,
+          ruleDescription: 'First line in a file should be a top-level heading',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md041.md',
+          ruleNames: [
+            'MD041',
+            'first-line-heading',
+            'first-line-h1',
+          ],
+        },
+      ],
+      fixed: `Text␊
+      ␊
+      <!-- Comment -->␊
+      ␊
+      Text␊
+      ␊
+      <p>HTML</p>␊
+      ␊
+      Text␊
+      ␊
+      - List item␊
+      ␊
+      ## Heading {MD041}␊
+      ␊
+      Text␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "first-line-heading": {␊
+          "allow_preamble": true␊
+        },␊
+        "no-inline-html": false␊
+      } -->␊
+      `,
+    }
+
+## first-line-heading-allow-preamble.md
+
+> Snapshot 1
+
+    {
+      errors: [],
+      fixed: `Text␊
+      ␊
+      <!-- Comment -->␊
+      ␊
+      Text␊
+      ␊
+      <p>HTML</p>␊
+      ␊
+      Text␊
+      ␊
+      - List item␊
+      ␊
+      # Heading␊
+      ␊
+      Text␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "first-line-heading": {␊
+          "allow_preamble": true␊
+        },␊
+        "no-inline-html": false␊
+      } -->␊
+      `,
+    }
+
 ## first_heading_bad_atx.md
 
 > Snapshot 1