ptest-cargo.bbclass: create class

This new class offers the possibility to build rust unit tests
(and integration tests) and find them correctly.
Due to non deterministic names of generated binaries, a custom
parsing of build result must be performed.
See rust-lang/cargo#1924

All rust projects will generate a test binary with "cargo build --tests"
command, even if there are no test defined in source code.
The binary will just output that it ran 0 tests.

Signed-off-by: Frederic Martinsons <frederic.martinsons@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

meta/classes-recipe/ptest-cargo.bbclass

@@ -0,0 +1,130 @@
+inherit cargo ptest
+
+# I didn't find a cleaner way to share data between compile and install tasks
+CARGO_TEST_BINARIES_FILES ?= "${B}/test_binaries_list"
+
+# Sadly, generated test binaries have no deterministic names (https://github.com/rust-lang/cargo/issues/1924)
+# This forces us to parse the cargo output in json format to find those test binaries.
+python do_compile_ptest_cargo() {
+    import subprocess
+    import json
+
+    cargo = bb.utils.which(d.getVar("PATH"), d.getVar("CARGO", True))
+    cargo_build_flags = d.getVar("CARGO_BUILD_FLAGS", True)
+    rust_flags = d.getVar("RUSTFLAGS", True)
+    manifest_path = d.getVar("MANIFEST_PATH", True)
+
+    env = os.environ.copy()
+    env['RUSTFLAGS'] = rust_flags
+    cmd = f"{cargo} build --tests --message-format json {cargo_build_flags}"
+    bb.note(f"Building tests with cargo ({cmd})")
+
+    try:
+        proc = subprocess.Popen(cmd, shell=True, env=env, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+    except subprocess.CalledProcessError as e:
+        bb.fatal(f"Cannot build test with cargo: {e}")
+
+    lines = []
+    for line in proc.stdout:
+        data = line.decode('utf-8').strip('\n')
+        lines.append(data)
+        bb.note(data)
+    proc.communicate()
+    if proc.returncode != 0:
+        bb.fatal(f"Unable to compile test with cargo, '{cmd}' failed")
+
+    # Definition of the format: https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages
+    test_bins = []
+    for line in lines:
+        try:
+            data = json.loads(line)
+        except json.JSONDecodeError:
+            # skip lines that are not a json
+            pass
+        else:
+            try:
+                # Filter the test packages coming from the current manifest
+                current_manifest_path = os.path.normpath(data['manifest_path'])
+                project_manifest_path = os.path.normpath(manifest_path)
+                if current_manifest_path == project_manifest_path:
+                    if data['target']['test'] or data['target']['doctest'] and data['executable']:
+                        test_bins.append(data['executable'])
+            except KeyError as e:
+                # skip lines that do not meet the requirements
+                pass
+
+    # All rust project will generate at least one unit test binary
+    # It will just run a test suite with 0 tests, if the project didn't define some
+    # So it is not expected to have an empty list here
+    if not test_bins:
+        bb.fatal("Unable to find any test binaries")
+
+    cargo_test_binaries_file = d.getVar('CARGO_TEST_BINARIES_FILES', True)
+    bb.note(f"Found {len(test_bins)} tests, write their paths into {cargo_test_binaries_file}")
+    with open(cargo_test_binaries_file, "w") as f:
+        for test_bin in test_bins:
+            f.write(f"{test_bin}\n")
+
+}
+
+python do_install_ptest_cargo() {
+    import shutil
+
+    dest_dir = d.getVar("D", True)
+    pn = d.getVar("PN", True)
+    ptest_path = d.getVar("PTEST_PATH", True)
+    cargo_test_binaries_file = d.getVar('CARGO_TEST_BINARIES_FILES', True)
+
+    ptest_dir = os.path.join(dest_dir, ptest_path.lstrip('/'))
+    os.makedirs(ptest_dir, exist_ok=True)
+
+    test_bins = []
+    with open(cargo_test_binaries_file, "r") as f:
+        for line in f.readlines():
+            test_bins.append(line.strip('\n'))
+
+    test_paths = []
+    for test_bin in test_bins:
+        shutil.copy2(test_bin, ptest_dir)
+        test_paths.append(os.path.join(ptest_path, os.path.basename(test_bin)))
+
+    ptest_script = os.path.join(ptest_dir, "run-ptest")
+    if os.path.exists(ptest_script):
+        with open(ptest_script, "a") as f:
+            f.write(f"\necho \"\"\n")
+            f.write(f"echo \"## starting to run rust tests ##\"\n")
+            for test_path in test_paths:
+                f.write(f"{test_path}\n")
+    else:
+        with open(ptest_script, "a") as f:
+            f.write("#!/bin/sh\n")
+            for test_path in test_paths:
+                f.write(f"{test_path}\n")
+        os.chmod(ptest_script, 0o755)
+
+    # this is chown -R root:root ${D}${PTEST_PATH}
+    for root, dirs, files in os.walk(ptest_dir):
+        for d in dirs:
+            shutil.chown(os.path.join(root, d), "root", "root")
+        for f in files:
+            shutil.chown(os.path.join(root, f), "root", "root")
+}
+
+do_install_ptest_cargo[dirs] = "${B}"
+do_install_ptest_cargo[doc] = "Create or update the run-ptest script with rust test binaries generated"
+do_compile_ptest_cargo[dirs] = "${B}"
+do_compile_ptest_cargo[doc] = "Generate rust test binaries through cargo"
+
+addtask compile_ptest_cargo after do_compile            before do_compile_ptest_base
+addtask install_ptest_cargo after do_install_ptest_base before do_package
+
+python () {
+    if not bb.data.inherits_class('native', d) and not bb.data.inherits_class('cross', d):
+        d.setVarFlag('do_install_ptest_cargo', 'fakeroot', '1')
+        d.setVarFlag('do_install_ptest_cargo', 'umask', '022')
+
+    # Remove all '*ptest_cargo' tasks when ptest is not enabled
+    if not(d.getVar('PTEST_ENABLED') == "1"):
+        for i in ['do_compile_ptest_cargo', 'do_install_ptest_cargo']:
+            bb.build.deltask(i, d)
+}