1 files changed, 38 insertions, 0 deletions
diff --git a/packages/markdown/marked/test/helpers/html-differ.js b/packages/markdown/marked/test/helpers/html-differ.js
new file mode 100644
index 00000000..44052be4
--- /dev/null
+++ b/packages/markdown/marked/test/helpers/html-differ.js
@@ -0,0 +1,38 @@
+const HtmlDiffer = require('@markedjs/html-differ').HtmlDiffer;
+const htmlDiffer = new HtmlDiffer({ignoreSelfClosingSlash: true});
+
+module.exports = {
+  isEqual: htmlDiffer.isEqual.bind(htmlDiffer),
+  firstDiff: (actual, expected, padding) => {
+    padding = padding || 30;
+    const result = htmlDiffer
+      .diffHtml(actual, expected)
+      .reduce((obj, diff) => {
+        if (diff.added) {
+          if (obj.firstIndex === null) {
+            obj.firstIndex = obj.expected.length;
+          }
+          obj.expected += diff.value;
+        } else if (diff.removed) {
+          if (obj.firstIndex === null) {
+            obj.firstIndex = obj.actual.length;
+          }
+          obj.actual += diff.value;
+        } else {
+          obj.actual += diff.value;
+          obj.expected += diff.value;
+        }
+
+        return obj;
+      }, {
+        firstIndex: null,
+        actual: '',
+        expected: ''
+      });
+
+    return {
+      actual: result.actual.substring(result.firstIndex - padding, result.firstIndex + padding),
+      expected: result.expected.substring(result.firstIndex - padding, result.firstIndex + padding)
+    };
+  }
+};