fix: command completion

The fake npm object in the tests wasn't returning an async function

Fixes: https://github.com/npm/cli/issues/4020

PR-URL: https://github.com/npm/cli/pull/4032
Credit: @wraithgar
Close: #4032
Reviewed-by: @lukekarrys

1 files changed, 208 insertions, 529 deletions

diff --git a/test/lib/commands/completion.js b/test/lib/commands/completion.js
index 7a7e0a759..51212f06d 100644
--- a/test/lib/commands/completion.js
+++ b/test/lib/commands/completion.js
@@ -6,590 +6,269 @@ const completionScript = fs
   .readFileSync(path.resolve(__dirname, '../../../lib/utils/completion.sh'), { encoding: 'utf8' })
   .replace(/^#!.*?\n/, '')
 
-const output = []
-const npmConfig = {}
-let accessCompletionError = false
-
-const npm = {
-  config: {
-    set: (key, value) => {
-      npmConfig[key] = value
-    },
-    clear: () => {
-      for (const key in npmConfig) {
-        delete npmConfig[key]
-      }
-    },
-  },
-  cmd: cmd => {
-    return {
-      completion: {
-        completion: () => [['>>', '~/.bashrc']],
-      },
-      adduser: {},
-      access: {
-        completion: () => {
-          if (accessCompletionError) {
-            throw new Error('access completion failed')
-          }
-
-          return ['public', 'restricted']
-        },
-      },
-      promise: {
-        completion: () => Promise.resolve(['resolved_completion_promise']),
-      },
-      donothing: {
-        completion: () => {
-          return null
-        },
-      },
-      driveaboat: {
-        completion: () => {
-          return ' fast'
-        },
-      },
-    }[cmd]
-  },
-  output: line => {
-    output.push(line)
-  },
-}
-
-const cmdList = {
-  aliases: {
-    login: 'adduser',
-  },
-  cmdList: ['access', 'adduser', 'completion'],
-  plumbing: [],
-}
-
-// only include a subset so that the snapshots aren't huge and
-// don't change when we add/remove config definitions.
-const definitions = require('../../../lib/utils/config/definitions.js')
-const config = {
-  definitions: {
-    global: definitions.global,
-    browser: definitions.browser,
-    registry: definitions.registry,
-  },
-  shorthands: {
-    reg: ['--registry'],
-  },
-}
-
-const deref = cmd => {
-  return cmd
-}
-
-const Completion = t.mock('../../../lib/commands/completion.js', {
-  '../../../lib/utils/cmd-list.js': cmdList,
-  '../../../lib/utils/config/index.js': config,
-  '../../../lib/utils/deref-command.js': deref,
-  '../../../lib/utils/is-windows-shell.js': false,
-})
-const completion = new Completion(npm)
-
-t.test('completion completion', async t => {
-  const home = process.env.HOME
-  t.teardown(() => {
-    process.env.HOME = home
-  })
-
-  process.env.HOME = t.testdir({
-    '.bashrc': '',
-    '.zshrc': '',
-  })
+const { real: mockNpm } = require('../../fixtures/mock-npm')
 
-  const res = await completion.completion({ w: 2 })
-  t.strictSame(
-    res,
-    [
-      ['>>', '~/.zshrc'],
-      ['>>', '~/.bashrc'],
-    ],
-    'identifies both shells'
-  )
-  t.end()
+const { Npm, outputs } = mockNpm(t, {
+  '../../lib/utils/is-windows-shell.js': false,
 })
+const npm = new Npm()
+
+t.test('completion', async t => {
+  const completion = await npm.cmd('completion')
+  t.test('completion completion', async t => {
+    const home = process.env.HOME
+    t.teardown(() => {
+      process.env.HOME = home
+    })
 
-t.test('completion completion no known shells', async t => {
-  const home = process.env.HOME
-  t.teardown(() => {
-    process.env.HOME = home
-  })
+    process.env.HOME = t.testdir({
+      '.bashrc': '',
+      '.zshrc': '',
+    })
 
-  process.env.HOME = t.testdir()
+    await completion.completion({ w: 2 })
+    t.matchSnapshot(outputs, 'both shells')
+  })
 
-  const res = await completion.completion({ w: 2 })
-  t.strictSame(res, [], 'no responses')
-  t.end()
-})
+  t.test('completion completion no known shells', async t => {
+    const home = process.env.HOME
+    t.teardown(() => {
+      process.env.HOME = home
+    })
 
