zephyr: Add wrapper script for calling twister

Add a wrapper script that helps invoke twister with the correct
configuration and defaults for running EC tests. Developers can simply
run `./twister` from `src/platform/ec` to run all Twister-compatible EC
tests, or specify specific tests to run by adding `-T path/to/testroot`
arguments. Other CLI args are passed straight through to Twister.

This CL also adds a testcase.yaml file to the `math` test, allowing it
to be run through Twister:

```
cd $CROS_WORKON_SRCROOT/src/platform/ec
./twister (or)
./twister -T zephyr/test/math
```

Twister's output directories, `twister-out` and `twister-out.N` have
been added to the `.gitignore`.

The `firmware_builder.py` CQ script now also calls Twister and can merge
in coverage reports.

BRANCH=None
BUG=None
TEST=./twister

Signed-off-by: Tristan Honscheid <honscheid@google.com>
Change-Id: If6ff10ffb76655912c96a66aec28d12dcebd1764
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3773766
Reviewed-by: Yuval Peress <peress@google.com>

4 files changed, 150 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index 49c5321a0c..75a29bf672 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,3 +31,6 @@ zephyr/zmake/.coverage
 # Clangd language server
 .cache/clangd/index/*
 compile_commands.json
+
+# Twister test output directories
+twister-out*
diff --git a/twister b/twister
new file mode 120000
index 0000000000..7b6dd74c5c
--- /dev/null
+++ b/twister
@@ -0,0 +1 @@
+util/twister_launcher.py
\ No newline at end of file
diff --git a/util/twister_launcher.py b/util/twister_launcher.py
new file mode 100755
index 0000000000..783d2a7ad9
--- /dev/null
+++ b/util/twister_launcher.py
@@ -0,0 +1,132 @@
+#!/usr/bin/env python3
+
+# Copyright 2022 The ChromiumOS Authors.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+This script is a wrapper for invoking Twister, the Zephyr test runner, using
+default parameters for the ChromiumOS EC project. For an overview of CLI
+parameters that may be used, please consult the Twister documentation.
+"""
+
+import argparse
+import os
+import subprocess
+from pathlib import Path
+
+
+def find_checkout() -> Path:
+    """Find the location of the source checkout or raise an error."""
+    # cros_checkout = os.environ.get("CROS_WORKON_SRCROOT")
+    # if cros_checkout is not None:
+    #     return Path(cros_checkout)
+
+    # Attempt to locate checkout location relatively if being run outside of chroot.
+    try:
+        cros_checkout = Path(__file__).resolve().parents[4]
+        assert (cros_checkout / "src").exists()
+        return cros_checkout
+    except (IndexError, AssertionError) as err:
+        raise RuntimeError(
+            "Cannot locate the checkout source root. Try entering the chroot or "
+            "making sure your directory structure matches it."
+        ) from err
+
+
+def find_modules(mod_dir: Path) -> list:
+    """Find Zephyr modules in the given directory `dir`."""
+
+    modules = []
+    for child in mod_dir.iterdir():
+        if child.is_dir() and (child / "zephyr" / "module.yml").exists():
+            modules.append(child)
+    return modules
+
+
+def main():
+    """Run Twister using defaults for the EC project."""
+
+    # Determine where the source tree is checked out.
+    cros_checkout = find_checkout()
+
+    # Use ZEPHYR_BASE environment var, or compute from checkout path if not
+    # specified.
+    zephyr_base = Path(
+        os.environ.get(
+            "ZEPHYR_BASE",
+            cros_checkout / "src" / "third_party" / "zephyr" / "main",
+        )
+    )
+
+    ec_base = cros_checkout / "src" / "platform" / "ec"
+
+    # Module paths, including third party modules and the EC application.
+    zephyr_modules = find_modules(cros_checkout / "src" / "third_party" / "zephyr")
+    zephyr_modules.append(ec_base)
