From 4f55ff61bacd74378fe959644d857e5ec46043f3 Mon Sep 17 00:00:00 2001
From: Morten Nilsen <moni@dips.no>
Date: Tue, 14 Jul 2026 09:24:57 +0200
Subject: [PATCH] Normalize Dublin Core <dc:date> in PdfNormalizer

PdfNormalizer zeroed the xmp:CreateDate/ModifyDate/MetadataDate elements but not the Dublin Core <dc:date> element. Apache FOP writes the render timestamp into <dc:date>, so the #pdf snapshot target (added in #516) was non-deterministic for FOP-produced PDFs while the sibling dates were neutralized. Adds <dc:date> to the normalized set plus a focused test.
---
 src/Tests/PdfNormalizerTests.cs    | 10 ++++++++++
 src/Verify.DocNet/PdfNormalizer.cs |  1 +
 2 files changed, 11 insertions(+)

diff --git a/src/Tests/PdfNormalizerTests.cs b/src/Tests/PdfNormalizerTests.cs
index c57ed74..37aa347 100644
--- a/src/Tests/PdfNormalizerTests.cs
+++ b/src/Tests/PdfNormalizerTests.cs
@@ -28,6 +28,16 @@ public void NeutralizesVolatileValues()
         Assert.That(Normalize(input), Is.EqualTo(expected));
     }
 
+    [Test]
+    public void NeutralizesDublinCoreDate()
+    {
+        // Some producers (for example Apache FOP) write the render time into the Dublin Core
+        // <dc:date> element, a volatile per-render value like its xmp:* date siblings.
+        var input = "<dc:date>2024-01-15T09:30:00+05:30</dc:date>";
+        var expected = "<dc:date>0000-00-00T00:00:00+00:00</dc:date>";
+        Assert.That(Normalize(input), Is.EqualTo(expected));
+    }
+
     [Test]
     public void CollapsesDifferingValuesToTheSameOutput()
     {
diff --git a/src/Verify.DocNet/PdfNormalizer.cs b/src/Verify.DocNet/PdfNormalizer.cs
index d85d37c..69a3a29 100644
--- a/src/Verify.DocNet/PdfNormalizer.cs
+++ b/src/Verify.DocNet/PdfNormalizer.cs
@@ -42,6 +42,7 @@ public static void Normalize(byte[] data)
         ZeroXmpElement(data, "<xmp:CreateDate"u8, Fill.Digits);
         ZeroXmpElement(data, "<xmp:ModifyDate"u8, Fill.Digits);
         ZeroXmpElement(data, "<xmp:MetadataDate"u8, Fill.Digits);
+        ZeroXmpElement(data, "<dc:date"u8, Fill.Digits);
 
         // XMP per-generation identifiers.
         ZeroXmpElement(data, "<xmpMM:DocumentID"u8, Fill.All);