feat: support line number checking in link fragment (e.g: '#L50')

Fixes #6

test/fixtures/invalid/invalid-heading-with-L-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-heading-with-L-fragment/invalid-heading-with-L-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment line number 7](./awesome.md#L7abc)

test/fixtures/invalid/invalid-line-number-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-line-number-fragment/invalid-line-number-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment line number 7](./awesome.md#L7)

test/fixtures/valid/existing-heading-case-insensitive/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## Existing Heading

test/fixtures/valid/existing-heading-case-insensitive/existing-heading-case-insensitive.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#ExistIng-Heading)

test/fixtures/valid/existing-heading-fragment/awesome.md

@@ -1,4 +1,4 @@
-# Valid
+# Awesome
 
 ## Existing Heading
 

test/fixtures/valid/valid-heading-like-number-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## L7

test/fixtures/valid/valid-heading-like-number-fragment/valid-heading-like-number-fragment.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#L7)

test/fixtures/valid/valid-line-number-fragment/awesome.md

@@ -0,0 +1,9 @@
+# Awesome
+
+ABC
+
+Line 5
+
+Line 7 Text
+
+## L7

test/fixtures/valid/valid-line-number-fragment/valid-line-number-fragment.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment line number 7](./awesome.md#L7)

test/index.test.js

@@ -45,6 +45,19 @@ test("ensure the rule validates correctly", async (t) => {
         error:
           '"./awesome.md#not-an-id-should-be-ignored" should have a valid fragment identifier',
       },
+      {
+        name: "with invalid heading with #L fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-heading-with-L-fragment/invalid-heading-with-L-fragment.md",
+        error: '"./awesome.md#L7abc" should have a valid fragment identifier',
+      },
+      {
+        name: "with a invalid line number fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-line-number-fragment/invalid-line-number-fragment.md",
+        error:
+          '"./awesome.md#L7" should have a valid fragment identifier, "./awesome.md#L7" should have at least 7 lines to be valid',
+      },
       {
         name: "with a non-existing anchor name fragment",
         fixturePath:
@@ -118,6 +131,11 @@ test("ensure the rule validates correctly", async (t) => {
         fixturePath:
           "test/fixtures/valid/existing-element-id-fragment/existing-element-id-fragment.md",
       },
+      {
+        name: "with an existing heading fragment (case insensitive)",
+        fixturePath:
+          "test/fixtures/valid/existing-heading-case-insensitive/existing-heading-case-insensitive.md",
+      },
       {
         name: "with an existing heading fragment",
         fixturePath:
@@ -128,6 +146,16 @@ test("ensure the rule validates correctly", async (t) => {
         fixturePath:
           "test/fixtures/valid/only-parse-markdown-files-for-fragments/only-parse-markdown-files-for-fragments.md",
       },
+      {
+        name: 'with valid heading "like" line number fragment',
+        fixturePath:
+          "test/fixtures/valid/valid-heading-like-number-fragment/valid-heading-like-number-fragment.md",
+      },
+      {
+        name: "with valid line number fragment",
+        fixturePath:
+          "test/fixtures/valid/valid-line-number-fragment/valid-line-number-fragment.md",
+      },
       {
         name: "with an existing file",
         fixturePath: "test/fixtures/valid/existing-file.md",

test/utils.test.js

@@ -5,6 +5,9 @@ const {
   convertHeadingToHTMLFragment,
   getMarkdownHeadings,
   getMarkdownIdOrAnchorNameFragments,
+  isValidIntegerString,
+  getNumberOfLines,
+  getLineNumberStringFromFragment,
 } = require("../src/utils.js")
 
 test("utils", async (t) => {
@@ -54,4 +57,23 @@ test("utils", async (t) => {
     assert.deepStrictEqual(getMarkdownIdOrAnchorNameFragments("<a>"), [])
     assert.deepStrictEqual(getMarkdownIdOrAnchorNameFragments("<a id=>"), [])
   })
+
+  await t.test("isValidIntegerString", async () => {
+    assert.strictEqual(isValidIntegerString("1"), true)
+    assert.strictEqual(isValidIntegerString("45"), true)
+    assert.strictEqual(isValidIntegerString("1abc"), false)
+    assert.strictEqual(isValidIntegerString("1.0"), false)
+  })
+
+  await t.test("getNumberOfLines", async () => {
+    assert.strictEqual(getNumberOfLines(""), 1)
+    assert.strictEqual(getNumberOfLines("Hello"), 1)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld"), 2)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld\n"), 3)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld\n\n"), 4)
+  })
+
+  await t.test("getLineNumberStringFromFragment", async () => {
+    assert.strictEqual(getLineNumberStringFromFragment("#L50"), "50")
+  })
 })