Update MD051/link-fragments to add ignore_case parameter and improve documentation (fixes #1274).

test/link-fragments-default-case.md

@@ -0,0 +1,23 @@
+# Link Fragments Default Case
+
+## Heading Name
+
+[Valid](#heading-name)
+
+[Invalid](#Heading-Name) {MD051}
+
+## Valid *Heading* With _Emphasis_
+
+[Valid](#valid-heading-with-emphasis)
+
+[Invalid](#Valid-Heading-With-Emphasis) {MD051}
+
+## 🚀 Valid Heading With Emoji
+
+[Valid](#-valid-heading-with-emoji)
+
+[Invalid](#-Valid-Heading-With-Emoji) {MD051}
+
+<!-- markdownlint-configure-file {
+  "emphasis-style": false
+} -->

test/link-fragments-ignore-case.md

@@ -0,0 +1,26 @@
+# Link Fragments Ignore Case
+
+## Heading Name
+
+[Valid](#heading-name)
+
+[Valid](#Heading-Name)
+
+## Valid *Heading* With _Emphasis_
+
+[Valid](#valid-heading-with-emphasis)
+
+[Valid](#Valid-Heading-With-Emphasis)
+
+## 🚀 Valid Heading With Emoji
+
+[Valid](#-valid-heading-with-emoji)
+
+[Valid](#-Valid-Heading-With-Emoji)
+
+<!-- markdownlint-configure-file {
+  "emphasis-style": false,
+  "link-fragments": {
+    "ignore_case": true
+  }
+} -->

test/markdownlint-test.js

@@ -941,7 +941,7 @@ test("readme", async(t) => {
 });
 
 test("validateJsonUsingConfigSchemaStrict", async(t) => {
-  t.plan(179);
+  t.plan(181);
   // @ts-ignore
   const ajv = new Ajv(ajvOptions);
   const validateSchemaStrict = ajv.compile(configSchemaStrict);

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

@@ -24546,6 +24546,134 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## link-fragments-default-case.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: '[Invalid](#Heading-Name)',
+          errorDetail: 'Expected: #heading-name; Actual: #Heading-Name',
+          errorRange: [
+            1,
+            24,
+          ],
+          fixInfo: {
+            deleteCount: 13,
+            editColumn: 11,
+            insertText: '#heading-name',
+          },
+          lineNumber: 7,
+          ruleDescription: 'Link fragments should be valid',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md051.md',
+          ruleNames: [
+            'MD051',
+            'link-fragments',
+          ],
+        },
+        {
+          errorContext: '[Invalid](#Valid-Heading-With-Emphasis)',
+          errorDetail: 'Expected: #valid-heading-with-emphasis; Actual: #Valid-Heading-With-Emphasis',
+          errorRange: [
+            1,
+            39,
+          ],
+          fixInfo: {
+            deleteCount: 28,
+            editColumn: 11,
+            insertText: '#valid-heading-with-emphasis',
+          },
+          lineNumber: 13,
+          ruleDescription: 'Link fragments should be valid',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md051.md',
+          ruleNames: [
+            'MD051',
+            'link-fragments',
+          ],
+        },
+        {
+          errorContext: '[Invalid](#-Valid-Heading-With-Emoji)',
+          errorDetail: 'Expected: #-valid-heading-with-emoji; Actual: #-Valid-Heading-With-Emoji',
+          errorRange: [
+            1,
+            37,
+          ],
+          fixInfo: {
+            deleteCount: 26,
+            editColumn: 11,
+            insertText: '#-valid-heading-with-emoji',
+          },
+          lineNumber: 19,
+          ruleDescription: 'Link fragments should be valid',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md051.md',
+          ruleNames: [
+            'MD051',
+            'link-fragments',
+          ],
+        },
+      ],
+      fixed: `# Link Fragments Default Case␊
+      ␊
+      ## Heading Name␊
+      ␊
+      [Valid](#heading-name)␊
+      ␊
+      [Invalid](#heading-name) {MD051}␊
+      ␊
+      ## Valid *Heading* With _Emphasis_␊
+      ␊
+      [Valid](#valid-heading-with-emphasis)␊
+      ␊
+      [Invalid](#valid-heading-with-emphasis) {MD051}␊
+      ␊
+      ## 🚀 Valid Heading With Emoji␊
+      ␊
+      [Valid](#-valid-heading-with-emoji)␊
+      ␊
+      [Invalid](#-valid-heading-with-emoji) {MD051}␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "emphasis-style": false␊
+      } -->␊
+      `,
+    }
+
+## link-fragments-ignore-case.md
+
+> Snapshot 1
+
+    {
+      errors: [],
+      fixed: `# Link Fragments Ignore Case␊
+      ␊
+      ## Heading Name␊
+      ␊
+      [Valid](#heading-name)␊
+      ␊
+      [Valid](#Heading-Name)␊
+      ␊
+      ## Valid *Heading* With _Emphasis_␊
+      ␊
+      [Valid](#valid-heading-with-emphasis)␊
+      ␊
+      [Valid](#Valid-Heading-With-Emphasis)␊
+      ␊
+      ## 🚀 Valid Heading With Emoji␊
+      ␊
+      [Valid](#-valid-heading-with-emoji)␊
+      ␊
+      [Valid](#-Valid-Heading-With-Emoji)␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "emphasis-style": false,␊
+        "link-fragments": {␊
+          "ignore_case": true␊
+        }␊
+      } -->␊
+      `,
+    }
+
 ## link-fragments.md
 
 > Snapshot 1