fix: Wonder Ink prints without crashing, and prints worksheets at all
Little Waders, 0.2.2: SIGSEGV in QPrinter::resolution() every time a teacher confirmed a print job. QWebEngineView.print() keeps the raw QPrinter pointer and returns; Qt's didPrintPage() reads printer->resolution() once Chromium has rendered the page, and by then PyQt had deleted the printer, which print_view() held only as a local. Reproduced in the lab with the 0.2.2 code, same backtrace, no job. Keeping the printer alive fixed the crash and was measured, and Qt's path was still not a print path: a worksheet PDF tab printed as one blank page, a lesson went as 24.6 MB of 300 dpi pictures with no text, and a queue refusing jobs was reported as printed. Print is now: make a PDF (a worksheet already is one; a lesson page is printToPdf'd onto the printer's own paper; an inline PDF is downloaded and opened as a worksheet), show it in a preview with printer, pages, copies and colour, and hand it to CUPS with lp — Chrome's route in the same rooms. Nothing asynchronous holds a printer. Black and white uses the driver's ColorModel=Grayscale, because Elmer's generic PCL 6 driver ignores print-color-mode. An exception escaping any slot no longer aborts Wonder Ink: PyQt6's default is to kill the process, and it is now logged instead. tests/test-classroom-printing.sh: 50 checks. tools/lab/wonderink-print- check: 39 checks over 13 scenarios in the lab, against a queue built from Elmer's PPD, judged by what CUPS received. Not yet on paper. Co-Authored-By: Claude Opus 5.5 <[email protected]>
This commit is contained in:
ekklesia
co-authored by
Claude Opus 5.5
Claude Opus 5.5
parent
690ef95aff
commit
10433b850d
Executable
+204
@@ -0,0 +1,204 @@
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#!/bin/bash
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# Wonder Ink's printing: which printers, which options, what is sent.
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#
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# CUPS is not on the development host, so lpstat, lpoptions, lp and
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# pdfinfo are stand-ins that answer with the output the real ones gave in
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# the lab — Elmer's own PPD options included. Whether a job really goes
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# through Elmer's filters is tools/lab/wonderink-print-check's question.
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set -uo pipefail
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ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
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WORK="$(mktemp -d)"
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trap 'rm -rf "$WORK"' EXIT
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mkdir -p "$WORK/bin"
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cat > "$WORK/bin/lpstat" <<EOF
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#!/bin/bash
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[[ -f "$WORK/cups-down" ]] && { echo "lpstat: Scheduler is not running." >&2; exit 1; }
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case "\$1" in
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-e) cat "$WORK/printers" 2>/dev/null ;;
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-d) cat "$WORK/default" 2>/dev/null || echo "no system default destination" ;;
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esac
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EOF
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# lpoptions -p NAME -l, as the real one printed it for Elmer's PPD.
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cat > "$WORK/bin/lpoptions" <<EOF
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#!/bin/bash
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cat "$WORK/options-\$2" 2>/dev/null
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EOF
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cat > "$WORK/bin/lp" <<EOF
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#!/bin/bash
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printf '%s\n' "\$@" > "$WORK/lp-args"
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if [[ -f "$WORK/lp-refuses" ]]; then
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echo 'lp: Destination "Elmer" is not accepting jobs.' >&2
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exit 1
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fi
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echo "request id is Elmer-42 (1 file(s))"
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EOF
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cat > "$WORK/bin/pdfinfo" <<'EOF'
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#!/bin/bash
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[[ "$(head -c 5 "$1" 2>/dev/null)" == "%PDF-" ]] || { echo "Syntax Error" >&2; exit 1; }
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echo "Producer: test"
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echo "Pages: $(grep -c '^page' "$1")"
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EOF
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chmod +x "$WORK"/bin/*
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printf 'Elmer\n' > "$WORK/printers"
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echo "system default destination: Elmer" > "$WORK/default"
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cat > "$WORK/options-Elmer" <<'EOF'
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PrintoutMode/Print Quality: Draft Draft.Gray *Normal Normal.Gray High High.Gray
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PageSize/Page Size: Custom.WIDTHxHEIGHT *Letter A4 11x17 A3 A5 B5 Env10 EnvC5 EnvDL EnvISOB5 EnvMonarch Executive Legal
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Duplex/Double-Sided Printing: DuplexNoTumble DuplexTumble *None
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ColorModel/Color Mode: FromPrintoutMode *Color Grayscale
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PrinterResolution/Resolution: *FromPrintoutMode 300x300dpi 600x600dpi 1200x600dpi 1200x1200dpi
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EOF
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cat > "$WORK/options-Office" <<'EOF'
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PageSize/Media Size: Letter *A4 Legal
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EOF
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PATH="$WORK/bin:$PATH" WORK="$WORK" PYTHONPATH="$ROOT/lib" python3 - "$ROOT" <<'PY'
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import os
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import re
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import sys
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from pathlib import Path
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import classroom_printing as printing
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root = Path(sys.argv[1])
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work = Path(os.environ["WORK"])
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passed = failed = 0
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def check(label, condition, detail=""):
