Have qpdf-test-compare handle certain /ID differences

Rationale is in comments in the code. Deterministic ID tests
explicitly do not use this tool.

5 files changed, 9 insertions, 0 deletions

diff --git a/compare-for-test/qtest/compare.test b/compare-for-test/qtest/compare.test
index 48625cf3..bcf6b788 100644
--- a/compare-for-test/qtest/compare.test
+++ b/compare-for-test/qtest/compare.test
@@ -52,6 +52,7 @@ my @diff = (
     ["diff-data-unc.pdf", "5,0: stream data differs"],
     ["diff-stream-dict.pdf", "4,0: stream dictionaries differ"],
     ["diff-object-type.pdf", "6,0: different types"],
+    ["diff-id.pdf", "trailer: object contents differ"],
     );
 $n_tests += 2 * scalar(@diff);
 
@@ -90,4 +91,12 @@ $td->runtest("compare object stream files (same)",
              {$td->COMMAND => "env QPDF_COMPARE_WHY=1 qpdf-test-compare ostream1.pdf ostream2.pdf"},
              {$td->FILE => "ostream2.pdf", $td->EXIT_STATUS => 0});
 
+$n_tests += 2;
+$td->runtest("files identical except /ID[1]",
+             {$td->COMMAND => "env QPDF_COMPARE_WHY=1 qpdf-test-compare zlib.pdf zlib-new-id.pdf"},
+             {$td->FILE => "zlib-new-id.pdf", $td->EXIT_STATUS => 0});
+$td->runtest("/ID[0] = /ID[1]",
+             {$td->COMMAND => "env QPDF_COMPARE_WHY=1 qpdf-test-compare zlib-new-id1.pdf zlib-new-id2.pdf"},
+             {$td->FILE => "zlib-new-id2.pdf", $td->EXIT_STATUS => 0});
+
 $td->report($n_tests);
diff --git a/compare-for-test/qtest/compare/diff-id.pdf b/compare-for-test/qtest/compare/diff-id.pdf
new file mode 100644
index 00000000..58df0db7
--- /dev/null
+++ b/compare-for-test/qtest/compare/diff-id.pdf
diff --git a/compare-for-test/qtest/compare/zlib-new-id.pdf b/compare-for-test/qtest/compare/zlib-new-id.pdf
new file mode 100644
index 00000000..8618f369
--- /dev/null
+++ b/compare-for-test/qtest/compare/zlib-new-id.pdf
diff --git a/compare-for-test/qtest/compare/zlib-new-id1.pdf b/compare-for-test/qtest/compare/zlib-new-id1.pdf
new file mode 100644
index 00000000..5dd7a823
--- /dev/null
+++ b/compare-for-test/qtest/compare/zlib-new-id1.pdf
diff --git a/compare-for-test/qtest/compare/zlib-new-id2.pdf b/compare-for-test/qtest/compare/zlib-new-id2.pdf
new file mode 100644
index 00000000..1dd13b89
--- /dev/null
+++ b/compare-for-test/qtest/compare/zlib-new-id2.pdf