From f1be1a3462b3252ee45a739781cda196fe59d4b1 Mon Sep 17 00:00:00 2001
From: Janis Lesinskis <shuttle1987@users.noreply.github.com>
Date: Fri, 23 Sep 2016 22:45:33 +1000
Subject: [PATCH] Invalid input error message (#540)

* Added check for type of expressions passed to parseTree function
* Added tests for bad input raising exception
* Added test for supported types NOT throwing exception
* Added test case for parser taking String objects
---
 src/parseTree.js   |  3 +++
 test/katex-spec.js | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/parseTree.js b/src/parseTree.js
index 3adba82..44f38c6 100644
--- a/src/parseTree.js
+++ b/src/parseTree.js
@@ -9,6 +9,9 @@ var Parser = require("./Parser");
  * Parses an expression using a Parser, then returns the parsed result.
  */
 var parseTree = function(toParse, settings) {
+    if (!(typeof toParse === 'string' || toParse instanceof String)) {
+        throw new TypeError('KaTeX can only parse string typed expression');
+    }
     var parser = new Parser(toParse, settings);
 
     return parser.parse();
diff --git a/test/katex-spec.js b/test/katex-spec.js
index af9688d..57aad4e 100644
--- a/test/katex-spec.js
+++ b/test/katex-spec.js
@@ -1382,6 +1382,33 @@ describe("An HTML font tree-builder", function() {
         span = "<span class=\"mord mathbb\" style=\"color:blue;\">R</span>";
         expect(markup).toContain(span);
     });
+
+    it("should throw TypeError when the expression is of the wrong type", function() {
+        expect(function() {
+            katex.renderToString({badInputType: "yes"});
+        }).toThrowError(TypeError);
+        expect(function() {
+            katex.renderToString([1, 2]);
+        }).toThrowError(TypeError);
+        expect(function() {
+            katex.renderToString(undefined);
+        }).toThrowError(TypeError);
+        expect(function() {
+            katex.renderToString(null);
+        }).toThrowError(TypeError);
+        expect(function() {
+            katex.renderToString(1.234);
+        }).toThrowError(TypeError);
+    });
+
+    it("should not throw TypeError when the expression is a supported type", function() {
+        expect(function() {
+            katex.renderToString("\\sqrt{123}");
+        }).not.toThrowError(TypeError);
+        expect(function() {
+            katex.renderToString(new String("\\sqrt{123}"));
+        }).not.toThrowError(TypeError);
+    });
 });
 
 
@@ -1878,3 +1905,15 @@ describe("A macro expander", function() {
         });
     });
 });
+
+describe("A parser taking String objects", function() {
+    it("should not fail on an empty String object", function() {
+        expect(new String("")).toParse();
+    });
+
+    it("should parse the same as a regular string", function() {
+        expect(new String("xy")).toParseLike("xy");
+        expect(new String("\\div")).toParseLike("\\div");
+        expect(new String("\\frac 1 2")).toParseLike("\\frac 1 2");
+    });
+});