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global passed, failed
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if condition:
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print(f" ok {label}")
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passed += 1
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else:
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print(f" FAIL {label}")
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if detail:
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print(f" {detail}")
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failed += 1
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def lp_args():
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return (work / "lp-args").read_text().splitlines()
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print("1. which printers a teacher is offered")
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check("Elmer, and Elmer is the default", printing.printers() == (["Elmer"], "Elmer"))
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(work / "printers").write_text("Elmer\nOffice\n")
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(work / "default").write_text("system default destination: Office\n")
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check("the system default is preselected, whichever it is",
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printing.printers() == (["Elmer", "Office"], "Office"))
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(work / "default").write_text("no system default destination\n")
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check("with no default, the first printer",
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printing.printers() == (["Elmer", "Office"], "Elmer"))
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(work / "default").write_text("system default destination: Gone\n")
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check("a default that is not in the list is not offered",
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printing.printers() == (["Elmer", "Office"], "Elmer"))
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(work / "printers").write_text("")
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check("no printers at all is an empty list, not an error",
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printing.printers() == ([], None))
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(work / "cups-down").touch()
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check("and so is CUPS not running", printing.printers() == ([], None))
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(work / "cups-down").unlink()
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(work / "printers").write_text("Elmer\n")
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(work / "default").write_text("system default destination: Elmer\n")
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print()
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print("2. what each printer's driver offers")
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elmer = printing.options("Elmer")
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check("Elmer's paper is Letter", elmer["paper"] == "Letter", elmer)
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# Measured: this driver ignores print-color-mode and prints in colour.
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check("black and white is asked for in the driver's own terms",
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elmer["gray"] == ("ColorModel", "Grayscale"), elmer)
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office = printing.options("Office")
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check("an A4 printer is A4", office["paper"] == "A4", office)
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check("a printer with no grey choice offers none", office["gray"] is None, office)
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unknown = printing.options("Nobody")
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check("a printer that says nothing is Letter, colour only",
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unknown == {"paper": "Letter", "gray": None}, unknown)
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print()
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print("3. a teacher's page list")
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for text, expected in (("", None), ("all", None), (" ", None), ("2", "2"),
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("1-3", "1-3"), ("1, 3, 5-6", "1,3,5-6"), ("3-3", "3"),
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("1 - 2", "1-2"), ("6", "6")):
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try:
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got = printing.parse_pages(text, 6)
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except ValueError as error:
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got = f"refused: {error}"
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check(f"{text!r} is {expected!r}", got == expected, got)
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for text in ("7", "0", "3-1", "1-9", "one", "1;lp -d x", "-2", "1--2", "2,", "1.5"):
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try:
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printing.parse_pages(text, 6)
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check(f"{text!r} is refused", False)
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except ValueError as error:
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check(f"{text!r} is refused, and says why: {error}", bool(str(error)))
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print()
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print("4. what is handed to CUPS")
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pdf = work / "Colour the Ark.pdf"
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pdf.write_text("%PDF-1.4\npage\npage\n")
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check("a PDF with two pages has two", printing.page_count(pdf) == 2)
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check("something that is not a PDF has none",
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printing.page_count(work / "printers") == 0)
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ok, answer = printing.submit(pdf, "Elmer")
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args = lp_args()
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check("a job is accepted, with its id", (ok, answer) == (True, "Elmer-42"), answer)
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check("to Elmer, one copy, named for the lesson",
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args[:6] == ["-d", "Elmer", "-n", "1", "-t", "Wonder Ink"], args)
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check("the file comes after --, so no name can be read as an option",
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args[-2:] == ["--", str(pdf)], args)
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check("and nothing else is asked for", "-P" not in args and "-o" not in args, args)
