One known-answer case per implemented clause (#6301)

Co-authored-by: eliets2 <287273517+eliets2@users.noreply.github.com>

crates/preflight/tests/known_answers.rs

@@ -0,0 +1,403 @@
+//! What `verify` answers for each clause it implements, pinned as a known answer.
+//!
+//! Each test builds a small file by hand, from the shape the clause describes rather than from
+//! anything this repository saves, so a bug shared between the verifier and the writer cannot make a
+//! case pass. Two things in the file are not hand-written: the output intent profiles come from
+//! `icc::srgb()`, the crate's own sRGB generator, and the encrypted document in the 6.1.3 case is
+//! encrypted by the object layer, because writing an encryption dictionary by hand would restate the
+//! rules under test.
+//!
+//! The clause strings are the verifier's own citations, pinned here as `lib.rs` writes them. They
+//! have not been compared with the text of the profile yet, so a number that does not name the rule
+//! it is attached to is a finding about the verifier and not about this file.
+//!
+//! The positive case expects no issue under the clause and the negative case expects one; both are
+//! asserted by clause string, so a later change that alters an answer fails here first. Cases where
+//! the verifier is known to disagree with the standard are left out on purpose and recorded as gaps
+//! where the change that adds them is reviewed. Nothing here is a conformance claim.
+
+use pdfcraft_cos::{Algorithm, Document, NewEncryption};
+use pdfcraft_preflight::{Level, convert, declared, icc, verify};
+
+/// A document from hand-written objects and extra trailer entries (copied from the crate's unit
+/// tests).
+fn build(objs: &[&str], trailer_extra: &str) -> Document {
+    let mut out = b"%PDF-1.7\n".to_vec();
+    let mut offsets = Vec::new();
+    for (i, o) in objs.iter().enumerate() {
+        offsets.push(out.len());
+        out.extend_from_slice(format!("{} 0 obj\n{o}\nendobj\n", i + 1).as_bytes());
+    }
+    let xref = out.len();
+    out.extend_from_slice(format!("xref\n0 {}\n0000000000 65535 f \n", objs.len() + 1).as_bytes());
+    for o in offsets {
+        out.extend_from_slice(format!("{o:010} 00000 n \n").as_bytes());
+    }
+    out.extend_from_slice(format!("trailer\n<< /Size {} /Root 1 0 R {trailer_extra} >>\nstartxref\n{xref}\n%%EOF\n", objs.len() + 1).as_bytes());
+    Document::open(std::sync::Arc::new(out)).unwrap()
+}
+
+/// The byte-order mark an XMP packet's `xpacket` instruction names.
+const BOM: char = '\u{feff}';
+
+/// The XMP packet identifying a file as `part`/`conformance`, with `title` as its `dc:title`.
+fn xmp(part: u8, conformance: &str, title: Option<&str>) -> String {
+    let title = match title {
+        Some(t) => format!("   <dc:title><rdf:Alt><rdf:li xml:lang=\"x-default\">{t}</rdf:li></rdf:Alt></dc:title>\n"),
+        None => String::new(),
+    };
+    format!(
+        r#"<?xpacket begin="{BOM}" id="W5M0MpCehiHzreSzNTczkc9d"?>
+<x:xmpmeta xmlns:x="adobe:ns:meta/">
+ <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
+  <rdf:Description rdf:about="" xmlns:pdfaid="http://www.aiim.org/pdfa/ns/id/" xmlns:dc="http://purl.org/dc/elements/1.1/">
+   <pdfaid:part>{part}</pdfaid:part>
+   <pdfaid:conformance>{conformance}</pdfaid:conformance>
+{title}  </rdf:Description>
+ </rdf:RDF>
+</x:xmpmeta>
+<?xpacket end="w"?>"#
+    )
+}
+
+/// The XMP packet of a PDF/A-2b file, with `title` as its title when one is given.