+
+    # Prepare environment variables for export to Twister and inherit the
+    # parent environment.
+    twister_env = dict(os.environ)
+    twister_env.update(
+        {
+            "ZEPHYR_BASE": str(zephyr_base),
+            "TOOLCHAIN_ROOT": str(zephyr_base),
+            "ZEPHYR_TOOLCHAIN_VARIANT": "host",
+        }
+    )
+
+    # Twister CLI args
+    twister_cli = [
+        str(zephyr_base / "scripts" / "twister"),  # Executable path
+        "--ninja",
+        f"-x=DTS_ROOT={str( ec_base / 'zephyr')}",
+        f"-x=SYSCALL_INCLUDE_DIRS={str(ec_base / 'zephyr' / 'include' / 'drivers')}",
+        f"-x=ZEPHYR_MODULES={';'.join([str(p) for p in zephyr_modules])}",
+    ]
+
+    # `-T` flags (used for specifying test directories to build and run)
+    # require special handling. When run without `-T` flags, Twister will
+    # search for tests in `zephyr_base`. This is undesirable and we want
+    # Twister to look in the EC tree by default, instead. Use argparse to
+    # intercept `-T` flags and pass in a new default if none are found. If
+    # user does pass their own `-T` flags, pass them through instead. Do the
+    # same with verbosity. Other arguments get passed straight through,
+    # including -h/--help so that Twister's own help text gets displayed.
+    parser = argparse.ArgumentParser(add_help=False)
+    parser.add_argument("-T", "--testsuite-root", action="append")
+    parser.add_argument("-v", "--verbose", action="count", default=0)
+    intercepted_args, other_args = parser.parse_known_args()
+
+    for _ in range(intercepted_args.verbose):
+        # Pass verbosity setting through to twister
+        twister_cli.append("-v")
+
+    if intercepted_args.testsuite_root:
+        # Pass user-provided -T args when present.
+        for arg in intercepted_args.testsuite_root:
+            twister_cli.extend(["-T", arg])
+    else:
+        # Use EC base dir when no -T args specified. This will cause all
+        # Twister-compatible EC tests to run.
+        twister_cli.extend(["-T", str(ec_base)])
+
+    # Append additional user-supplied args
+    twister_cli.extend(other_args)
+
+    # Print exact CLI args and environment variables depending on verbosity.
+    if intercepted_args.verbose > 0:
+        print("Calling:", twister_cli)
+    if intercepted_args.verbose > 1:
+        print("With environment:", twister_env)
+
+    # Invoke Twister and wait for it to exit.
+    with subprocess.Popen(
+        twister_cli,
+        env=twister_env,
+    ) as proc:
+        proc.wait()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/zephyr/firmware_builder.py b/zephyr/firmware_builder.py
index fb1bbac6c0..c6cf0b0afc 100755
--- a/zephyr/firmware_builder.py
+++ b/zephyr/firmware_builder.py
@@ -185,8 +185,19 @@ def test(opts):
     ret = subprocess.run(cmd, check=True).returncode
     if ret:
         return ret
+
+    # Twister-based tests
+    platform_ec = zephyr_dir.parent
+    cmd = [platform_ec / "twister", "--outdir", platform_ec / "twister-out"]
+    if opts.code_coverage:
+        # Tell Twister to collect coverage data. We must specify an explicit platform
+        # type in this case, as well.
+        cmd.extend(["--coverage", "-p", "native_posix"])
+    ret = subprocess.run(cmd, check=True).returncode
+    if ret:
+        return ret
+
     if opts.code_coverage:
-        platform_ec = zephyr_dir.parent
         build_dir = platform_ec / "build" / "zephyr"
         # Merge lcov files here because bundle failures are "infra" failures.
         cmd = [
@@ -199,6 +210,8 @@ def test(opts):
             build_dir / "all_tests.info",
             "-a",
             build_dir / "all_builds.info",
+            "-a",
+            platform_ec / "twister-out" / "coverage.info",
         ]
         output = subprocess.run(
             cmd,