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printing.submit(pdf, "Elmer", copies=3, pages="2-3", gray=("ColorModel", "Grayscale"),
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title="Noah")
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args = lp_args()
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check("copies, pages and black and white arrive as lp options",
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args[args.index("-n") + 1] == "3"
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and args[args.index("-P") + 1] == "2-3"
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and args[args.index("-o") + 1] == "ColorModel=Grayscale"
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and args[args.index("-t") + 1] == "Noah", args)
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printing.submit(pdf, "Elmer", copies=500)
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check(f"copies are capped at {printing.MAX_COPIES}",
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lp_args()[lp_args().index("-n") + 1] == str(printing.MAX_COPIES))
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printing.submit(pdf, "Elmer", copies=0)
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check("and never fewer than one", lp_args()[lp_args().index("-n") + 1] == "1")
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(work / "lp-refuses").touch()
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ok, answer = printing.submit(pdf, "Elmer")
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check("a refused job is a failure, in CUPS's own words",
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not ok and answer == 'Destination "Elmer" is not accepting jobs.', answer)
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print()
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print("5. Wonder Ink prints through this, and only this")
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ink = (root / "scripts/classroom-wonderink").read_text()
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code = "\n".join(line for line in ink.splitlines() if not line.lstrip().startswith("#"))
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# The 0.2.2 crash, and the blank worksheet, both came from Qt's print path.
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check("no QPrinter", "QPrinter(" not in code and "QPrintDialog" not in code)
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check("no QWebEngineView.print()", not re.search(r"\bview\.print\(", code))
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check("a lesson page becomes a PDF by printToPdf", "printToPdf(" in code)
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check("which is given up on if the engine never answers",
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"PREPARE_TIMEOUT_MS" in code and "self._timer.start(PREPARE_TIMEOUT_MS)" in code)
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check("the preview submits with classroom_printing.submit",
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"classroom_printing.submit(" in code)
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check("there is no file chooser in it", "QFileDialog" not in code)
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check("a worksheet tab is printed from its file",
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"self._pdf_views[view] = resolved" in code)
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check("an inline PDF is fetched as a file first", "view.page().download(view.url())" in code)
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check("an exception in a handler is logged, not fatal",
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"sys.excepthook = keep_going" in code)
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check("the module is packaged",
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"lib/classroom_printing.py" in (root / "tools/build-release.sh").read_text())
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print()
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print(f"{passed} passed, {failed} failed")
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sys.exit(1 if failed else 0)
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PY
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@@ -342,8 +342,11 @@ check("local documents may not read other local documents",
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"LocalContentCanAccessFileUrls, False" in wonderink)
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check("nor reach the network",
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"LocalContentCanAccessRemoteUrls, False" in wonderink)
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check("there is no file chooser behind the print dialog",
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"PrintDialogOption.PrintToFile, False" in wonderink)
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# Qt's print dialog has a Print to File path with a "..." chooser behind
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# it. Wonder Ink no longer uses that dialog: its preview offers CUPS
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# printers and nothing else, and no file dialog exists anywhere in it.
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check("there is no file chooser behind printing",
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"QFileDialog" not in wonderink and "QPrintDialog" not in wonderink)
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check("nothing downloaded is executed",
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"subprocess" not in wonderink.split("def notify")[0]
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and "QDesktopServices" not in wonderink
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@@ -374,8 +377,12 @@ check("the Present-view autoplay fix is still there",
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"PlaybackRequiresUserGesture, False" in wonderink)
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check("fullscreen still returns to a maximised window",
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"WindowFullScreen" in wonderink)
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# One text box exists, and it is the print preview's page range. Anywhere
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# else a text box in this window is an address bar.
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preview = wonderink[wonderink.index("class PrintPreview"):wonderink.index("\ndef notify")]
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check("still no new-tab button or address bar",
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"setCornerWidget" not in wonderink and "QLineEdit" not in wonderink)
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"setCornerWidget" not in wonderink
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and wonderink.count("QLineEdit(") == 1 and "QLineEdit(" in preview)
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print()
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print("7b. the disc player is decided before a session starts")
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Reference in New Issue
Block a user