From a563c082a5600509406361cb8a00ee3dda08cb65 Mon Sep 17 00:00:00 2001
From: Gabriel Kuznik <gabriel.kuznik@check24.de>
Date: Fri, 1 Dec 2023 12:33:48 +0100
Subject: [PATCH] Add rule MD055/table-missing-border (fixes #93, refs #1039,
 no generated files).

---
 .github/dictionary.txt                        |   1 +
 README.md                                     |   2 +
 doc-build/md055.md                            |  34 +++++
 lib/md055.js                                  |  27 ++++
 lib/rules.js                                  |   4 +-
 test/break-all-the-rules.md                   |   4 +
 test/html-comment-in-markdown-table.md        |   4 +
 test/long_lines_code.md                       |   2 -
 test/markdownlint-test.js                     |  18 ++-
 ...md033-cannot-read-property-of-undefined.md |   4 +
 test/table-missing-pipes.md                   | 140 ++++++++++++++++++
 11 files changed, 228 insertions(+), 12 deletions(-)
 create mode 100644 doc-build/md055.md
 create mode 100644 lib/md055.js
 create mode 100644 test/table-missing-pipes.md

diff --git a/.github/dictionary.txt b/.github/dictionary.txt
index 39cd1f71..51267844 100644
--- a/.github/dictionary.txt
+++ b/.github/dictionary.txt
@@ -37,6 +37,7 @@ eslint-plugin-markdownlint
 first-line-h1
 formatter
 fs
+GFM
 globbing
 grunt-markdownlint
 h1
diff --git a/README.md b/README.md
index 9c019221..3355233f 100644
--- a/README.md
+++ b/README.md
@@ -134,6 +134,7 @@ playground for learning and exploring.
 - **[MD052](doc/md052.md)** *reference-links-images* - Reference links and images should use a label that is defined
 - **[MD053](doc/md053.md)** *link-image-reference-definitions* - Link and image reference definitions should be needed
 - **[MD054](doc/md054.md)** *link-image-style* - Link and image style
+- **[MD055](doc/md055.md)** *table-missing-border* - Table is missing leading or trailing pipe character
 
 <!-- markdownlint-restore -->
 
@@ -175,6 +176,7 @@ rules at once.
 - **`ol`** - `MD029`, `MD030`, `MD032`
 - **`spaces`** - `MD018`, `MD019`, `MD020`, `MD021`, `MD023`
 - **`spelling`** - `MD044`
+- **`table`** - `MD055`
 - **`ul`** - `MD004`, `MD005`, `MD007`, `MD030`, `MD032`
 - **`url`** - `MD034`
 - **`whitespace`** - `MD009`, `MD010`, `MD012`, `MD027`, `MD028`, `MD030`,
diff --git a/doc-build/md055.md b/doc-build/md055.md
new file mode 100644
index 00000000..f29f3fef
--- /dev/null
+++ b/doc-build/md055.md
@@ -0,0 +1,34 @@
+This rule is triggered when a [GFM table][gfm-table] is missing a leading
+or trailing pipe character `|`.
+
+This table is missing pipes on both sides:
+
+```markdown
+| Heading | Heading |
+|---------|---------
+  Cell    | Cell    |
+```
+
+To fix this, make sure there is a pipe character at the start and end of the
+row:
+
+```markdown
+| Heading | Heading |
+|---------|---------|
+| Cell    | Cell    |
+```
+
+Note that text immediately below a table is treated as part of the table and
+will trigger this rule:
+
+```markdown
+| Heading | Heading |
+|---------|---------|
+| Cell    | Cell    |
+This text will trigger the rule
+```
+
+Rationale: Some parsers have difficulty with tables that are missing their
+leading or trailing pipe characters.
+
+[gfm-table]: https://github.github.com/gfm/#tables-extension-
diff --git a/lib/md055.js b/lib/md055.js
new file mode 100644
index 00000000..d302d366
--- /dev/null
+++ b/lib/md055.js
@@ -0,0 +1,27 @@
+// @ts-check
+
+"use strict";
+
+const { addErrorContext } = require("../helpers");
+const { filterByTypes } = require("../helpers/micromark.cjs");
+
+module.exports = {
+    "names": [ "MD055", "table-missing-border" ],
+    "description": "Table is missing leading or trailing pipe character",
+    "tags": [ "table" ],
+    "function": function MD055(params, onError) {
+        const tables = filterByTypes(params.parsers.micromark.tokens, [ "table" ]);
+        for (const table of tables) {
+            const rows = filterByTypes(table.children, [ "tableRow", "tableDelimiterRow" ]);
+            for (const row of rows) {
+                const { startLine, text } = row;
+                if (!text.startsWith("|")) {
+                    addErrorContext(onError, startLine, text, true);
+                }
+                if (!text.endsWith("|")) {
+                    addErrorContext(onError, startLine, text, false, true);
+                }
+            }
+        }
+    }
+}
diff --git a/lib/rules.js b/lib/rules.js
index eb946277..f6a7564b 100644
--- a/lib/rules.js
+++ b/lib/rules.js
@@ -51,8 +51,8 @@ const rules = [
   require("./md051"),
   require("./md052"),
   require("./md053"),
-  require("./md054")
-  // md055: See https://github.com/markdownlint/markdownlint
+  require("./md054"),
+  require("./md055")
   // md056: See https://github.com/markdownlint/markdownlint
   // md057: See https://github.com/markdownlint/markdownlint
 ];
diff --git a/test/break-all-the-rules.md b/test/break-all-the-rules.md
index b8b6d19b..3269fff0 100644
--- a/test/break-all-the-rules.md
+++ b/test/break-all-the-rules.md
@@ -105,6 +105,10 @@ Strong **with** different style {MD050}
 <!-- markdownlint-disable-next-line MD053 -->
 [url]: https://example.com/page
 
