From fbf5e226ec9194ab67081cb9ecdd5f839cd87c3a Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 9 Aug 2026 14:33:12 +0100
Subject: Check image content type for backslashes

---
 test/images.tests.js | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'test')

diff --git a/test/images.tests.js b/test/images.tests.js
index f308174..5bcf3ba 100644
--- a/test/images.tests.js
+++ b/test/images.tests.js
@@ -110,3 +110,45 @@ test('mammoth.images.imgElement()', {
         });
     }
 });
+
+test("imageFilenameExtension", {
+    "extension is derived from subtype of content type": function() {
+        var image = new documents.Image({
+            contentType: "image/gif"
+        });
+
+        var result = mammoth.images.imageFilenameExtension(image);
+
+        assertThat(result, equalTo("gif"));
+    },
+
+    "data after second slash is ignored": function() {
+        var image = new documents.Image({
+            contentType: "image/gif/jpeg"
+        });
+
+        var result = mammoth.images.imageFilenameExtension(image);
+
+        assertThat(result, equalTo("gif"));
+    },
+
+    "backslashes are treated as forward slashes": function() {
+        var image = new documents.Image({
+            contentType: "image\\gif\\..\\"
+        });
+
+        var result = mammoth.images.imageFilenameExtension(image);
+
+        assertThat(result, equalTo("gif"));
+    },
+
+    "when there is no subtype then null is returned": function() {
+        var image = new documents.Image({
+            contentType: "image"
+        });
+
+        var result = mammoth.images.imageFilenameExtension(image);
+
+        assertThat(result, equalTo(undefined));
+    }
+});
-- 
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