[Tests] add test case for #1645

Author: ljharb

.eslintignore

@@ -4,6 +4,7 @@ coverage
 node_modules
 tests/files/malformed.js
 tests/files/with-syntax-error
+tests/files/just-json-files/invalid.json
 resolvers/webpack/test/files
 # we want to ignore "tests/files" here, but unfortunately doing so would
 # interfere with unit test and fail it for some reason.

package.json

@@ -77,6 +77,7 @@
     "eslint-module-utils": "file:./utils",
     "eslint-plugin-eslint-plugin": "^2.2.1",
     "eslint-plugin-import": "2.x",
+    "eslint-plugin-json": "^2.1.1",
     "fs-copy-file-sync": "^1.1.1",
     "glob": "^7.1.6",
     "in-publish": "^2.0.0",

tests/files/just-json-files/.eslintrc.json

@@ -0,0 +1,22 @@
+{
+  "root": true,
+
+  "plugins": ["import", "json"],
+
+  "rules": {
+    "import/no-unused-modules": [
+      "error",
+      {
+        "missingExports": false,
+        "unusedExports": true
+      }
+    ]
+  },
+
+  "overrides": [
+    {
+      "files": "*.json",
+      "extends": "plugin:json/recommended"
+    }
+  ]
+}

tests/files/just-json-files/invalid.json

@@ -0,0 +1 @@
+,

tests/src/cli.js

@@ -1,8 +1,12 @@
 /**
  * tests that require fully booting up ESLint
  */
+import path from 'path'
+
 import { expect } from 'chai'
 import { CLIEngine } from 'eslint'
+import eslintPkg from 'eslint/package.json'
+import semver from 'semver'
 
 describe('CLI regression tests', function () {
   describe('issue #210', function () {
@@ -21,4 +25,55 @@ describe('CLI regression tests', function () {
       expect(() => cli.executeOnFiles(['./tests/files/issue210.js'])).not.to.throw(Error)
     })
   })
+
+  describe('issue #1645', function () {
+    let cli
+    beforeEach(function () {
+      if (semver.satisfies(eslintPkg.version, '< 6')) {
+        this.skip()
+      } else {
+        cli = new CLIEngine({
+          useEslintrc: false,
+          configFile: './tests/files/just-json-files/.eslintrc.json',
+          rulePaths: ['./src/rules'],
+          ignore: false,
+        })
+      }
+    })
+
+    it('throws an error on invalid JSON', function () {
+      const invalidJSON = './tests/files/just-json-files/invalid.json'
+      const results = cli.executeOnFiles([invalidJSON])
+      expect(results).to.eql({
+        results: [
+          {
+            filePath: path.resolve(invalidJSON),
+            messages: [
+              {
+                column: 2,
+                endColumn: 3,
+                endLine: 1,
+                line: 1,
+                message: 'Expected a JSON object, array or literal.',
+                nodeType: results.results[0].messages[0].nodeType, // we don't care about this one
+                ruleId: 'json/*',
+                severity: 2,
+                source: '\n',
+              },
+            ],
+            errorCount: 1,
+            warningCount: 0,
+            fixableErrorCount: 0,
+            fixableWarningCount: 0,
+            source: ',\n',
+          },
+        ],
+        errorCount: 1,
+        warningCount: 0,
+        fixableErrorCount: 0,
+        fixableWarningCount: 0,
+        usedDeprecatedRules: results.usedDeprecatedRules, // we don't care about this one
+      })
+    })
+  })
 })