+fn a2b_packet(title: Option<&str>) -> String {
+    xmp(2, "B", title)
+}
+
+/// The catalog's `/Metadata` stream object holding `packet`.
+fn xmp_object(packet: &str) -> String {
+    format!("<< /Type /Metadata /Subtype /XML /Length {} >>\nstream\n{packet}\nendstream", packet.len())
+}
+
+/// A content stream object holding `content`.
+fn content(content: &str) -> String {
+    format!("<< /Length {} >>\nstream\n{content}\nendstream", content.len())
+}
+
+/// An ASCII-hex stream object holding `bytes`, with `dict` as its other entries.
+fn hex_stream(dict: &str, bytes: &[u8]) -> String {
+    let hex: String = bytes.iter().map(|b| format!("{b:02X}")).collect();
+    let data = format!("{hex}>");
+    format!("<< /Filter /ASCIIHexDecode {dict} /Length {} >>\nstream\n{data}\nendstream", data.len())
+}
+
+/// A 128-byte ICC header for a four-component profile, with no `/N` so the header decides.
+fn cmyk_profile_header() -> Vec<u8> {
+    let mut header = vec![0u8; 128];
+    header[0..4].copy_from_slice(&128u32.to_be_bytes());
+    header[16..20].copy_from_slice(b"CMYK");
+    header[20..24].copy_from_slice(b"XYZ ");
+    header[36..40].copy_from_slice(b"acsp");
+    header
+}
+
+/// The catalog's `/OutputIntents`: a `GTS_PDFA1` intent naming the profile in object `n`.
+fn output_intent(n: usize) -> String {
+    let condition = "/OutputConditionIdentifier (sRGB IEC61966-2.1)";
+    let intent = format!("<< /Type /OutputIntent /S /GTS_PDFA1 {condition} /DestOutputProfile {n} 0 R >>");
+    format!("/OutputIntents [{intent}]")
+}
+
+/// An embedded font program stream object, compressed with `filter` when one is given. Its bytes
+/// are not read by any rule: a font program is data, not content.
+fn font_program(filter: Option<&str>) -> String {
+    let filter = match filter {
+        Some(filter) => format!("/Filter {filter} "),
+        None => String::new(),
+    };
+    format!("<< /Length1 4 {filter}/Length 4 >>\nstream\nabcd\nendstream")
+}
+
+/// An image XObject that asks to be interpolated, or does not.
+fn image(interpolate: bool) -> String {
+    format!(
+        "<< /Type /XObject /Subtype /Image /Width 1 /Height 1 /ColorSpace /DeviceGray /BitsPerComponent 8 /Interpolate {interpolate} /Length 1 >>\nstream\n\u{0}\nendstream"
+    )
+}
+
+/// A document whose catalog (object 1) carries `catalog_extra` and, when `packet` is given, the
+/// metadata object 3; whose page tree (object 2) holds the single page `page` (object 4); and whose
+/// objects 5 onwards are `more`, which `page` and `catalog_extra` refer to by number. An absent
+/// `packet` leaves object 3 empty. The page must resolve, so a case that loses it fails instead of
+/// passing because no rule ever reached it.
+fn page_document(page: &str, packet: Option<&str>, catalog_extra: &str, more: &[&str], trailer_extra: &str) -> Document {
+    let metadata = match packet {
+        Some(packet) => xmp_object(packet),
+        None => "null".to_owned(),
+    };
+    let catalog = match packet {
+        Some(_) => format!("<< /Type /Catalog /Pages 2 0 R /Metadata 3 0 R {catalog_extra} >>"),
+        None => format!("<< /Type /Catalog /Pages 2 0 R {catalog_extra} >>"),
+    };
+    let pages = "<< /Type /Pages /Kids [4 0 R] /Count 1 /MediaBox [0 0 200 200] >>";
+    let mut objs = vec![catalog.as_str(), pages, metadata.as_str(), page];
+    objs.extend_from_slice(more);
+    let doc = build(&objs, trailer_extra);
+    assert_eq!(pdfcraft_model::pages(&doc).len(), 1, "the page of this case does not resolve");
+    doc
+}
+
+/// Asserts that `verify` reports `clause` for `doc`.