-t.test('completion completion wrong word count', async t => {
-  const res = await completion.completion({ w: 3 })
-  t.strictSame(res, undefined, 'no responses')
-  t.end()
-})
+    process.env.HOME = t.testdir()
 
-t.test('completion errors in windows without bash', async t => {
-  const Compl = t.mock('../../../lib/commands/completion.js', {
-    '../../../lib/utils/is-windows-shell.js': true,
+    await completion.completion({ w: 2 })
+    t.matchSnapshot(outputs, 'no responses')
   })
 
-  const compl = new Compl()
-
-  await t.rejects(
-    compl.exec({}),
-    { code: 'ENOTSUP', message: /completion supported only in MINGW/ },
-    'returns the correct error'
-  )
-})
-
-t.test('dump script when completion is not being attempted', async t => {
-  const _write = process.stdout.write
-  const _on = process.stdout.on
-  t.teardown(() => {
-    process.stdout.write = _write
-    process.stdout.on = _on
+  t.test('completion completion wrong word count', async t => {
+    await completion.completion({ w: 3 })
+    t.matchSnapshot(outputs, 'no responses')
   })
 
-  let errorHandler
-  process.stdout.on = (event, handler) => {
-    errorHandler = handler
-    process.stdout.on = _on
-  }
-
-  let data
-  process.stdout.write = (chunk, callback) => {
-    data = chunk
-    process.stdout.write = _write
-    process.nextTick(() => {
-      callback()
-      errorHandler({ errno: 'EPIPE' })
+  t.test('dump script when completion is not being attempted', async t => {
+    const _write = process.stdout.write
+    const _on = process.stdout.on
+    t.teardown(() => {
+      process.stdout.write = _write
+      process.stdout.on = _on
     })
-  }
 
-  await completion.exec({})
+    let errorHandler
+    process.stdout.on = (event, handler) => {
+      errorHandler = handler
+      process.stdout.on = _on
+    }
+
+    let data
+    process.stdout.write = (chunk, callback) => {
+      data = chunk
+      process.stdout.write = _write
+      process.nextTick(() => {
+        callback()
+        errorHandler({ errno: 'EPIPE' })
+      })
+    }
+
+    await completion.exec({})
+
+    t.equal(data, completionScript, 'wrote the completion script')
+  })
 
-  t.equal(data, completionScript, 'wrote the completion script')
-})
+  t.test('dump script exits correctly when EPIPE is emitted on stdout', async t => {
+    const _write = process.stdout.write
+    const _on = process.stdout.on
+    t.teardown(() => {
+      process.stdout.write = _write
+      process.stdout.on = _on
+    })
 
-t.test('dump script exits correctly when EPIPE is emitted on stdout', async t => {
-  const _write = process.stdout.write
-  const _on = process.stdout.on
-  t.teardown(() => {
-    process.stdout.write = _write
-    process.stdout.on = _on
+    let errorHandler
+    process.stdout.on = (event, handler) => {
+      errorHandler = handler
+      process.stdout.on = _on
+    }
+
+    let data
+    process.stdout.write = (chunk, callback) => {
+      data = chunk
+      process.stdout.write = _write
+      process.nextTick(() => {
+        errorHandler({ errno: 'EPIPE' })
+        callback()
+      })
+    }
+
+    await completion.exec({})
+    t.equal(data, completionScript, 'wrote the completion script')
   })
 
