Add custom validate-docx.sh script.

This checks files other than document.xml in a docx container.
Thanks to @edwintorok.

Makefile

@@ -239,7 +239,7 @@ validate-docx-golden-tests: ## validate docx golden tests against schema
 	which xmllint || ("xmllint is required" && exit 1)
 	test -d ./docx-validator || \
 		git clone https://github.com/devoidfury/docx-validator
-	cd docx-validator && for f in ../test/docx/golden/*.docx; do ./validate $$f || exit 1 ; done
+	sh ./tools/validate-docx.sh test/docx/golden/*.docx
 .PHONY: validate-docx-golden-tests
 
 validate-epub: ## generate an epub and validate it with epubcheck

tools/validate-docx.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# Modified by edwintorok from https://github.com/devoidfury/docx-validator
+# to look at more files than just document.xml.
+# Further modified by jgm for portability.
+tmpdir=$(mktemp -d)
+errors=0
+for file in "$@"; do
+  echo "*** Checking $file"
+  rm -rf "$tmpdir"
+  unzip -q -o -j "$file" -d "$tmpdir"
+  for i in comments document fontTable footnotes numbering settings styles theme1 webSettings; do
+    xmllint --format "$tmpdir/${i}.xml" > "$tmpdir/${i}-pretty.xml"
+  done
+  XSD="./docx-validator/schemas/microsoft/wml-2010.xsd"
+  for i in "$tmpdir"/*-pretty.xml; do
+    xmllint -noout -nonet \
+      -schema "${XSD}" \
+      "${i}" 2>&1 || errors=$((errors + 1))
+  done
+done
+exit $errors