+fn assert_reported(doc: &Document, level: Level, clause: &str) {
+    let issues = verify(doc, level);
+    assert!(issues.iter().any(|i| i.clause == clause), "no {clause} issue in {issues:#?}");
+}
+
+/// Asserts that `verify` reports nothing under `clause` for `doc`.
+fn assert_not_reported(doc: &Document, level: Level, clause: &str) {
+    let found: Vec<_> = verify(doc, level).into_iter().filter(|i| i.clause == clause).collect();
+    assert!(found.is_empty(), "{clause} was reported: {found:#?}");
+}
+
+#[test]
+fn xmp_metadata_is_required_clause_6_6_2_1() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(None);
+    let identified = page_document(page, Some(packet.as_str()), "", &[], "");
+    assert_not_reported(&identified, Level::A2b, "6.6.2.1");
+    assert_eq!(declared(&identified).pdfa, Some((2, "B".into())));
+    let bare = page_document(page, None, "", &[], "");
+    assert_reported(&bare, Level::A2b, "6.6.2.1");
+}
+
+#[test]
+fn the_declared_part_and_conformance_must_be_the_level_clause_6_6_4() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let matching = a2b_packet(None);
+    let doc = page_document(page, Some(matching.as_str()), "", &[], "");
+    assert_not_reported(&doc, Level::A2b, "6.6.4");
+    for (part, conformance) in [(3, "B"), (2, "A")] {
+        let packet = xmp(part, conformance, None);
+        let doc = page_document(page, Some(packet.as_str()), "", &[], "");
+        assert_reported(&doc, Level::A2b, "6.6.4");
+        assert_eq!(declared(&doc).pdfa, Some((part, conformance.to_owned())));
+    }
+}
+
+#[test]
+fn the_xmp_title_must_match_the_information_dictionary_clause_6_6_3() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let info = "/Info << /Title (Report) >>";
+    let matching = a2b_packet(Some("Report"));
+    let doc = page_document(page, Some(matching.as_str()), "", &[], info);
+    assert_not_reported(&doc, Level::A2b, "6.6.3");
+    let differing = a2b_packet(Some("Draft"));
+    let doc = page_document(page, Some(differing.as_str()), "", &[], info);
+    assert_reported(&doc, Level::A2b, "6.6.3");
+}
+
+#[test]
+fn the_trailer_must_not_name_encryption_clause_6_1_3() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(None);
+    let plain = page_document(page, Some(packet.as_str()), "", &[], "");
+    assert_not_reported(&plain, Level::A2b, "6.1.3");
+    // An encrypted file's keys are not written out by hand here, so the /Encrypt dictionary comes
+    // from the object layer; the rule under test only asks whether the trailer names one.
+    let mut encrypted = page_document(page, Some(packet.as_str()), "", &[], "");
+    let params = NewEncryption {
+        algorithm: Algorithm::Aes256,
+        user_password: "",
+        owner_password: "owner",
+        permissions: -4,
+        encrypt_metadata: true,
+        seed: [7; 32],
+    };
+    encrypted.set_encryption(&params).unwrap();
+    assert_reported(&encrypted, Level::A2b, "6.1.3");
+    let report = convert(&mut encrypted, Level::A2b).unwrap();
+    assert!(!report.remaining.iter().any(|i| i.clause == "6.1.3"), "{:#?}", report.remaining);
+}
+
+#[test]
+fn device_colour_needs_an_output_intent_clause_6_2_3() {
+    let page = "<< /Type /Page /Parent 2 0 R /Contents 5 0 R /Resources << >> >>";
+    let packet = a2b_packet(None);
+    let rgb = content("1 0 0 rg 10 10 20 20 re f");
+    let doc = page_document(page, Some(packet.as_str()), "", &[rgb.as_str()], "");
+    assert_reported(&doc, Level::A2b, "6.2.3");
+    let none = content("q Q");
+    let doc = page_document(page, Some(packet.as_str()), "", &[none.as_str()], "");
+    assert_not_reported(&doc, Level::A2b, "6.2.3");
+}
+
+#[test]
+fn device_rgb_needs_an_rgb_output_intent_clause_6_2_4_3() {
+    let page = "<< /Type /Page /Parent 2 0 R /Contents 5 0 R /Resources << >> >>";
+    let packet = a2b_packet(None);
+    let rgb = content("1 0 0 rg 10 10 20 20 re f");
+    let srgb = hex_stream("/N 3", &icc::srgb());
+    let doc = page_document(page, Some(packet.as_str()), &output_intent(6), &[rgb.as_str(), srgb.as_str()], "");
+    assert_not_reported(&doc, Level::A2b, "6.2.4.3");
+    // The intent is there, so the neighbour rule about device colour without one stays quiet.
