What's new

fucini-coverage — Coverage Studio on the command line, free

The reader behind the VS Code and Visual Studio editions now runs where an editor is not: npm install -g fucini-coverage puts it on Windows, Linux, WSL and macOS. fucini-coverage check is a gate for a pipeline — lines, branches, functions, MC/DC, conditions, the lines a branch changed against origin/main — and ends with exit code 1 below a threshold; export writes the run as CSV, Markdown, LCOV, Cobertura or SARIF; report writes the HTML report, badge the badge, compare what moved against the last green run, and mcp serves the six tools an AI agent can ask. Twenty-seven formats in, merged as the editors merge them, the same numbers to the digit.

It reads the settings file the Visual Studio edition reads, fucini-coverage.json, with the keys of the VS Code settings, so a team sets its thresholds once and every edition and every pipeline judges by them. Every command documents itself: fucini-coverage help check. It is free, and it ships with 2.2026.0 build 1 of both editions — see fucini-coverage on npm and the download page.

Screenshot pending — add assets/img/cli-demo.gif (see SCREENSHOTS.md).

Coverage Studio 2.2026.0 for VS Code and for Visual Studio — the coverage on screen, for AI agents

An agent that writes tests could run them and read a percentage; it could not ask what the editor knows. From 2.2026.0 it can: six tools answer which lines of a function never ran, which side of a branch was not taken, which tests ran a line, whether a diff is covered and what moved since the last run — from the run that is loaded, with the same exclusions and the same numbers as on screen. VS Code's own agent has them with nothing to set up; every agent that speaks MCP reaches them through a server the editor runs when you turn it on, on this machine only and behind a token of your own. The user guide says how.

Both editions now carry the same version, and with it everything since 1.2026.7: a line that a failing test ran is marked, Run Tests Affected by My Changes… runs only the tests a change touches, a gate on new code stands beside the gates on the whole run, exclusions can say why, Show Minimal Test Set… finds the fewest tests that still run every line, GCC 14's condition coverage is shown line by line, Run This Test with Coverage reads Go and Rust, new code can be counted by author and by date, a CI artifact that is a zip is opened, Run App with Coverage… measures what a person reaches, and Run Mutation Tests Here asks whether a test would notice. A .NET report now shows its branch coverage, which Coverlet's spelling had hidden: those numbers move. In Visual Studio a subscription's plan now decides what it decides in VS Code. Every step is in the changelog, and both builds are on the download page.

Coverage Studio 1.2026.7 for VS Code and 1.2026.6 for Visual Studio — which tests ran a line, coverage after every save, and a CI baseline

This release adds ten features to both editions. Coverage Studio can now say which tests ran a line and open them, run the tests that cover a file each time it is saved, run the one test under the caret with coverage, and hold every load against the report your main branch's build publishes. What should not count can be taken out from the tree, by namespace or attribute, or where the code is; a .NET run can be read by namespace, class and method; the tree has a search box that also takes < 80%; and a coverage session adds up the runs of several test suites until you end it. In Visual Studio, Run Native Project with Coverage runs the startup C++ project under clang-cl's instrumentation. The user guide has a section on each.

Among the fixes: a test run's report no longer carries your user and machine name, a header of macros no longer shows as a file at 100%, an MC/DC build's branch figure matches llvm-cov report, and five report formats that were refused as unsupported are recognised. Everything is in the changelog, and both builds are on the download page.

Coverage Studio 1.2026.6 for VS Code and 1.2026.5 for Visual Studio — a wildcard in a full path, and two reports recognised again

A build that writes its reports under a folder of its own — build/coverage-merged/*.lcov.info, one per module — can now be named in coverageFile.paths with a wildcard in a full path, in VS Code as in Visual Studio, and both editions watch the folders such an entry names: the report of the next build loads the moment it lands, whether or not one was there when the project opened. The user guide has the shapes an entry can take.

Two reports were refused as unsupported and are read again: an llvm-cov JSON export whose first file record was long enough to push everything recognisable past the inspected head, and a gcov --json-format file of a dozen functions, which lists them before its lines. Everything is in the changelog, and both builds are on the download page.

Coverage Studio 1.2026.5 for VS Code and 1.2026.4 for Visual Studio — two reports, one answer

When two reports measure the same code on purpose — the same sources built by clang and by GCC, or unit and integration tests of one build — the newest no longer has to win. Choose, per file, which report speaks for it, or combine them: agree counts a line covered only where every report ran it and marks the lines they disagree on in teal, union where any did. Right-click a file in the Coverage view and pick Choose Coverage Source...; the user guide says when to use which, and the demo has a clang-and-GCC sample to try it on.

Both editions also paint covered lines green in a new red-amber-green gutter mode, let you set the heatmap's shades with a live preview, and put the same number on the status bar as on the card it opens. Everything is in the changelog, and both builds are on the download page.

Coverage Studio for Visual Studio 1.2026.2 — every test run, every report, and what moved; and VS Code 1.2026.3

One day after its first release, the Visual Studio edition has what subscribers use most in VS Code: coverage after every Test Explorer run, without hooking Test Explorer; Run Tests with Coverage; the triangles for what moved since the last run, history and diff coverage; Check Coverage Thresholds with the findings in the Error List; the annotated source in a window of its own, the HTML reports, the eight exports and the badge; risk hotspots and row filters; and a fucini-coverage.json beside the solution, for a team that would rather not keep a .vscode folder. The changelog has every item, and the user guide's In Visual Studio boxes say where each one is.

