Chore: add core rule's tests

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "test/fixtures/eslint"]
+	path = test/fixtures/eslint
+	url = https://github.com/eslint/eslint.git

package.json

@@ -11,6 +11,7 @@
     "clean": "rimraf .nyc_output coverage",
     "coverage": "nyc report --reporter lcov && opener ./coverage/lcov-report/index.html",
     "lint": "eslint index.js \"test/*.js\"",
+    "postinstall": "git submodule update --init && cd test/fixtures/eslint && npm install",
     "postversion": "git push && git push --tags",
     "pretest": "npm run lint",
     "preversion": "npm test",

test/core-rules.js

@@ -0,0 +1,106 @@
+/**
+ * @author Toru Nagashima <https://github.com/mysticatea>
+ * @copyright 2016 Toru Nagashima. All rights reserved.
+ * See LICENSE file in root directory for full license.
+ */
+"use strict"
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const path = require("path")
+const fs = require("fs-extra")
+const RuleTester = require("./fixtures/eslint/lib/testers/rule-tester")
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const RULES_ROOT = path.join(__dirname, "fixtures/eslint/tests/lib/rules")
+const PARSER_PATH = path.resolve(__dirname, "../index.js")
+const originalRun = RuleTester.prototype.run
+
+/**
+ * Wrap the given code with a `<script>` tag.
+ *
+ * @param {string} code - The code to be wrapped.
+ * @returns {string} The wrapped code.
+ */
+function wrapCode(code) {
+    const eol = code.indexOf("\r\n") !== -1 ? "\r\n" : "\n"
+    return `<script>${eol}${code}${eol}</script>`
+}
+
+/**
+ * Modify the given test pattern to test with vue-eslint-parser.
+ *
+ * @param {string|object} pattern - The test pattern to be modified.
+ * @returns {object|null} The modified pattern.
+ */
+function modifyPattern(pattern) {
+    if (typeof pattern === "string") {
+        return {
+            code: wrapCode(pattern),
+            filename: "test.vue",
+            parser: PARSER_PATH,
+        }
+    }
+    if (pattern.parser != null || pattern.filename != null) {
+        return null
+    }
+
+    pattern.filename = "test.vue"
+    pattern.parser = PARSER_PATH
+    pattern.code = wrapCode(pattern.code)
+    if (pattern.output != null) {
+        pattern.output = wrapCode(pattern.output)
+    }
+    if (Array.isArray(pattern.errors)) {
+        for (const error of pattern.errors) {
+            if (typeof error === "object") {
+                if (error.line != null) {
+                    error.line += 1
+                }
+                if (error.endLine != null) {
+                    error.endLine += 1
+                }
+            }
+        }
+    }
+
+    return pattern
+}
+
+/**
+ * Run the given tests.
+ * This is used to replace `RuleTester.prototype.run`.
+ *
+ * @this {RuleTester}
+ * @param {string} ruleId - The rule ID.
+ * @param {object} impl - The rule implementation to be tested.
+ * @param {object} patterns - The test patterns.
+ * @returns {void}
+ */
+function overrideRun(ruleId, impl, patterns) {
+    return originalRun.call(this, ruleId, impl, {
+        valid: patterns.valid.map(modifyPattern).filter(Boolean),
+        invalid: patterns.invalid.map(modifyPattern).filter(Boolean),
+    })
+}
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+RuleTester.prototype.run = overrideRun
+try {
+    describe("Tests of ESLint core rules", () => {
+        for (const fileName of fs.readdirSync(RULES_ROOT)) {
+            require(path.join(RULES_ROOT, fileName))
+        }
+    })
+}
+finally {
+    RuleTester.prototype.run = originalRun
+}