# Building and testing

## Presets and options

Four configure/build presets live in `CMakePresets.json`:

| preset | binaryDir | what it builds |
|---|---|---|
| `linux-debug` | `build/debug` | Debug; tests, examples and all four adapters |
| `linux-release` | `build/release` | Release; `PLOT_BUILD_TESTS=OFF` (so the installed `libplot_core.a` carries none of the test-only counter instrumentation); examples and all four adapters |
| `linux-asan` | `build/asan` | Debug with `PLOT_SANITIZE=address`; tests and all four adapters |
| `linux-coverage` | `build/cov` | the instrumented tree behind `tools/coverage.sh`: `--coverage -O0 -g`, `PLOT_COVERAGE=ON`, tests on, adapters and examples off |

The options (`cmake/plot_options.cmake`) and their defaults:

| option | default | meaning |
|---|---|---|
| `PLOT_BUILD_TESTS` | `ON` | build the test suite (needs EGL) |
| `PLOT_BUILD_EXAMPLES` | `OFF` | build the demos |
| `PLOT_BUILD_GLFW` | `OFF` | build the GLFW adapter and its demo |
| `PLOT_BUILD_IMGUI` | `OFF` | build the Dear ImGui adapter and its demo (ImGui is fetched at configure time) |
| `PLOT_BUILD_QT6` | `OFF` | build the Qt6 adapter and its demo |
| `PLOT_BUILD_GTK4` | `OFF` | build the GTK4 adapter and its demo |
| `PLOT_BUILD_TTF_FONT` | on iff `third_party/stb_truetype.h` exists | build the optional `plot::text::TrueTypeFont` backend |
| `PLOT_INSTALL` | `ON` | generate install/export rules for `find_package(plot)` |
| `PLOT_SANITIZE` | `""` | sanitizer list for `-fsanitize=` (e.g. `address`) |
| `PLOT_COVERAGE` | `OFF` | add the `coverage` target (requires an instrumented tree) |

Adapters and examples are off by default, so the core library and its tests build on a bare
toolchain. Each example is guarded by the adapter target it needs, so
`-DPLOT_BUILD_EXAMPLES=ON` without the matching adapter is a no-op rather than a configure
error.

## Running the suite

```sh
cmake --preset linux-debug
cmake --build build/debug
ctest --test-dir build/debug --output-on-failure
```

ctest registers four tests: `plot_tests` (the test binary), the two header/umbrella build
checks (`plot_headers_self_contained`, `plot_umbrella_covers_public_headers`) and
`plot_umbrella_check`. The `plot_tests` binary itself runs **350 cases** in the `linux-debug`
preset; its harness prints one line per case and a final `350 cases, 0 failed` summary line.
The case counts per file are the `PLOT_TEST(...)` declarations under `tests/` — recount them
(`grep -c '^PLOT_TEST(' tests/test_*.cpp`) after adding or removing cases.

## Install layout

`cmake --install` follows `GNUInstallDirs`, so every path honours the standard cache
variables (`CMAKE_INSTALL_LIBDIR`, `CMAKE_INSTALL_INCLUDEDIR`, …) and their distribution
defaults — plain `lib`, `include` and `share` unless a packager overrides them:

| prefix-relative path | what |
|---|---|
| `lib/` | the `plot_core` archive (and `libplot_core.so` with its version and SONAME symlinks when built with `BUILD_SHARED_LIBS=ON`) |
| `include/plot/` | every public header, including the generated `plot/version.hpp` (`plot::version::major/minor/patch/string` and the `PLOT_VERSION_*` macros) |
| `lib/cmake/plot/` | the CMake package: `plotConfig.cmake`, `plotConfigVersion.cmake` (Compatibility **SameMinorVersion**, so `find_package(plot 0.1 …)` accepts 0.1.x only), `plotTargets.cmake` |
| `lib/pkgconfig/plot.pc` | pkg-config metadata for consumers whose build is not CMake |
| `share/licenses/plot/` | `LICENSE` (MIT) and `licences/OFL-1.1.txt` (the embedded font) |

Adapters that were built and exported install themselves alongside the core (their headers
under `include/<adapter>/`, their targets in the same package).

