(CommandList
  children: [
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:test_description)
          op: Equal
          rhs: {(DQ ('Test diff --no-index performance'))}
          spids: [4]
        )
      ]
      spids: [4]
    )
    (C {(.)} {(./perf-lib.sh)})
    (C {(test_perf_large_repo)})
    (C {(test_checkout_worktree)})
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:file1)
          op: Equal
          rhs: 
            {
              (CommandSubPart
                command_list: 
                  (CommandList
                    children: [
                      (Pipeline
                        children: [(C {(git)} {(ls-files)}) (C {(tail)} {(-n)} {(2)}) (C {(head)} {(-1)})]
                        negated: False
                      )
                    ]
                  )
                left_token: <Left_CommandSub '$('>
                spids: [21 39]
              )
            }
          spids: [20]
        )
      ]
      spids: [20]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:file2)
          op: Equal
          rhs: 
            {
              (CommandSubPart
                command_list: 
                  (CommandList
                    children: [
                      (Pipeline
                        children: [(C {(git)} {(ls-files)}) (C {(tail)} {(-n)} {(1)}) (C {(head)} {(-1)})]
                        negated: False
                      )
                    ]
                  )
                left_token: <Left_CommandSub '$('>
                spids: [42 60]
              )
            }
          spids: [41]
        )
      ]
      spids: [41]
    )
    (C {(test_expect_success)} {(DQ ('empty files, so they take no time to diff'))} 
      {
        (DQ ('\n') ('\techo >') ($ VSub_Name '$file1') (' &&\n') ('\techo >') ($ VSub_Name '$file2') ('\n'))
      }
    )
    (C {(test_perf)} {(DQ ('diff --no-index'))} 
      {
        (DQ ('\n') ('\tgit diff --no-index ') ($ VSub_Name '$file1') (' ') ($ VSub_Name '$file2') 
          (' >/dev/null\n')
        )
      }
    )
    (C {(test_done)})
  ]
)