edgefirst-tensor 0.23.0

# edgefirst-tensor Testing

## Test Layout

```
crates/tensor/
├── src/
│   ├── lib.rs           # Doc-tests on Tensor<T> public API
│   ├── dma.rs           # DMA backend unit tests (Linux-only)
│   ├── shm.rs           # POSIX shared-memory backend unit tests
│   ├── mem.rs           # Heap backend unit tests
│   ├── pbo.rs           # PboTensor + WeakSender behavior
│   ├── tensor_dyn.rs    # TensorDyn metadata, multi-plane, format/stride checks
│   └── format.rs        # PixelFormat + DType compatibility
└── benches/
    └── tensor_benchmark.rs   # Allocation + map/unmap throughput
```

There is no `tests/` directory; per-backend coverage lives in the source
files alongside the implementation.

## Running Tests

All `cargo test` invocations below pass `-- --test-threads=1` per the
workspace single-threaded rule
([root TESTING.md § Single-threaded execution](https://github.com/EdgeFirstAI/hal/blob/main/TESTING.md#single-threaded-execution)).

```bash
# All tensor tests on the host
cargo test -p edgefirst-tensor -- --test-threads=1

# Heap-only (skips DMA tests when DMA-heap permissions are missing)
EDGEFIRST_TENSOR_FORCE_MEM=1 cargo test -p edgefirst-tensor -- --test-threads=1

# Doc-tests only
cargo test -p edgefirst-tensor --doc -- --test-threads=1

# With ndarray feature exercised explicitly
cargo test -p edgefirst-tensor --features ndarray -- --test-threads=1
```

## Special Requirements

- **DMA tests** require Linux **and** read+write access to a DMA-heap device
  (typically `/dev/dma_heap/linux,cma` or `/dev/dma_heap/system`). On a workstation
  this usually means being in the `video` group. If permissions are missing,
  DMA tests are skipped at runtime and the suite falls back to heap-only
  coverage; nothing fails outright. Set `EDGEFIRST_TENSOR_FORCE_MEM=1` to
  skip even the probe.
- **PBO tests** live in
  [`crates/tensor/src/pbo.rs`](https://github.com/EdgeFirstAI/hal/blob/main/crates/tensor/src/pbo.rs)
  and exercise `PboTensor` against a mock `PboOps` implementation. They
  are not gated on any feature — `cargo test -p edgefirst-tensor` runs
  them on every host. End-to-end PBO behavior (real GL thread, EGL
  context) is additionally exercised by the image crate's tests.
- **No LFS testdata.** All shapes and inputs are synthesized in-test.
  `tensor_benchmark` does not use `edgefirst_bench::testdata`; it
  generates its inputs in memory.
- **No feature flags required by default**; `ndarray` is on by default
  and is required for `view()` / `view_mut()` doc-tests.

## Benchmarks

```bash
# Native-host benchmark
cargo bench -p edgefirst-tensor

# Cross-compile for a target (see the project Makefile / BENCHMARKS.md
# for the full deploy workflow)
cargo-zigbuild zigbuild --target aarch64-unknown-linux-gnu --release \
  -p edgefirst-tensor --bench tensor_benchmark
```

| Benchmark | Source | What it measures |
|-----------|--------|------------------|
| `tensor_benchmark` | [`benches/tensor_benchmark.rs`](https://github.com/EdgeFirstAI/hal/blob/main/crates/tensor/benches/tensor_benchmark.rs) | Allocation cost across DMA/SHM/Mem backends; map/unmap throughput; clone_fd cost |

## Coverage Notes

- The crate participates in workspace `cargo llvm-cov`; lcov output
  appears under `crates/tensor/`.
- `cfg(target_os = "linux")`-gated code (`dma.rs`, `dmabuf.rs`) is only
  exercised on the Linux host runners and on the i.MX 8M Plus hardware
  runner. The macOS CI leg covers the heap path. There is no Windows
  test job today; SHM coverage comes from the Linux runners (where
  `shm.rs` is `#[cfg(unix)]`-gated and active).
- The `procfs` dev-dependency on Linux is used to read open-fd counts
  for the current process via `procfs::process::Process::myself()` —
  the leak-regression tests assert that fd count returns to its
  baseline after DMA / SHM tensors are dropped. The check is fd-count
  based, not a `/proc/self/maps` parse.

## Cross-References

- Project testing patterns: [../../TESTING.md](https://github.com/EdgeFirstAI/hal/blob/main/TESTING.md)
- Validating optimizations: [TESTING.md#validating-optimizations](https://github.com/EdgeFirstAI/hal/blob/main/TESTING.md#validating-optimizations)
- Image-side PBO testing: [../image/TESTING.md](https://github.com/EdgeFirstAI/hal/blob/main/crates/image/TESTING.md)
- C API DMA tests: [../capi/TESTING.md](https://github.com/EdgeFirstAI/hal/blob/main/crates/capi/TESTING.md)