Add test cases

docs/rules/GH003-no-empty-string-alt.md

@@ -0,0 +1,35 @@
+# GH003 No empty string alt
+
+## Rule details
+
+This rule is _off_ by default and is only applicable for GitHub rendered markdown.
+
+Currently, all images on github.com are automatically wrapped in an anchor tag.
+
+As a result, images that are intentionally marked as decorative (via `alt=""``) end up as a link without an accessible name. This is confusing for assistive technology users. 
+
+This rule can be enabled to enforce that the alt attribute is always set to descriptive text. 
+
+This rule should be removed once this behavior is updated on GitHub's UI.
+
+## Examples
+
+### Incorrect 👎
+
+```md
+![""](cat.png)
+```
+
+```html
+<img src="cat.png" alt="">
+```
+
+### Correct 👍
+
+```md
+![Mona Lisa](mona.png)
+```
+
+```html
+<img src="mona.png" alt="Mona Lisa, the Octocat">
+```

test/no-empty-string-alt.test.js

@@ -0,0 +1,84 @@
+const noEmptyStringAltRule = require("../src/rules/no-empty-string-alt");
+const runTest = require("./utils/run-test").runTest;
+
+describe("GH003: No Empty String Alt", () => {
+  describe("successes", () => {
+    test("inline", async () => {
+      const strings = [
+        "![Chart with a single root node reading 'Example'](https://user-images.githubusercontent.com/abcdef.png)",
+      ];
+
+      const results = await runTest(strings, noEmptyStringAltRule);
+
+      for (const result of results) {
+        expect(result).not.toBeDefined();
+      }
+    });
+    test("html image", async () => {
+      const strings = [
+        '<img alt="A helpful description" src="https://user-images.githubusercontent.com/abcdef.png">',
+      ];
+
+      const results = await runTest(strings, noEmptyStringAltRule);
+
+      for (const result of results) {
+        expect(result).not.toBeDefined();
+      }
+    });
+  });
+  describe("failures", () => {
+    test("markdown example", async () => {
+      const strings = [
+        "![''](https://user-images.githubusercontent.com/abcdef.png)",
+        '![""](https://user-images.githubusercontent.com/abcdef.png)',
+      ];
+
+      const results = await runTest(strings, noEmptyStringAltRule);
+
+      const failedRules = results
+        .map((result) => result.ruleNames)
+        .flat()
+        .filter((name) => !name.includes("GH"));
+
+      expect(failedRules).toHaveLength(2);
+      for (const rule of failedRules) {
+        expect(rule).toBe("no-empty-string-alt");
+      }
+    });
+
+    test("HTML example", async () => {
+      const strings = [
+        '<img alt="" src="https://user-images.githubusercontent.com/abcdef.png">',
+        "<img alt='' src='https://user-images.githubusercontent.com/abcdef.png'>",
+      ];
+
+      const results = await runTest(strings, noEmptyStringAltRule);
+
+      const failedRules = results
+        .map((result) => result.ruleNames)
+        .flat()
+        .filter((name) => !name.includes("GH"));
+
+      expect(failedRules).toHaveLength(2);
+      for (const rule of failedRules) {
+        expect(rule).toBe("no-empty-string-alt");
+      }
+    });
+
+    test("error message", async () => {
+      const strings = [
+        "![''](https://user-images.githubusercontent.com/abcdef.png)",
+        '<img alt="" src="https://user-images.githubusercontent.com/abcdef.png">',
+      ];
+
+      const results = await runTest(strings, noEmptyStringAltRule);
+
+      expect(results[0].ruleDescription).toMatch(
+        "Please provide an alternative text for the image.",
+      );
+      expect(results[1].ruleDescription).toMatch(
+        "Please provide an alternative text for the image.",
+      );
+    });
+  });
+});

test/usage.test.js

@@ -4,8 +4,11 @@ describe("usage", () => {
   describe("default export", () => {
     test("custom rules on default export", () => {
       const rules = githubMarkdownLint;
-      expect(rules).toHaveLength(2);
+      expect(rules).toHaveLength(3);
+
       expect(rules[0].names).toEqual(["GH001", "no-default-alt-text"]);
+      expect(rules[1].names).toEqual(["GH002", "no-generic-link-text"]);
+      expect(rules[2].names).toEqual(["GH003", "no-empty-string-alt"]);
     });
   });
   describe("init method", () => {
@@ -17,6 +20,7 @@ describe("usage", () => {
         "no-space-in-links": false,
         "single-h1": true,
         "no-emphasis-as-header": true,
+        "no-empty-string-alt": false,
         "heading-increment": true,
         "no-generic-link-text": true,
         "ul-style": {