fix: don't try to require('diff') for browsers

the sourcemaps crash some front-end transpilers :-(

package.json

@@ -24,6 +24,9 @@
       ]
     }
   },
+  "browser": {
+    "diff": "./lib/diff-stub.js"
+  },
   "dependencies": {
     "diff": "^3.3.0",
     "lodash": "^4.6.1"

src/assertive.js

@@ -69,10 +69,8 @@ let assert;
 // eslint-disable-next-line global-require
 const _ = global._ || require('lodash');
 
-// we can make this optional for browser use
-let jsDiff;
-// eslint-disable-next-line global-require
-try { jsDiff = require('diff'); } catch (err) { /* */ }
+// may be stubbed out for browsers
+const jsDiff = require('diff');
 
 const toString = Object.prototype.toString;
 
@@ -313,7 +311,7 @@ ${red(wrongLooks)}`, explanation);
     if (wrongLooks === rightLooks) {
       message = `deepEqual ${green(rightLooks)} failed on something that\n` +
         'serializes to the same result (likely some function)';
-    } else if (jsDiff) {
+    } else {
       const values = jsDiff.diffJson(actual, expected).map((entry) => {
         let value = entry.value;
         let prefix = '  ';
@@ -326,9 +324,6 @@ ${red(wrongLooks)}`, explanation);
       });
       message =
         `Actual: ${red('-')} Expected: ${green('+')}\n${values.join('\n')}`;
-    } else {
-      message = `Expected: ${green(rightLooks)}\n Actually: ` +
-        `${red(wrongLooks)}`;
     }
 
     throw error(message, explanation);

src/diff-stub.js

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2013, Groupon, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * Neither the name of GROUPON nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+// can't require('diff') properly with browserify, so just fall back on this
+function diffJson(a, b) {
+  return [
+    { removed: true, value: JSON.stringify(a, null, 2) },
+    { added: true, value: JSON.stringify(b, null, 2) },
+  ];
+}
+exports.diffJson = diffJson;