test: add cross-platform test run module (#335)

tests/run-cross-platform-tests.test.cjs

@@ -0,0 +1,46 @@
+const { test, describe } = require('node:test');
+const assert = require('node:assert/strict');
+
+const { CROSS_PLATFORM_TEST_REASON, runCrossPlatformTests } = require('../scripts/run-cross-platform-tests.cjs');
+
+describe('run cross-platform tests module', () => {
+  test('returns pass reason on zero exit', () => {
+    const out = runCrossPlatformTests({}, {
+      spawnSync: () => ({ status: 0, stdout: 'ok', stderr: '' }),
+    });
+    assert.strictEqual(out.ok, true);
+    assert.strictEqual(out.reason, CROSS_PLATFORM_TEST_REASON.PASS);
+    assert.ok(out.command.includes('--base next'));
+  });
+
+  test('classifies infrastructure failure', () => {
+    const out = runCrossPlatformTests({}, {
+      spawnSync: () => ({ status: 2, stdout: '', stderr: 'infrastructure failure' }),
+    });
+    assert.strictEqual(out.ok, false);
+    assert.strictEqual(out.reason, CROSS_PLATFORM_TEST_REASON.INFRA_FAILURE);
+  });
+
+  test('classifies test failure from FAIL marker', () => {
+    const out = runCrossPlatformTests({}, {
+      spawnSync: () => ({ status: 1, stdout: 'linux FAIL 1/2 tests (1 failures)', stderr: '' }),
+    });
+    assert.strictEqual(out.ok, false);
+    assert.strictEqual(out.reason, CROSS_PLATFORM_TEST_REASON.TEST_FAILURE);
+  });
+
+  test('passes options through to command args', () => {
+    let cmd = null;
+    let args = null;
+    runCrossPlatformTests({ base: 'main', head: 'abc123', source: '/tmp/x', targets: 'linux' }, {
+      spawnSync: (c, a) => {
+        cmd = c;
+        args = a;
+        return { status: 0, stdout: '', stderr: '' };
+      },
+    });
+
+    assert.strictEqual(cmd, 'gsd-test');
+    assert.deepStrictEqual(args, ['--targets', 'linux', '--base', 'main', '--head', 'abc123', '--source', '/tmp/x']);
+  });
+});