implement tests for multipage pdf embedding

tests/pdf_embedding.typ

@@ -0,0 +1,17 @@
+#import "../template/pdf.typ": number_of_pages, embed_full
+
+#let pdfinfo(src, target_pagecount) = {
+  let pdf = read(src, encoding: none);
+  let pagecount = number_of_pages(pdf);
+  [
+    = #src
+    Pagecount: #pagecount
+  ];
+  place(bottom + right, [Starting on next page]);
+  assert(pagecount == target_pagecount);
+  embed_full(pdf);
+}
+
+#pdfinfo("./pdf_embedding_01.pdf", 1)
+#pdfinfo("./pdf_embedding_02.pdf", 2)
+#pdfinfo("./pdf_embedding_03.pdf", 1)