itest: New macro, support for tmt and debian autopkgtest, and more

A lot of stuff for itest, which is our Rust-based test framework
for integration testing.

Fork-exec output capture: when not running under nextest or tmt, the
harness re-executes itself per test to capture stdout/stderr, matching
cargo test default behavior.  ITEST_NOCAPTURE=1 disables for debugging.

Test metadata generation: --emit-tmt and --emit-autopkgtest flags
generate FMF and DEP-8 metadata from registered tests, enabling tmt
and autopkgtest to discover and run individual tests.  Verified
end-to-end with tmt.

TestMeta: per-test metadata struct (timeout, needs_root, isolation,
tags, summary, needs_internet, flaky) that maps to tmt and autopkgtest
fields.  Stored in distributed slices alongside test functions.

Proc macro (#[itest::test_attr]): attribute macro that replaces the
declarative macros for cleaner ergonomics.  Preserves doc comments,
handles error type conversion (anyhow/eyre/io::Error), supports async
fn via automatic tokio runtime creation, and accepts all metadata as
attribute arguments.

VM instance type: privileged_test! and booted_test! accept itype for
VM sizing, threaded through require_root() to bcvk --itype.

The Justfile now prefers nextest with cargo test fallback, and fixes a
pre-existing bug where set -e skipped cleanup on test failure.

Assisted-by: OpenCode (Claude Opus 4)
Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

Cargo.lock

@@ -24,7 +24,8 @@ unit *ARGS:
 pull-test-images:
     podman pull -q {{ALL_BASE_IMAGES}} >/dev/null
 
-# Run integration tests (auto-detects nextest, with cleanup)
+# Run integration tests (prefers cargo-nextest, falls back to cargo test with
+# built-in fork-exec output capture)
 test-integration *ARGS: build pull-test-images
     #!/usr/bin/env bash
     set -euo pipefail
@@ -36,16 +37,15 @@ test-integration *ARGS: build pull-test-images
     # Clean up any leftover containers before starting
     cargo run --release --bin test-cleanup -p integration-tests 2>/dev/null || true
 
-    # Run the tests
+    # Prefer nextest for better UX (retries, timing, etc.), but the harness
+    # captures output itself via fork-exec so cargo test works too.
     if command -v cargo-nextest &> /dev/null; then
-        cargo nextest run --release -P integration -p integration-tests {{ ARGS }}
-        TEST_EXIT_CODE=$?
+        cargo nextest run --release -P integration -p integration-tests {{ ARGS }} && TEST_EXIT_CODE=0 || TEST_EXIT_CODE=$?
     else
-        cargo test --release -p integration-tests -- {{ ARGS }}
-        TEST_EXIT_CODE=$?
+        cargo test --release -p integration-tests -- {{ ARGS }} && TEST_EXIT_CODE=0 || TEST_EXIT_CODE=$?
     fi
 
-    # Clean up containers after tests complete
+    # Clean up containers after tests complete (must run even on failure)
     cargo run --release --bin test-cleanup -p integration-tests 2>/dev/null || true
 
     exit $TEST_EXIT_CODE

Justfile

@@ -0,0 +1,17 @@
+[package]
+name = "itest-macros"
+version = "0.1.0"
+edition = "2021"
+publish = false
+description = "Proc-macro companion crate for itest"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1"
+quote = "1"
+syn = { version = "2", features = ["full", "extra-traits"] }
+
+[lints]
+workspace = true