## Headless demo modes

Each demo supports two environment variables, implemented once and reused:

- `PLOT_DEMO_EXIT_AFTER_MS=<n>` — stop the loop after `n` milliseconds and return. Unset,
  unparsable or not positive means "run until the window is closed". A run with a deadline
  creates its window hidden, so an automated run never flashes a window on a real display,
  and its frame times are not throttled by a vblank.
- `PLOT_DEMO_SCREENSHOT=<path>` — on that final frame, write it as a binary PPM before the
  swap. The GLFW host writes the framebuffer with `Renderer::dump_frame_ppm()`; the ImGui
  demo writes the whole framebuffer, while Qt and GTK write their widget's/area's own
  framebuffer (their toolkits' chrome lives outside it).

That pair is what lets CI run the GUI demos under `xvfb-run` with no display access and no
screen capture (the invocations are in [embedding.md](embedding.md)).

Three demos add env-gated **self-checking** modes. These are verification affordances for
the project's own testing, driven through the real host and its own controllers — they are
not a second implementation of anything, and they exit non-zero if a measured property fails:

| variable | demo | what it drives |
|---|---|---|
| `PLOT_DEMO_FOLLOW=1` | `plot_glfw_demo` | the live-follow sequence: three wheel notches and a pan on a `XFollow::Live` axis, printing the range width, the distance behind the newest sample and the follow state at each step |
| `PLOT_DEMO_REGIONS` (`=hot` to hover a bound) | `plot_glfw_demo` | the direct-manipulation sequence: freeze the view, place a region, pan 100 px with the press outside it, and check the region came along with its width untouched |
| `PLOT_DEMO_SYNC=1` | `plot_multiplot_demo` | the synced-follow check: the three rows hold one range and its right edge keeps tracking the newest sample through a zoom and a pan on different rows |
| `PLOT_DEMO_CROSSHAIR=<row>` | `plot_multiplot_demo` | parks the pointer in a row each frame so a headless screenshot shows the one horizontal line the hovered row draws |

(`plot_glfw_demo` also accepts `PLOT_DEMO_CROSSHAIR=1`, which parks the pointer at the centre
of the data area so the two-line crosshair has ink to measure.)

## Coverage

```sh
tools/coverage.sh                            # from the repository root
cmake --build build/cov --target coverage    # the same thing, through CMake
```

The script configures `build/cov` from the `linux-coverage` preset, builds it, clears the
`.gcda` counters, runs the whole suite, captures `src/**` with `lcov`, renders an HTML report
to `build/cov/html/index.html`, prints the per-file table, and **exits non-zero when a floor
is violated**. It needs `cmake`, `ninja`, `ctest`, `lcov`, `genhtml` and `python3`, and exits
`2` with a message when one is missing.

The floors are enforced by `tools/coverage_floor.py`:

| scope | floor |
|---|---|
| every file under `src/` | **80%** of its instrumented lines |
| `src/` as a whole | **90%** of instrumented lines |

Branch coverage is deliberately off. This page carries no measured totals — a number written
here would be stale the moment `src/` moved, and the report is reproducible: the method, the
per-file table and the floor verdict live in [docs/coverage.md](coverage.md), which
`tools/coverage.sh` rewrites from the very run that measured them. Re-run the command for the
live numbers.

**One thing to know about the coverage preset:** it builds **333 of the 350 cases**. The 17
that are missing are the adapter cases that need an adapter target to exist — 11 in
`test_imgui_widget.cpp` and 6 in `test_glfw_host.cpp` — and the coverage preset turns the
adapters off. The toolkit-free adapter seams still run there: `test_qt_pointer.cpp` (5 cases)
and `test_gtk_input.cpp` (11 cases) compile without Qt or GTK. So the coverage number measures
the library plus its unit suite, not the adapter bodies (which the headless demo runs cover).