Add tests for MD013/line-length edge case behavior.

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

@@ -42078,6 +42078,27 @@ Generated by [AVA](https://avajs.dev).
       <!-- markdownlint-disable-file descriptive-link-text -->`,
     }
 
+## long-lines-negative-line-length.md
+
+> Snapshot 1
+
+    {
+      errors: [],
+      fixed: `# Long Lines Negative Line Length␊
+      ␊
+      Text text text text text text text text text text text text text text text text text text text text.␊
+      ␊
+      This is an invalid configuration, but present in the wild and (for backward compatibility) disables the rule:␊
+      <https://github.com/electron/lint-roller/blob/1e062bda146160afb8eb232966287d5edb20e0a4/configs/markdownlint.json#L9>␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "line-length": {␊
+          "line_length": -1␊
+        }␊
+      } -->␊
+      `,
+    }
+
 ## long-lines-short-code.md
 
 > Snapshot 1
@@ -42637,6 +42658,121 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## long-lines-thresholds.md
+
+> Snapshot 1
+
+    {
+      errors: [
+        {
+          errorContext: null,
+          errorDetail: 'Expected: 40; Actual: 42',
+          errorRange: [
+            41,
+            2,
+          ],
+          fixInfo: null,
+          lineNumber: 8,
+          ruleDescription: 'Line length',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md013.md',
+          ruleNames: [
+            'MD013',
+            'line-length',
+          ],
+          severity: 'error',
+        },
+        {
+          errorContext: null,
+          errorDetail: 'Expected: 30; Actual: 32',
+          errorRange: [
+            31,
+            2,
+          ],
+          fixInfo: null,
+          lineNumber: 14,
+          ruleDescription: 'Line length',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md013.md',
+          ruleNames: [
+            'MD013',
+            'line-length',
+          ],
+          severity: 'error',
+        },
+        {
+          errorContext: null,
+          errorDetail: 'Expected: 20; Actual: 22',
+          errorRange: [
+            21,
+            2,
+          ],
+          fixInfo: null,
+          lineNumber: 20,
+          ruleDescription: 'Line length',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md013.md',
+          ruleNames: [
+            'MD013',
+            'line-length',
+          ],
+          severity: 'error',
+        },
+        {
+          errorContext: null,
+          errorDetail: 'Expected: 20; Actual: 22',
+          errorRange: [
+            21,
+            2,
+          ],
+          fixInfo: null,
+          lineNumber: 26,
+          ruleDescription: 'Line length',
+          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md013.md',
+          ruleNames: [
+            'MD013',
+            'line-length',
+          ],
+          severity: 'error',
+        },
+      ],
+      fixed: `# Long Lines Thresholds␊
+      ␊
+      00000000011111111112222222222333333333344444444445␊
+      12345678901234567890123456789012345678901234567890␊
+      ␊
+      Texxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx t␊
+      ␊
+      Texxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx t␊
+      ␊
+      {MD013:-2}␊
+      ␊
+      ## Texxxxxxxxxxxxxxxxxxxxxxxx t␊
+      ␊
+      ## Texxxxxxxxxxxxxxxxxxxxxxxxx t␊
+      ␊
+      {MD013:-2}␊
+      ␊
+      \`\`\`text␊
+      Texxxxxxxxxxxxxxxxx t␊
+      Texxxxxxxxxxxxxxxxxx t␊
+      \`\`\`␊
+      ␊
+      {MD013:-3}␊
+      ␊
+          Texxxxxxxxxxxxx t␊
+          Texxxxxxxxxxxxxx t␊
+      ␊
+      {MD013:-2}␊
+      ␊
+      <!-- markdownlint-configure-file {␊
+        "code-block-style": false,␊
+        "line-length": {␊
+          "line_length": 40,␊
+          "heading_line_length": 30,␊
+          "code_block_line_length": 20␊
+        }␊
+      } -->␊
+      `,
+    }
+
 ## long_lines.md
 
 > Snapshot 1