# term-session-mock
Internal test tooling for the [term-wm](https://crates.io/crates/term-wm) workspace. Not intended for direct use.
## What this is
A **deterministic PTY-resident test fixture** — a small, real binary that the session daemon spawns inside a PTY so tests can drive a child process with full determinism. It replaces a real shell/command in tests, removing dependency on shell availability, shell startup timing, and platform-specific command behavior.
It runs on Linux, macOS, and Windows, and includes explicit Windows ConPTY console-mode handling (raw VT input, VT-processing toggling) so ANSI sequences pass through ConPTY intact.
Every subcommand performs **real** OS behavior — real process spawning, real exit codes, real sleeping, real PIDs, real liveness probing. Nothing is hardcoded to fabricate a passing assertion; the only fixed output is the `osc52` payload, which is the exact byte sequence the OSC 52 encoder is expected to emit.
## Subcommands
| `echo` | Unbuffered stdin→stdout passthrough (like `cat`) | PTY I/O round-trip, cross-client output broadcast |
| `osc52` | Writes a fixed OSC 52 clipboard sequence to stdout, then exits | OSC 52 interception → clipboard relay |
| `sleep <ms>` | Sleeps for `ms` (default 1000), then exits | Session persistence across clients; timed exits |
| `exit <code>` | Exits with the given status code (default 0) | Exit-code propagation, session-exit handling |
| `spawn_child <ms>` | Spawns a **real grandchild** (`sleep <ms>`), prints `GRANDCHILD_PID:<pid>`, then echoes stdin until EOF | Tree-kill containment: the whole process tree dies (process group / Job Object), nothing orphans |
| `check_pid <pid>` | Exits 0 if the process is alive, non-zero otherwise | Post-kill liveness assertions (tree teardown proof) |
| `capture` | Echoes stdin back prefixed with `MOUSE_OK:` until it sees `ping` | Mouse/input event forwarding through the session |
## Why a dedicated mock
- **Determinism:** a real shell's startup, prompts, and timing vary; the mock's behavior is fixed and simple.
- **Cross-platform:** one binary behaves identically (modulo ConPTY console-mode setup) on Unix and Windows.
- **Tree-kill verification:** `spawn_child` creates an actual second process so tests can assert that killing a session terminates the grandchild — impossible to fake, and the crux of the Unix process-group / Windows Job Object containment guarantees.
- **No production footprint:** this crate is test-only; nothing in the shipped binaries depends on it.
## Finding the binary
Test suites locate the compiled binary through [`get_mock_bin`](src/lib.rs), which:
1. honors `CARGO_BIN_EXE_term-session-mock` when Cargo provides it (this crate's own integration tests);
2. otherwise finds the workspace build in `target/debug` or the hashed `target/debug/deps` location;
3. if neither exists, **runs `cargo build` for this crate on demand** and re-resolves.
The helper never returns a missing path, so tests can never silently skip. If the binary still cannot be located after an on-demand build, it panics — a broken build fails loudly instead of quietly dropping coverage.