feat: create no-empty-images (#357)

Co-authored-by: Nitin Kumar <snitin315@gmail.com>

Author: lumirlumir

README.md

@@ -76,6 +76,7 @@ export default defineConfig([
 | [`fenced-code-language`](./docs/rules/fenced-code-language.md) | Require languages for fenced code blocks | yes |
 | [`heading-increment`](./docs/rules/heading-increment.md) | Enforce heading levels increment by one | yes |
 | [`no-duplicate-headings`](./docs/rules/no-duplicate-headings.md) | Disallow duplicate headings in the same document | no |
+| [`no-empty-images`](./docs/rules/no-empty-images.md) | Disallow empty images | yes |
 | [`no-empty-links`](./docs/rules/no-empty-links.md) | Disallow empty links | yes |
 | [`no-html`](./docs/rules/no-html.md) | Disallow HTML tags | no |
 | [`no-invalid-label-refs`](./docs/rules/no-invalid-label-refs.md) | Disallow invalid label references | yes |

docs/rules/no-empty-images.md

@@ -0,0 +1,39 @@
+# no-empty-images
+
+Disallow empty images.
+
+## Background
+
+In Markdown, it’s not always easy to spot when you’ve forgotten to provide a destination for an image. This is especially common when you’re writing something in Markdown and intend to insert an image, leaving the destination to fill in later, only to forget to go back and complete it. This often results in broken image links.
+
+## Rule Details
+
+This rule warns when it finds images that either don't have a URL specified or have only an empty fragment (`"#"`).
+
+Examples of incorrect code:
+
+```markdown
+![]()
+
+![ESLint Logo]()
+
+![](#)
+
+![Image](#)
+```
+
+Exmaples of correct code:
+
+```markdown
+![](https://eslint.org/image.png)
+
+![ESLint Logo](https://eslint.org/image.png)
+```
+
+## When Not to Use It
+
+If you aren't concerned with empty images, you can safely disable this rule.
+
+## Prior Art
+
+* [remark-lint-no-empty-url](https://github.com/remarkjs/remark-lint/tree/main/packages/remark-lint-no-empty-url)

src/rules/no-empty-images.js

@@ -0,0 +1,47 @@
+/**
+ * @fileoverview Rule to prevent empty images in Markdown.
+ * @author 루밀LuMir(lumirlumir)
+ */
+
+//-----------------------------------------------------------------------------
+// Type Definitions
+//-----------------------------------------------------------------------------
+
+/**
+ * @typedef {import("../types.ts").MarkdownRuleDefinition<{ RuleOptions: []; }>}
+ * NoEmptyImagesRuleDefinition
+ */
+
+//-----------------------------------------------------------------------------
+// Rule Definition
+//-----------------------------------------------------------------------------
+
+/** @type {NoEmptyImagesRuleDefinition} */
+export default {
+	meta: {
+		type: "problem",
+
+		docs: {
+			recommended: true,
+			description: "Disallow empty images",
+			url: "https://github.com/eslint/markdown/blob/main/docs/rules/no-empty-images.md",
+		},
+
+		messages: {
+			emptyImage: "Unexpected empty image found.",
+		},
+	},
+
+	create(context) {
+		return {
+			image(node) {
+				if (!node.url || node.url === "#") {
+					context.report({
+						loc: node.position,
+						messageId: "emptyImage",
+					});
+				}
+			},
+		};
+	},
+};

tests/rules/no-empty-images.test.js

@@ -0,0 +1,89 @@
+/**
+ * @fileoverview Tests for no-empty-images rule.
+ * @author 루밀LuMir(lumirlumir)
+ */
+
+//------------------------------------------------------------------------------
+// Imports
+//------------------------------------------------------------------------------
+
+import rule from "../../src/rules/no-empty-images.js";
+import markdown from "../../src/index.js";
+import { RuleTester } from "eslint";
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({
+	plugins: {
+		markdown,
+	},
+	language: "markdown/commonmark",
+});
+
+ruleTester.run("no-empty-images", rule, {
+	valid: ["![foo](bar)", "![foo](#bar)", "![foo](http://bar.com/image.png)"],
+	invalid: [
+		{
+			code: "![]()",
+			errors: [
+				{
+					messageId: "emptyImage",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 6,
+				},
+			],
+		},
+		{
+			code: "![](#)",
+			errors: [
+				{
+					messageId: "emptyImage",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 7,
+				},
+			],
+		},
+		{
+			code: "![foo]()",
+			errors: [
+				{
+					messageId: "emptyImage",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 9,
+				},
+			],
+		},
+		{
+			code: "![foo](#)",
+			errors: [
+				{
+					messageId: "emptyImage",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 10,
+				},
+			],
+		},
+		{
+			code: "![foo]( )",
+			errors: [
+				{
+					messageId: "emptyImage",
+					line: 1,
+					column: 1,
+					endLine: 1,
+					endColumn: 10,
+				},
+			],
+		},
+	],
+});