-  let errorHandler
-  process.stdout.on = (event, handler) => {
-    errorHandler = handler
-    process.stdout.on = _on
-  }
-
-  let data
-  process.stdout.write = (chunk, callback) => {
-    data = chunk
-    process.stdout.write = _write
-    process.nextTick(() => {
-      errorHandler({ errno: 'EPIPE' })
-      callback()
-    })
-  }
+  t.test('single command name', async t => {
+    process.env.COMP_CWORD = 1
+    process.env.COMP_LINE = 'npm conf'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-  await completion.exec({})
-  t.equal(data, completionScript, 'wrote the completion script')
-})
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-// This test was only working by coincidence before, when we switch to full
-// async/await the race condition now makes it impossible to test.  The root of
-// the problem is that if we override stdout.write then other things interfere
-// during testing.
-// t.test('non EPIPE errors cause failures', async t => {
-//   const _write = process.stdout.write
-//   const _on = process.stdout.on
-//   t.teardown(() => {
-//     process.stdout.write = _write
-//     process.stdout.on = _on
-//   })
-
-//   let errorHandler
-//   process.stdout.on = (event, handler) => {
-//     errorHandler = handler
-//     process.stdout.on = _on
-//   }
-
-//   let data
-//   process.stdout.write = (chunk, callback) => {
-//     data = chunk
-//     process.stdout.write = _write
-//     process.nextTick(() => {
-//       errorHandler({ errno: 'ESOMETHINGELSE' })
-//       callback()
-//     })
-//   }
-
-//   await t.rejects(
-//     completion.exec([]),
-//     { errno: 'ESOMETHINGELSE' },
-//     'propagated error'
-//   )
-//   t.equal(data, completionScript, 'wrote the completion script')
-// })
-
-t.test('completion completes single command name', async t => {
-  process.env.COMP_CWORD = 1
-  process.env.COMP_LINE = 'npm c'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    await completion.exec(['npm', 'conf'])
+    t.matchSnapshot(outputs, 'single command name')
   })
 
-  await completion.exec(['npm', 'c'])
-  t.strictSame(output, ['completion'], 'correctly completed a command name')
-})
+  t.test('multiple command names', async t => {
+    process.env.COMP_CWORD = 1
+    process.env.COMP_LINE = 'npm a'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
+
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-t.test('completion completes command names', async t => {
-  process.env.COMP_CWORD = 1
-  process.env.COMP_LINE = 'npm a'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    await completion.exec(['npm', 'a'])
+    t.matchSnapshot(outputs, 'multiple command names')
   })
 
-  await completion.exec(['npm', 'a'])
-  t.strictSame(output, [['access', 'adduser'].join('\n')], 'correctly completed a command name')
-})
+  t.test('completion of invalid command name does nothing', async t => {
+    process.env.COMP_CWORD = 1
+    process.env.COMP_LINE = 'npm compute'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
+
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-t.test('completion of invalid command name does nothing', async t => {
-  process.env.COMP_CWORD = 1
-  process.env.COMP_LINE = 'npm compute'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    await completion.exec(['npm', 'compute'])
+    t.matchSnapshot(outputs, 'no results')
   })
 
-  await completion.exec(['npm', 'compute'])
-  t.strictSame(output, [], 'returns no results')
-})
+  t.test('subcommand completion', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm access '
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-t.test('handles async completion function', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm promise'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
+
+    await completion.exec(['npm', 'access', ''])
+    t.matchSnapshot(outputs, 'subcommands')
   })
 
-  await completion.exec(['npm', 'promise', ''])
-
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'promise'],
-        cooked: ['npm', 'promise'],
-        original: ['npm', 'promise'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, ['resolved_completion_promise'], 'resolves async completion results')
-})
+  t.test('filtered subcommands', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm access p'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-t.test('completion triggers command completions', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm access '
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
+
+    await completion.exec(['npm', 'access', 'p'])
+    t.matchSnapshot(outputs, 'filtered subcommands')
   })
 
-  await completion.exec(['npm', 'access', ''])
-
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'access'],
-        cooked: ['npm', 'access'],
-        original: ['npm', 'access'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(
-    output,
-    [['public', 'restricted'].join('\n')],
-    'correctly completed a subcommand name'
-  )
-})
+  t.test('commands with no completion', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm adduser '
+    process.env.COMP_POINT = process.env.COMP_LINE.length
+
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-t.test('completion triggers filtered command completions', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm access p'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    // quotes around adduser are to ensure coverage when unescaping commands
+    await completion.exec(['npm', "'adduser'", ''])
+    t.matchSnapshot(outputs, 'no results')
   })
 
-  await completion.exec(['npm', 'access', 'p'])
-
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'access'],
-        cooked: ['npm', 'access'],
-        original: ['npm', 'access'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, ['public'], 'correctly completed a subcommand name')
-})
+  t.test('flags', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm install --v'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-t.test('completions for commands that return nested arrays are joined', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm completion '
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
-  })
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-  await completion.exec(['npm', 'completion', ''])
-
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'completion'],
-        cooked: ['npm', 'completion'],
-        original: ['npm', 'completion'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, ['>> ~/.bashrc'], 'joins nested arrays')
-})
+    await completion.exec(['npm', 'install', '--v'])
 
-t.test('completions for commands that return nothing work correctly', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm donothing '
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    t.matchSnapshot(outputs, 'flags')
   })
 