+| table  | header |
+|--------|--------|
+ {MD055} | cell   |
+
 <!-- markdownlint-configure-file {
   "required-headings": {
     "headings": [
diff --git a/test/html-comment-in-markdown-table.md b/test/html-comment-in-markdown-table.md
index 3d8447b4..ad0a91b1 100644
--- a/test/html-comment-in-markdown-table.md
+++ b/test/html-comment-in-markdown-table.md
@@ -51,3 +51,7 @@
 | cell  | <!--           \
 | cell  | `{MD038} ` --> |
 | cell  | cell           |
+
+<!-- markdownlint-configure-file {
+  "table-missing-border": false
+} -->
diff --git a/test/long_lines_code.md b/test/long_lines_code.md
index 370a9199..8d366550 100644
--- a/test/long_lines_code.md
+++ b/test/long_lines_code.md
@@ -29,7 +29,6 @@ This is a short line.
 | Content Cell   | Content Cell   | Content Cell   | Content Cell   | Content Cell   | Content Cell   |
 | ============== | ============== | ============== | ============== | ============== | ============== |
 | Footer Cell    | Footer Cell    | Footer Cell    | Footer Cell    | Footer Cell    | Footer Cell    |
-{: rules="groups"}
 
 This is a very very very very very very very very very very very very very very very very very very very very long line. {MD013}
 
@@ -44,7 +43,6 @@ Another line.
 | Content Cell   | Content Cell   | Content Cell   | Content Cell   | Content Cell   | Content Cell   |
 | ============== | ============== | ============== | ============== | ============== | ============== |
 | Footer Cell    | Footer Cell    | Footer Cell    | Footer Cell    | Footer Cell    | Footer Cell    |
-{: rules="groups"}
 
 <!-- markdownlint-configure-file {
   "line-length": {
diff --git a/test/markdownlint-test.js b/test/markdownlint-test.js
index 4530bf8f..c2820a4b 100644
--- a/test/markdownlint-test.js
+++ b/test/markdownlint-test.js
@@ -83,7 +83,7 @@ test("projectFiles", (t) => {
       "schema/*.md"
     ]))
     .then((files) => {
-      t.is(files.length, 58);
+      t.is(files.length, 59);
       const options = {
         files,
         "config": require("../.markdownlint.json")
@@ -476,13 +476,14 @@ test("styleAll", (t) => new Promise((resolve) => {
         "MD042": [ 81 ],
         "MD045": [ 85 ],
         "MD046": [ 49, 73, 77 ],
-        "MD047": [ 126 ],
+        "MD047": [ 130 ],
         "MD048": [ 77 ],
         "MD049": [ 90 ],
         "MD050": [ 94 ],
         "MD051": [ 96 ],
         "MD052": [ 98 ],
-        "MD053": [ 100 ]
+        "MD053": [ 100 ],
+        "MD055": [ 110 ]
       }
     };
     // @ts-ignore
@@ -525,13 +526,14 @@ test("styleRelaxed", (t) => new Promise((resolve) => {
         "MD042": [ 81 ],
         "MD045": [ 85 ],
         "MD046": [ 49, 73, 77 ],
-        "MD047": [ 126 ],
+        "MD047": [ 130 ],
         "MD048": [ 77 ],
         "MD049": [ 90 ],
         "MD050": [ 94 ],
         "MD051": [ 96 ],
         "MD052": [ 98 ],
-        "MD053": [ 100 ]
+        "MD053": [ 100 ],
+        "MD055": [ 110 ]
       }
     };
     // @ts-ignore
@@ -841,7 +843,7 @@ test("customFileSystemAsync", (t) => new Promise((resolve) => {
 }));
 
