[Duplicate Code] Docker bridge gateway mock block duplicated 17 times across two iptables test files

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Duplicate Code Opportunity

Summary

• Pattern: A mockedExeca.mockImplementation(...) block that stubs Docker bridge gateway resolution to return 172.17.0.1 is copy-pasted verbatim into every test that exercises the host-access iptables path
• Locations: src/host-iptables-host-access.test.ts (12 occurrences) and src/host-iptables-setup.test.ts (5 occurrences)
• Impact: 17 copies × ~8 code lines = ~136 lines of boilerplate; any change to the mock return value or structure requires 17 edits, risking drift that could silently mask iptables security regressions

Evidence

Pattern repeated in both files (representative copy from host-iptables-host-access.test.ts:57–66):

mockedExeca.mockImplementation(((cmd: string, args: string[]) => {
  if (cmd === 'docker' && args.includes('bridge')) {
    return Promise.resolve({ stdout: '172.17.0.1', stderr: '', exitCode: 0 });
  }
  return Promise.resolve({ stdout: '', stderr: '', exitCode: 0 });
}) as any);

This block appears after setupDefaultIptablesMocks() in every test that requires the Docker bridge gateway to be resolved (used by getDockerBridgeGateway() for the host-access iptables ACCEPT rules).

All occurrences:

• src/host-iptables-host-access.test.ts lines 14, 60, 99, 127, 144, 170, 202, 230, 264, 300, 332, 373 — 12 copies
• src/host-iptables-setup.test.ts lines 328, 356, 383, 394, 501 — 5 copies

Suggested Refactoring

Either extend setupDefaultIptablesMocks() to include the bridge mock by default, or add a dedicated helper:

// In the shared test-setup utility (e.g., a new host-iptables-test-utils.ts)
export function setupDockerBridgeMock(gateway = '172.17.0.1') {
  mockedExeca.mockImplementation(((cmd: string, args: string[]) => {
    if (cmd === 'docker' && args.includes('bridge')) {
      return Promise.resolve({ stdout: gateway, stderr: '', exitCode: 0 });
    }
    return Promise.resolve({ stdout: '', stderr: '', exitCode: 0 });
  }) as any);
}

Each test then replaces the 8-line inline block with a single call:

setupDockerBridgeMock();

Note: Issue #4070 (closed/completed) addressed a different pattern — duplicated expect(...) assertion blocks checking for gateway ACCEPT rules. This finding concerns the mock setup block, not the assertions.

Affected Files

• src/host-iptables-host-access.test.ts — lines 14, 60, 99, 127, 144, 170, 202, 230, 264, 300, 332, 373
• src/host-iptables-setup.test.ts — lines 328, 356, 383, 394, 501

Effort Estimate

Low

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Detected by Duplicate Code Detector workflow. Run date: 2026-06-06

Generated by Duplicate Code Detector · sonnet46 6.2M · ◷

• expires on Jul 6, 2026, 10:08 PM UTC