+    assert_not_reported(&doc, Level::A2b, "6.2.3");
+    let cmyk = hex_stream("", &cmyk_profile_header());
+    let doc = page_document(page, Some(packet.as_str()), &output_intent(6), &[rgb.as_str(), cmyk.as_str()], "");
+    assert_reported(&doc, Level::A2b, "6.2.4.3");
+}
+
+#[test]
+fn the_catalog_must_not_have_additional_actions_clause_6_5_2() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(None);
+    let plain = page_document(page, Some(packet.as_str()), "", &[], "");
+    assert_not_reported(&plain, Level::A2b, "6.5.2");
+    let acting = page_document(page, Some(packet.as_str()), "/AA << /WC << /S /GoTo >> >>", &[], "");
+    assert_reported(&acting, Level::A2b, "6.5.2");
+}
+
+#[test]
+fn the_catalog_must_not_have_document_javascript_clause_6_5_1() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(None);
+    let plain = page_document(page, Some(packet.as_str()), "", &[], "");
+    assert_not_reported(&plain, Level::A2b, "6.5.1");
+    // An empty name tree is enough: an action object here would report the same clause, and this
+    // case is about the catalog's own entry.
+    let tree = "/Names << /JavaScript << /Names [] >> >>";
+    let scripted = page_document(page, Some(packet.as_str()), tree, &[], "");
+    assert_reported(&scripted, Level::A2b, "6.5.1");
+}
+
+#[test]
+fn the_form_must_not_ask_viewers_for_appearances_clause_6_4_1() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(None);
+    let plain = page_document(page, Some(packet.as_str()), "/AcroForm << /Fields [] >>", &[], "");
+    assert_not_reported(&plain, Level::A2b, "6.4.1");
+    let asking = "/AcroForm << /Fields [] /NeedAppearances true >>";
+    let doc = page_document(page, Some(packet.as_str()), asking, &[], "");
+    assert_reported(&doc, Level::A2b, "6.4.1");
+}
+
+#[test]
+fn forbidden_annotation_types_are_reported_clause_6_3_1() {
+    let page = "<< /Type /Page /Parent 2 0 R /Annots [5 0 R] >>";
+    let packet = a2b_packet(None);
+    let link = "<< /Type /Annot /Subtype /Link /Rect [10 10 30 30] /P 4 0 R /F 4 >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[link], "");
+    assert_not_reported(&doc, Level::A2b, "6.3.1");
+    let sound = "<< /Type /Annot /Subtype /Sound /Rect [10 10 30 30] /P 4 0 R /F 4 >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[sound], "");
+    assert_reported(&doc, Level::A2b, "6.3.1");
+}
+
+#[test]
+fn annotations_must_print_and_not_hide_clause_6_3_2() {
+    let page = "<< /Type /Page /Parent 2 0 R /Annots [5 0 R] >>";
+    let packet = a2b_packet(None);
+    let appearance = "<< /Type /XObject /Subtype /Form /BBox [0 0 20 20] /Length 0 >>\nstream\n\nendstream";
+    let printing = "<< /Type /Annot /Subtype /Square /Rect [10 10 30 30] /P 4 0 R /F 4 /AP << /N 6 0 R >> >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[printing, appearance], "");
