[fuad-daoud]

Summary

In short: The CLI refuses a one-dash long flag such as -output, but no test put one after a flag with a separate value, where a regression would let it through and write a file named utput=ir.json. This adds fourteen rows, one after each spelling a flag ahead of it can take.

The one-dash flag check skips the value of a flag that takes one and carries on. If readAlone reported that case as refused, the scan would stop at the first such flag, and every one-dash flag after it would pass unchecked: --fail-on error -output=ir.json exited 0 and wrote a file named utput=ir.json. No row put a one-dash flag after a flag and its separate value.

This adds fourteen rows to TestRun_SingleDashLongFlagsAreRefused, one after each of these spellings of a flag ahead of the one-dash flag. A long flag has three forms: no value, a separate value and a joined value. A short flag has four: no value, a separate value, an attached value and a joined value. The last flag of a cluster of short flags takes the same four. After a separate value, a -- that the flag takes as its value is a row for a long flag, a short flag and a cluster. pflag reports a missing value from separate sites for a long flag and a short one, and reads the other spellings on their own paths. Taking a -- as a value is on the same branch as any other separate value, so its rows are there because a scan might look for -- itself, and not because of any pflag path.

Closes #829

Before and after

flowchart TB
  subgraph before ["Before"]
    b0["A later change makes the scan stop at a flag's separate value"]
    b1["--fail-on error -output=ir.json exits 0"]
    b2["A file named utput=ir.json is written, and the suite stays green"]
    b0 --> b1
    b1 --> b2
  end
  subgraph after ["After"]
    a0["A later change makes the scan stop at a flag's separate value"]
    a1["--fail-on error -output=ir.json exits 0"]
    a2["The new rows go red: they want the refusal and no file written"]
    a0 --> a1
    a1 --> a2
  end
  before ~~~ after

Loading

What it brings: A one-dash -output typed after another flag stays refused with its hint, rather than a later change turning it into a stray file.

Test plan

• CI on this head, main at 2123d296 merged in, runs make gate.
• Replacing return wantsValue with return refused in readAlone reddens the six rows whose value is separate (a long flag's, a short flag's, a cluster's, and the three -- values), each run alone; in a full run the file the first failing row leaves also reddens the rows after it, as they share a directory. The same plant under main's test file stays green, so the rows are what catch it.
• Returning nil at case wantsValue also reddens those six rows, each run alone. i += 2 in place of i++ reddens them too, and TestRun_SingleDashArgumentsThatAreNotFlags reddens under it as well, also under main's test file.
• Returning refused from that branch when !strings.HasPrefix(tok, "--") && len(tok) == 2, a shorthand on its own, reddens the two rows whose value follows a lone short flag (-o out.json and -o --), each run alone, and leaves the cluster's and the long flag's green.
• Returning refused from that branch when !strings.HasPrefix(tok, "--") && len(tok) > 2 reddens the two cluster rows with a separate value (-ho out.json and -ho --), each run alone; the binary then exits 0 on -ho out.json -output=ir.json and prints help, where this tree exits 2.
• Returning standsAlone from that branch for the same cluster condition reddens the cluster -- row alone, run alone; the binary then exits 0 on -ho -- -output=ir.json and prints help, and exits 2 on -ho -output=ir.json, where this tree exits 2 and 0 and prints help, respectively.
• Cutting rest at its first -- before the scan reddens the three -- value rows, run alone; the binary then exits 0 on -o -- -output=ir.json and writes utput=ir.json, where this tree exits 2. Cutting rest at a -- only when the token before it is a long flag reddens the long flag's -- row alone, run alone, and --output -- -output=ir.json then writes utput=ir.json.
• Stopping the scan at exactly --pretty, --fail-on=error, -oout.json or -o=out.json reddens that spelling's row, run alone, and leaves the other three green; under each such plant the row file before this change stays green and the binary writes utput=ir.json.
• Stopping the scan at exactly -h reddens its row, run alone; the binary then exits 0, prints help and writes nothing, where this tree exits 2.
• Stopping the scan at exactly -hoout.json, -ho=out.json or -hh reddens that cluster's row, run alone, and leaves the others green; stopping at any token that sets more than one flag reddens those three rows together. The binary then exits 0, prints help and writes nothing on each, where this tree exits 2.
• Against the plant's binary, --fail-on error -output=ir.json exits 0 and writes utput=ir.json; on this tree it exits 2 and writes nothing.