From 78a13930fb7335e664c60c361af87bb1ed8e7450 Mon Sep 17 00:00:00 2001
From: eric wang <eric@canva.com>
Date: Sun, 21 Jun 2020 17:44:30 +1000
Subject: [PATCH] hide linterMapSymbol

---
 lib/rule-tester/index.js             |  4 +---
 lib/rule-tester/rule-tester.js       | 25 +++++++++++++++++++++----
 tests/lib/rule-tester/rule-tester.js |  7 ++++---
 3 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/lib/rule-tester/index.js b/lib/rule-tester/index.js
index f52d14027c5..35191635185 100644
--- a/lib/rule-tester/index.js
+++ b/lib/rule-tester/index.js
@@ -1,5 +1,3 @@
 "use strict";
 
-module.exports = {
-    RuleTester: require("./rule-tester")
-};
+module.exports = require("./rule-tester");
diff --git a/lib/rule-tester/rule-tester.js b/lib/rule-tester/rule-tester.js
index a891d127001..ad4b87087b0 100644
--- a/lib/rule-tester/rule-tester.js
+++ b/lib/rule-tester/rule-tester.js
@@ -100,6 +100,12 @@ const espreePath = require.resolve("espree");
  * @property {number} [endColumn] The 1-based column number of the reported end location.
  */
 
+/**
+ * The private data for `RuleTester` instance.
+ * @typedef {Object} RuleTesterInternalSlots
+ * @property {symbol} injectedLinterMapSymbol symbol key for injected linterMap
+ */
+
 //------------------------------------------------------------------------------
 // Private Members
 //------------------------------------------------------------------------------
@@ -312,6 +318,14 @@ function describeDefaultHandler(text, method) {
     return method.call(this);
 }
 
+/**
+ * The map to store private data.
+ * @type {RuleTesterInternalSlots}
+ */
+const internalSlotsMap = {
+    injectedLinterMapSymbol: Symbol("linterMap")
+};
+
 class RuleTester {
 
     /**
@@ -417,9 +431,9 @@ class RuleTester {
      * @param {{
      *   valid: (ValidTestCase | string)[],
      *   invalid: InvalidTestCase[],
-     *   linterMapDevOnly?: Map<string | undefined, Linter>
+     *   Symbol("linterMap")?: Map<string | undefined, Linter>
      * }} test The collection of tests to run.
-     * test.linterMapDevOnly is for testing purpose
+     * test.[Symbol.for("linterMap")] is for testing purpose
      * @returns {void}
      */
     run(ruleName, rule, test) {
@@ -438,7 +452,7 @@ class RuleTester {
          * Injection of value in `test` is for test purpose.
          * @type {Map<string | undefined, Linter>}
          */
-        const { linterMapDevOnly: linterMap = new Map() } = test;
+        const { [internalSlotsMap.injectedLinterMapSymbol]: linterMap = new Map() } = test;
 
         requiredScenarios.forEach(scenarioType => {
             if (lodash.isNil(test[scenarioType])) {
@@ -912,4 +926,7 @@ class RuleTester {
 
 RuleTester[DESCRIBE] = RuleTester[IT] = null;
 
-module.exports = RuleTester;
+module.exports = {
+    RuleTester,
+    internalSlotsMap
+};
diff --git a/tests/lib/rule-tester/rule-tester.js b/tests/lib/rule-tester/rule-tester.js
index 929f903eb2f..c755727c093 100644
--- a/tests/lib/rule-tester/rule-tester.js
+++ b/tests/lib/rule-tester/rule-tester.js
@@ -9,7 +9,7 @@
 //------------------------------------------------------------------------------
 const sinon = require("sinon"),
     EventEmitter = require("events"),
-    { RuleTester } = require("../../../lib/rule-tester"),
+    { RuleTester, internalSlotsMap } = require("../../../lib/rule-tester"),
     { Linter } = require("../../../lib/linter"),
     assert = require("chai").assert,
     nodeAssert = require("assert"),
@@ -759,7 +759,8 @@ describe("RuleTester", () => {
             [undefined, linter]
         ]);
 
-        // ruleTester = new RuleTester({ linterMapDevOnly: linterMap });
+        const { injectedLinterMapSymbol } = internalSlotsMap;
+
         ruleTester = new RuleTester();
         ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
             valid: [
@@ -774,7 +775,7 @@ describe("RuleTester", () => {
                     errors: [{ line: 1 }]
                 }
             ],
-            linterMapDevOnly: linterMap
+            [injectedLinterMapSymbol]: linterMap
         });
         assert.strictEqual(spy.args[1][1].parser, require.resolve("esprima"));
     });