+    assert_not_reported(&doc, Level::A2b, "6.3.2");
+    let unprinted = "<< /Type /Annot /Subtype /Square /Rect [10 10 30 30] /P 4 0 R /F 0 /AP << /N 6 0 R >> >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[unprinted, appearance], "");
+    assert_reported(&doc, Level::A2b, "6.3.2");
+    let hidden = "<< /Type /Annot /Subtype /Square /Rect [10 10 30 30] /P 4 0 R /F 6 /AP << /N 6 0 R >> >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[hidden, appearance], "");
+    assert_reported(&doc, Level::A2b, "6.3.2");
+}
+
+#[test]
+fn annotations_need_an_appearance_stream_clause_6_3_3() {
+    let page = "<< /Type /Page /Parent 2 0 R /Annots [5 0 R] >>";
+    let packet = a2b_packet(None);
+    let appearance = "<< /Type /XObject /Subtype /Form /BBox [0 0 20 20] /Length 0 >>\nstream\n\nendstream";
+    let with = "<< /Type /Annot /Subtype /Square /Rect [10 10 30 30] /P 4 0 R /F 4 /AP << /N 6 0 R >> >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[with, appearance], "");
+    assert_not_reported(&doc, Level::A2b, "6.3.3");
+    let without = "<< /Type /Annot /Subtype /Square /Rect [10 10 30 30] /P 4 0 R /F 4 >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[without], "");
+    assert_reported(&doc, Level::A2b, "6.3.3");
+}
+
+#[test]
+fn lzw_compressed_streams_are_reported_clause_6_1_7_2() {
+    let page = "<< /Type /Page /Parent 2 0 R /Contents 5 0 R /Resources << /Font << /F1 6 0 R >> >> >>";
+    let packet = a2b_packet(None);
+    let text = content("BT /F1 12 Tf 10 10 Td (Hi) Tj ET");
+    let font = "<< /Type /Font /Subtype /TrueType /BaseFont /Sans /FirstChar 72 /LastChar 105 /Widths [500 500] /FontDescriptor 7 0 R >>";
+    let descriptor = "<< /Type /FontDescriptor /FontName /Sans /Flags 32 /FontFile2 8 0 R >>";
+    let flate = font_program(Some("/FlateDecode"));
+    let doc = page_document(page, Some(packet.as_str()), "", &[text.as_str(), font, descriptor, flate.as_str()], "");
+    assert_not_reported(&doc, Level::A2b, "6.1.7.2");
+    // The neighbour rule holds: the font still reads as embedded.
+    assert_not_reported(&doc, Level::A2b, "6.2.11.4");
+    let lzw = font_program(Some("/LZWDecode"));
+    let doc = page_document(page, Some(packet.as_str()), "", &[text.as_str(), font, descriptor, lzw.as_str()], "");
+    assert_reported(&doc, Level::A2b, "6.1.7.2");
+}
+
+#[test]
+fn streams_must_not_read_external_files_clause_6_1_7_1() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(None);
+    let held = "<< /Length 4 >>\nstream\nabcd\nendstream";
+    let doc = page_document(page, Some(packet.as_str()), "", &[held], "");
+    assert_not_reported(&doc, Level::A2b, "6.1.7.1");
+    // A stream object nothing refers to: the rule looks at every stream in the file.
