Refactor code structure for improved readability and maintainability; removed redundant code blocks and optimized function calls.

scripts/api-compat-changelog.test.mjs

@@ -0,0 +1,26 @@
+import assert from 'assert';
+import { fileURLToPath } from 'url';
+import path from 'path';
+import { execFileSync } from 'child_process';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const root = path.join(__dirname, '..');
+
+const fixturesDir = path.join(root, 'scripts', '__fixtures__', 'api-compat');
+const oldSpec = path.join(fixturesDir, 'old.yaml');
+const newSpec = path.join(fixturesDir, 'new.yaml');
+
+const output = execFileSync('node', ['scripts/api-compat-changelog.mjs', oldSpec, newSpec, '--title', 'Test Report'], {
+  cwd: root,
+  encoding: 'utf8',
+});
+
+assert(output.includes('# Test Report'));
+assert(output.includes('Additive operations: 1'));
+assert(output.includes('Breaking operations: 0'));
+assert(output.includes('- get /bar'));
+assert(output.includes('- get /foo -> 201'));
+assert(output.includes('- get /foo -> 200'));
+
+console.log('api-compat-changelog test passed');