-  await completion.exec(['npm', 'donothing', ''])
-
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'donothing'],
-        cooked: ['npm', 'donothing'],
-        original: ['npm', 'donothing'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, [], 'returns nothing')
-})
+  t.test('--no- flags', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm install --no-v'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-t.test('completions for commands that return a single item work correctly', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm driveaboat '
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
-  })
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-  await completion.exec(['npm', 'driveaboat', ''])
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'driveaboat'],
-        cooked: ['npm', 'driveaboat'],
-        original: ['npm', 'driveaboat'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, ["' fast'"], 'returns the correctly escaped string')
-})
+    await completion.exec(['npm', 'install', '--no-v'])
 
-t.test('command completion for commands with no completion return no results', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm adduser '
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    t.matchSnapshot(outputs, 'flags')
   })
 
-  // quotes around adduser are to ensure coverage when unescaping commands
-  await completion.exec(['npm', "'adduser'", ''])
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'adduser'],
-        cooked: ['npm', 'adduser'],
-        original: ['npm', 'adduser'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, [], 'correctly completed a subcommand name')
-})
+  t.test('double dashes escape from flag completion', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm -- install --'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-t.test('command completion errors propagate', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm access '
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-  accessCompletionError = true
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
-    accessCompletionError = false
-  })
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-  await t.rejects(
-    completion.exec(['npm', 'access', '']),
-    /access completion failed/,
-    'catches the appropriate error'
-  )
-  t.strictSame(
-    npmConfig,
-    {
-      argv: {
-        remain: ['npm', 'access'],
-        cooked: ['npm', 'access'],
-        original: ['npm', 'access'],
-      },
-    },
-    'applies command config appropriately'
-  )
-  t.strictSame(output, [], 'returns no results')
-})
+    await completion.exec(['npm', '--', 'install', '--'])
 
-t.test('completion can complete flags', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm install --'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    t.matchSnapshot(outputs, 'full command list')
   })
 
-  await completion.exec(['npm', 'install', '--'])
+  t.test('completion cannot complete options that take a value in mid-command', async t => {
+    process.env.COMP_CWORD = 2
+    process.env.COMP_LINE = 'npm --registry install'
+    process.env.COMP_POINT = process.env.COMP_LINE.length
 
-  t.strictSame(npmConfig, {}, 'does not apply command config')
-  t.strictSame(
-    output,
-    [['--global', '--browser', '--registry', '--reg', '--no-global', '--no-browser'].join('\n')],
-    'correctly completes flag names'
-  )
-})
+    t.teardown(() => {
+      delete process.env.COMP_CWORD
+      delete process.env.COMP_LINE
+      delete process.env.COMP_POINT
+    })
 
-t.test('double dashes escape from flag completion', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm -- install --'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+    await completion.exec(['npm', '--registry', 'install'])
+    t.matchSnapshot(outputs, 'does not try to complete option arguments in the middle of a command')
   })
-
-  await completion.exec(['npm', '--', 'install', '--'])
-
-  t.strictSame(npmConfig, {}, 'does not apply command config')
-  t.strictSame(
-    output,
-    [['access', 'adduser', 'completion', 'login'].join('\n')],
-    'correctly completes flag names'
-  )
 })
 
-t.test('completion cannot complete options that take a value in mid-command', async t => {
-  process.env.COMP_CWORD = 2
-  process.env.COMP_LINE = 'npm --registry install'
-  process.env.COMP_POINT = process.env.COMP_LINE.length
-
-  t.teardown(() => {
-    delete process.env.COMP_CWORD
-    delete process.env.COMP_LINE
-    delete process.env.COMP_POINT
-    npm.config.clear()
-    output.length = 0
+t.test('windows without bash', async t => {
+  const { Npm, outputs } = mockNpm(t, {
+    '../../lib/utils/is-windows-shell.js': true,
   })
-
-  await completion.exec(['npm', '--registry', 'install'])
-  t.strictSame(npmConfig, {}, 'does not apply command config')
-  t.strictSame(output, [], 'does not try to complete option arguments in the middle of a command')
+  const npm = new Npm()
+  const completion = await npm.cmd('completion')
+  await t.rejects(
+    completion.exec({}),
+    { code: 'ENOTSUP', message: /completion supported only in MINGW/ },
+    'returns the correct error'
+  )
+  t.matchSnapshot(outputs, 'no output')
 })