From 40b62eac09d9eb78e6d612daed1cb52b17c29dff Mon Sep 17 00:00:00 2001
From: Kai Cataldo <kaicataldo@gmail.com>
Date: Thu, 15 Aug 2019 12:09:01 -0400
Subject: [PATCH 1/3] Update: improve error messaging when validating
 ecmaVersion

---
 lib/espree.js             | 42 ++++++++++++++++++++-------------------
 tests/lib/ecma-version.js |  2 +-
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/lib/espree.js b/lib/espree.js
index 0d65018b..bb1d5891 100644
--- a/lib/espree.js
+++ b/lib/espree.js
@@ -18,28 +18,30 @@ const tokTypes = Object.assign({}, acorn.tokTypes, jsx.tokTypes);
  * @returns {number} normalized ECMAScript version
  */
 function normalizeEcmaVersion(ecmaVersion = DEFAULT_ECMA_VERSION) {
-    if (typeof ecmaVersion === "number") {
-        let version = ecmaVersion;
+    if (typeof ecmaVersion !== "number") {
+        throw new Error("ecmaVersion must be a number.");
+    }
 
-        // Calculate ECMAScript edition number from official year version starting with
-        // ES2015, which corresponds with ES6 (or a difference of 2009).
-        if (version >= 2015) {
-            version -= 2009;
-        }
+    let version = ecmaVersion;
 
-        switch (version) {
-            case 3:
-            case 5:
-            case 6:
-            case 7:
-            case 8:
-            case 9:
-            case 10:
-            case 11:
-                return version;
-
-            // no default
-        }
+    // Calculate ECMAScript edition number from official year version starting with
+    // ES2015, which corresponds with ES6 (or a difference of 2009).
+    if (version >= 2015) {
+        version -= 2009;
+    }
+
+    switch (version) {
+        case 3:
+        case 5:
+        case 6:
+        case 7:
+        case 8:
+        case 9:
+        case 10:
+        case 11:
+            return version;
+
+        // no default
     }
 
     throw new Error("Invalid ecmaVersion.");
diff --git a/tests/lib/ecma-version.js b/tests/lib/ecma-version.js
index 64409853..4e6cf349 100644
--- a/tests/lib/ecma-version.js
+++ b/tests/lib/ecma-version.js
@@ -152,7 +152,7 @@ describe("ecmaVersion", () => {
                         loc: true
                     }
                 );
-            }, /Invalid ecmaVersion/);
+            }, /ecmaVersion must be a number/);
         });
 
         it("Should throw error when using module in pre-ES6", () => {

From 8e69dabd1aa5d9dce4df48339d5ff6d0a316dc0d Mon Sep 17 00:00:00 2001
From: Kai Cataldo <kaicataldo@gmail.com>
Date: Thu, 15 Aug 2019 12:29:13 -0400
Subject: [PATCH 2/3] Print found type in error message

---
 lib/espree.js             | 6 ++++--
 tests/lib/ecma-version.js | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/espree.js b/lib/espree.js
index bb1d5891..013273db 100644
--- a/lib/espree.js
+++ b/lib/espree.js
@@ -18,8 +18,10 @@ const tokTypes = Object.assign({}, acorn.tokTypes, jsx.tokTypes);
  * @returns {number} normalized ECMAScript version
  */
 function normalizeEcmaVersion(ecmaVersion = DEFAULT_ECMA_VERSION) {
-    if (typeof ecmaVersion !== "number") {
-        throw new Error("ecmaVersion must be a number.");
+    const ecmaVersionType = typeof ecmaVersion;
+
+    if (ecmaVersionType !== "number") {
+        throw new Error(`ecmaVersion must be a number. Received value of type ${ecmaVersionType} instead.`);
     }
 
     let version = ecmaVersion;
diff --git a/tests/lib/ecma-version.js b/tests/lib/ecma-version.js
index 4e6cf349..d72d2abe 100644
--- a/tests/lib/ecma-version.js
+++ b/tests/lib/ecma-version.js
@@ -152,7 +152,7 @@ describe("ecmaVersion", () => {
                         loc: true
                     }
                 );
-            }, /ecmaVersion must be a number/);
+            }, /ecmaVersion must be a number. Received value of type string instead/);
         });
 
         it("Should throw error when using module in pre-ES6", () => {

From 93a3d53b2e435297e6547071a1302a195a8a5541 Mon Sep 17 00:00:00 2001
From: Kai Cataldo <kaicataldo@gmail.com>
Date: Thu, 15 Aug 2019 12:35:43 -0400
Subject: [PATCH 3/3] Inline typeof check

---
 lib/espree.js | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/lib/espree.js b/lib/espree.js
index 013273db..64908a78 100644
--- a/lib/espree.js
+++ b/lib/espree.js
@@ -18,10 +18,8 @@ const tokTypes = Object.assign({}, acorn.tokTypes, jsx.tokTypes);
  * @returns {number} normalized ECMAScript version
  */
 function normalizeEcmaVersion(ecmaVersion = DEFAULT_ECMA_VERSION) {
-    const ecmaVersionType = typeof ecmaVersion;
-
-    if (ecmaVersionType !== "number") {
-        throw new Error(`ecmaVersion must be a number. Received value of type ${ecmaVersionType} instead.`);
+    if (typeof ecmaVersion !== "number") {
+        throw new Error(`ecmaVersion must be a number. Received value of type ${typeof ecmaVersion} instead.`);
     }
 
     let version = ecmaVersion;