VS Code 1.2026.3 brings the two things new in both editions — risk hotspots under the tree, the functions where complex code meets little coverage, and a filter beside the sort for the files with gaps, the untested ones or those changed since the last run — and three for .NET: dotnet test without a Coverlet package, generated and designer files left out of every total, and a failed run that keeps the last good coverage on screen. Both are on the download page.

Fucini DevOps Studio: all of Coverage Studio's coverage on the build, as a free extension

Azure DevOps shows coverage on a build today, but only as far as its own format goes: lines, and branches as a percentage. Fucini DevOps Studio will put the whole of what Coverage Studio reads on the build instead — every one of the 25 formats, for every language, with MC/DC, conditions, regions, the composite score, the CRAP score and the gates — as a Coverage tab on the pipeline that produced it, with the same numbers, to the digit, that the editor shows. The same reader, in the third place it is needed.

Updated 3 October: it will be free — the whole extension, on Azure DevOps Services and on Azure DevOps Server, and there will be no paid edition. Announced, not released — subscribe above to hear when it ships.

Coverage Studio for Visual Studio is out — Community, Professional and Enterprise, 2022 and 2026

The same reader, in the other IDE: download it, open a solution or a folder, and the report your build already wrote is on the code — on Visual Studio 2022 Community and Professional too, which have no coverage of their own. It is included with every paid plan; a machine where Coverage Studio for VS Code is activated needs no key of its own, and anywhere else Tools → Coverage Studio → Licence… takes your subscription code. The getting started page walks both editors through the same six steps, the user guide says where the two differ, and the changelog what this first release holds.

With it, VS Code 1.2026.2: the same six steps as a walkthrough on the Welcome page, and the install id left where the Visual Studio edition reads it, so one activation covers both. And a change to the terms: a refund now ends the subscription it paid for at once, one refund per customer — the refund policy has the details.

A seventh on the road ahead: Coverage Studio for Visual Studio

Coverage Studio is coming to Visual Studio — Community, Professional and Enterprise, 2022 and 2026 — with the same reader inside, so the same report gives the same numbers, to the digit, in both editors. It matters most where Visual Studio itself offers nothing: in Visual Studio 2022, code coverage is an Enterprise feature, and a C++ or C# team on Community or Professional has never seen coverage in that IDE at all, whatever their build already writes. It will be included with a Coverage Studio subscription at no extra cost, on the machine you already use it on. Read what it does, and what it will not do.

Announced, not released: it is being tested on both versions of Visual Studio before it is offered for download. Subscribe above to hear when it ships.

The road ahead: six products announced, each with a page of its own

Coverage Studio is no longer the only thing on fucini.software. Announced today, none of it released yet: FuciniLog, a small log collector for Windows hosts and embedded targets with end-to-end encryption; Fucini Beacon, zero-configuration discovery that lets a device announce who it is before anyone has given it an address; Fucini DevOps Studio, bringing coverage, wiki styling and branch creation to Azure DevOps; FuciniUML for VS Code; Fucini Running Coach; and Fucini Puzzle Solver.

Each has a page with what it is, what it runs on and — for FuciniLog — the standards it adopts and what is open source. If one of these would decide something for you, say so through the contact page; that is how the order gets decided. Subscribe above to hear when each one ships.

Eleven new formats: Go, Ada, Swift, and whatever your build already writes

Coverage Studio read six formats two weeks ago; it reads seventeen now. Go’s coverage.out, Clover for PHP, OpenCover for .NET, coverage.py’s own JSON and gcov/gcovr JSON all load directly — no conversion step, and no metric thrown away on the way in.

Then the tools safety teams own: GNATcoverage XML brings Ada in at last, BullseyeCoverage and Visual Studio .coveragexml cover the commercial C/C++ and .NET toolchains, and SonarQube generic coverage is the escape hatch for anything else. Swift and Objective-C arrive through Xcode’s own xccov report — percentages and per-function counts, but no per-line data, so gutters stay empty there by design.

Coveralls JSON rounds it off, any supported format may now arrive gzipped, and copy-paste recipes per language are on the Coverage Recipes page.

Introducing Fucini Coverage Studio Community — free, forever

Instead of a hard stop once the evaluation trial ends, every install now settles into a permanent, free Community tier: every feature except MC/DC, a light monthly taste of the Full HTML Report and the persistent Annotated Source view, and generous daily caps on a handful of automatable actions — everything else unlimited.

Want everything unlocked, MC/DC included, without paying? Run "Fucini Coverage: Unlock Full Features" from the Command Palette and trade detailed usage telemetry for a full, unrestricted grant — reversible any time.

Community is also now its own dedicated, permanently-free listing — see the download page to grab it directly.

Team plans: Pro Plus, Business, and Enterprise

These three plans now share a "seat pool" — one company code covering a fixed number of devices — instead of a separate key per machine. A seat that's gone quiet for a while frees itself up automatically for the next person who needs it, and a background check-in keeps everyone's grant current without anyone having to re-request a key by hand.

See the full plan breakdown on the pricing page.

Referral program is live

Earn 20% of what anyone you refer pays, for their first 12 months. Full worked examples on the referral page.