+    let external = "<< /Length 4 /F (data.bin) >>\nstream\nabcd\nendstream";
+    let doc = page_document(page, Some(packet.as_str()), "", &[external], "");
+    assert_reported(&doc, Level::A2b, "6.1.7.1");
+}
+
+#[test]
+fn images_must_not_be_interpolated_clause_6_2_8() {
+    let page = "<< /Type /Page /Parent 2 0 R /Contents 6 0 R /Resources << /XObject << /Im0 5 0 R >> >> >>";
+    let packet = a2b_packet(None);
+    let drawing = content("q 10 0 0 10 0 0 cm /Im0 Do Q");
+    let smooth = image(true);
+    let doc = page_document(page, Some(packet.as_str()), "", &[smooth.as_str(), drawing.as_str()], "");
+    assert_reported(&doc, Level::A2b, "6.2.8");
+    let crisp = image(false);
+    let doc = page_document(page, Some(packet.as_str()), "", &[crisp.as_str(), drawing.as_str()], "");
+    assert_not_reported(&doc, Level::A2b, "6.2.8");
+}
+
+#[test]
+fn postscript_xobjects_are_reported_clause_6_2_9() {
+    let plain = "<< /Type /Page /Parent 2 0 R /Contents 5 0 R >>";
+    let with = "<< /Type /Page /Parent 2 0 R /Contents 5 0 R /Resources << /XObject << /PS0 6 0 R >> >> >>";
+    let packet = a2b_packet(None);
+    let drawing = content("q Q");
+    let doc = page_document(plain, Some(packet.as_str()), "", &[drawing.as_str()], "");
+    assert_not_reported(&doc, Level::A2b, "6.2.9");
+    let postscript = "<< /Type /XObject /Subtype /PS /Length 0 >>\nstream\n\nendstream";
+    let doc = page_document(with, Some(packet.as_str()), "", &[drawing.as_str(), postscript], "");
+    assert_reported(&doc, Level::A2b, "6.2.9");
+}
+
+#[test]
+fn fonts_must_be_embedded_clause_6_2_11_4() {
+    let page = "<< /Type /Page /Parent 2 0 R /Resources << /Font << /F1 5 0 R >> >> >>";
+    let packet = a2b_packet(None);
+    let embedded = "<< /Type /Font /Subtype /TrueType /BaseFont /Sans /FontDescriptor 6 0 R >>";
+    let descriptor = "<< /Type /FontDescriptor /FontName /Sans /Flags 32 /FontFile2 7 0 R >>";
+    let program = font_program(None);
+    let doc = page_document(page, Some(packet.as_str()), "", &[embedded, descriptor, program.as_str()], "");
+    assert_not_reported(&doc, Level::A2b, "6.2.11.4");
+    let missing = "<< /Type /Font /Subtype /TrueType /BaseFont /Sans >>";
+    let doc = page_document(page, Some(packet.as_str()), "", &[missing], "");
+    assert_reported(&doc, Level::A2b, "6.2.11.4");
+}
+
+/// A file built by hand, apart from its output profile, with everything the verifier asks for: an
+/// XMP packet naming PDF/A-2b with a title that matches the document information, an sRGB output
+/// intent and a blank page. It checks that the rules agree with each other, which is not by itself a
+/// conformance claim.
+#[test]
+fn minimal_document_has_no_verifier_issues() {
+    let page = "<< /Type /Page /Parent 2 0 R >>";
+    let packet = a2b_packet(Some("Report"));
+    let profile = hex_stream("/N 3", &icc::srgb());
+    let info = "/Info << /Title (Report) >>";
+    let mut doc = page_document(page, Some(packet.as_str()), &output_intent(5), &[profile.as_str()], info);
+    let issues = verify(&doc, Level::A2b);
+    assert!(issues.is_empty(), "{issues:#?}");
+    assert_eq!(declared(&doc).pdfa, Some((2, "B".into())));
+    assert_eq!(declared(&doc).output_intents, ["sRGB IEC61966-2.1"]);
+    let report = convert(&mut doc, Level::A2b).unwrap();
+    assert!(report.remaining.is_empty(), "{:#?}", report.remaining);
+    assert_eq!(declared(&doc).pdfa, Some((2, "B".into())));
+}