[Breaking] throws: bring into line with node’s assert.throws

Author: ljharb

.editorconfig

@@ -7,7 +7,7 @@ end_of_line = lf
 charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
-max_line_length = 140
+max_line_length = 180
 block_comment_start = /*
 block_comment =  *
 block_comment_end = */

lib/test.js

@@ -8,8 +8,10 @@ var isRegExp = require('is-regex');
 var trim = require('string.prototype.trim');
 var bind = require('function-bind');
 var forEach = require('for-each');
+var inspect = require('object-inspect');
 var isEnumerable = bind.call(Function.call, Object.prototype.propertyIsEnumerable);
 var toLowerCase = bind.call(Function.call, String.prototype.toLowerCase);
+var isProto = bind.call(Function.call, Object.prototype.isPrototypeOf);
 
 module.exports = Test;
 
@@ -514,7 +516,7 @@ Test.prototype['throws'] = function (fn, expected, msg, extra) {
         fn();
     } catch (err) {
         caught = { error: err };
-        if ((err != null) && (!isEnumerable(err, 'message') || !has(err, 'message'))) {
+        if (err != null && (!isEnumerable(err, 'message') || !has(err, 'message'))) {
             var message = err.message;
             delete err.message;
             err.message = message;
@@ -523,16 +525,42 @@ Test.prototype['throws'] = function (fn, expected, msg, extra) {
 
     var passed = caught;
 
-    if (isRegExp(expected)) {
-        passed = expected.test(caught && caught.error);
-        expected = String(expected);
-    }
-
-    if (typeof expected === 'function' && caught) {
-        passed = caught.error instanceof expected;
+    if (caught) {
+        if (typeof expected === 'string' && caught.error && caught.error.message === expected) {
+            throw new TypeError('The "error/message" argument is ambiguous. The error message ' + inspect(expected) + ' is identical to the message.');
+        }
+        if (typeof expected === 'function') {
+            if (typeof expected.prototype !== 'undefined' && caught.error instanceof expected) {
+                passed = true;
+            } else if (isProto(Error, expected)) {
+                passed = false;
+            } else {
+                passed = expected.call({}, caught.error) === true;
+            }
+        } else if (isRegExp(expected)) {
+            passed = expected.test(caught.error);
+            expected = inspect(expected);
+        } else if (expected && typeof expected === 'object') { // Handle validation objects.
+            var keys = Object.keys(expected);
+            // Special handle errors to make sure the name and the message are compared as well.
+            if (expected instanceof Error) {
+                keys.push('name', 'message');
+            } else if (keys.length === 0) {
+                throw new TypeError('`throws` validation object must not be empty');
+            }
+            passed = keys.every(function (key) {
+                if (typeof caught.error[key] === 'string' && isRegExp(expected[key]) && expected[key].test(caught.error[key])) {
+                    return true;
+                }
+                if (key in caught.error && deepEqual(caught.error[key], expected[key], { strict: true })) {
+                    return true;
+                }
+                return false;
+            });
+        }
     }
 
-    this._assert(typeof fn === 'function' && passed, {
+    this._assert(!!passed, {
         message: defined(msg, 'should throw'),
         operator: 'throws',
         actual: caught && caught.error,

package.json

@@ -19,6 +19,7 @@
         "is-regex": "^1.0.5",
         "minimist": "^1.2.0",
         "object-inspect": "^1.7.0",
+        "object.assign": "^4.1.0",
         "resolve": "^1.14.1",
         "resumer": "^0.0.0",
         "string.prototype.trim": "^1.2.1",