 test("readme", async(t) => {
-  t.plan(121);
+  t.plan(124);
   const tagToRules = {};
   for (const rule of rules) {
     for (const tag of rule.tags) {
@@ -916,7 +918,7 @@ test("readme", async(t) => {
 });
 
 test("validateJsonUsingConfigSchemaStrict", async(t) => {
-  t.plan(171);
+  t.plan(173);
   // @ts-ignore
   const ajv = new Ajv(ajvOptions);
   const validateSchemaStrict = ajv.compile(configSchemaStrict);
@@ -1036,7 +1038,7 @@ test("validateConfigExampleJson", async(t) => {
 });
 
 test("allBuiltInRulesHaveValidUrl", (t) => {
-  t.plan(144);
+  t.plan(147);
   for (const rule of rules) {
     // @ts-ignore
     t.truthy(rule.information);
diff --git a/test/md033-cannot-read-property-of-undefined.md b/test/md033-cannot-read-property-of-undefined.md
index 8b1d1838..96f0820d 100644
--- a/test/md033-cannot-read-property-of-undefined.md
+++ b/test/md033-cannot-read-property-of-undefined.md
@@ -9,3 +9,7 @@ Head    | Head
 <br/>   | {MD033}
 text    | text
 {MD033} | <b>text</b>
+
+<!-- markdownlint-configure-file {
+  "table-missing-border": false
+} -->
diff --git a/test/table-missing-pipes.md b/test/table-missing-pipes.md
new file mode 100644
index 00000000..781d1ecd
--- /dev/null
+++ b/test/table-missing-pipes.md
@@ -0,0 +1,140 @@
+# Table Missing Pipes
+
+## Bad Header Row
+
+| Table | {MD055}
+|-------|---------|
+
+  Table | {MD055} |
+|-------|---------|
+
+  Table | {MD055}
+|-------|---------|
+
+## Bad Separator Row
+
+| Table | Header |
+|-------|---------
+
+{MD055:17}
+
+| Table | Header |
+ -------|--------|
+
+{MD055:22}
+
+| Table | Header |
+ -------|--------
+
+{MD055:27}
+
+## Missing everything
+
+ {MD055} | Header
+---------|-------
+ {MD055} | cell
+
+{MD055:34}
+
+ {MD055} | Header
+--------:|:-----:
+ {MD055} | cell
+
+{MD055:40}
+
+## Missing trailing pipe
+
+| Table   | Header |
+|--------:|:-------|
+| {MD055} | cell
+
+| Table   | Header |
+|---------|--------|
+| {MD055} | cell
+| cell    | cell   |
+| cell    | cell   |
+
+| Table   | Header |
+|---------|--------|
+| cell    | cell   |
+| {MD055} | cell
+| cell    | cell   |
+
+| Table   | Header |
+|---------|--------|
+| cell    | cell   |
+| cell    | cell   |
+| {MD055} | cell
+
+## Missing leading pipe
+
+| Table  | Header |
+|-------:|:-------|
+ {MD055} | cell   |
+
+| Table  | Header |
+|--------|--------|
+ {MD055} | cell   |
+| cell   | cell   |
+| cell   | cell   |
+
+| Table  | Header |
+|--------|--------|
+| cell   | cell   |
+ {MD055} | cell   |
+| cell   | cell   |
+
+| Table  | Header |
+|--------|--------|
+| cell   | cell   |
+| cell   | cell   |
+ {MD055} | cell   |
+
+## Missing both sides
+
+| Table  | Header |
+|-------:|:-------|
+ {MD055} | cell
+
+| Table  | Header |
+|--------|--------|
+ {MD055} | cell
+| cell   | cell   |
+| cell   | cell   |
+
+| Table  | Header |
+|--------|--------|
+| cell   | cell   |
+ {MD055} | cell
+| cell   | cell   |
+
+| Table  | Header |
+|--------|--------|
+| cell   | cell   |
+| cell   | cell   |
+ {MD055} | cell
+
+## No false-positive
+
+| Table | Header |
+|-------|--------|
+| cell  | cell   |
+
+| Table | Header |
+|-------|--------|
+| cell  | cell   |
+| cell  | cell   |
+| cell  | cell   |
+
+## No trailing blank line
+
+| Table | Header |
+|-------|--------|
+| cell  | cell   |
+{MD055} Text
+
+## Markdown Combination
+
+> | Table | Header |
+> |-------|--------|
+> -{MD055}| cell   |