Testing strategies, upload QA walkthroughs, and product notes from the Dummy File Generator team.
A composite, illustrative scenario: a .jpg that is really text crashes a thumbnail worker, a too-strict fix blocks valid photos, and a layered check (magic bytes, then a sandboxed decode) resolves both.
Read moreA composite, illustrative scenario showing how three exact-size PDF fixtures (5,242,879 / 5,242,880 / 5,242,881 bytes) can expose silent truncation and vague error messages, plus the checks that catch them.
Read moreWhat changed on Dummy File Generator and how to use it: valid exact-size PDFs, DOCX/ZIP/WebP output, a Chrome extension, ready-made /download test-file pages, an /upload-limits reference, and the earlier magic-byte and scenario tools.
Read moreA fair comparison of downloading hosted sample files, generating files in the browser, and making them with truncate, fallocate, dd or mkfile: exact sizes, format validity, data flow, reproducibility and CI use.
Read moreA test set for image upload pipelines: EXIF orientation, GPS stripping, transparency, CMYK, huge dimensions, animation and size limits. With ImageMagick and exiftool commands to build each input and checks for each output.
Read moreA polyglot is one file that is valid as two formats at once, so it passes a magic-byte check as one type and is read as another. Why formats allow this, how to build a harmless probe for staging, and the defences that actually work.
Read moreOn localhost every upload finishes instantly, so progress bars, cancel buttons and timeouts go untested. How to throttle uploads in DevTools and Playwright, how long a given file should take, and what to check while it runs.
Read moreWorking code for setting files on upload inputs in Playwright, Cypress and Selenium, including hidden inputs, drag-and-drop zones, remote grids, and asserting on what the server actually received.
Read moreA practical setup for building a frontend before the API exists: schema-checked JSON fixtures, Mock Service Worker handlers for every UI state (including slow, huge and failed uploads), and Playwright route mocks for tests.
Read moreHow a browser builds a large file (a typed array, a Blob and an object URL), where the memory goes, why this site generates on the main thread and caps files at 512 MiB, and what to use when you need gigabytes.
Read moreThe extension, the Content-Type header and the magic bytes are three different claims about a file, and only one is hard to fake. How each is produced, server-side checks in Node and Python, the formats that have no signature, and a test matrix.
Read moreHow we keep upload fixtures reproducible without bloating the repository: a naming scheme, a manifest of expected results, and small Node.js helpers that pad JSON and PNG files to exact sizes at test time.
Read moreThe four most common test file formats hit very different code paths. How each is structured, how it behaves when padded to a target size, and the parser bugs each one is good at finding.
Read moreA practical way to turn an upload requirement into a small, complete set of test files: equivalence partitions, boundary values in bytes, a results table, and a k6 script for concurrent uploads.
Read moreGrabbing "some big PDF" from your Downloads folder misses the bugs that matter. Six concrete upload failures, how to reproduce each with a dummy file, and what the fix usually looks like.
Read moreA dummy file is a real, openable file whose contents do not matter but whose type and exact size do. Here is how one is built, how to verify it, and when a real sample is the better choice.
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