Input validation for Units

Maintainer:Masatake YAMATO <>

We have to maintain parsers for languages that we don’t know well. We don’t have enough time to learn the languages.

Units test cases help us not introduce wrong changes to a parser.

However, there is still an issue; a developer who doesn’t know a target language well may write a broken test input file for the language. Here comes “Input validation.”

You can validate the test input files of Units with validate-input make target if a validator for a language is defined.

How to run and an example session

Here is an example validating an input file for JSON.

$ make validate-input VALIDATORS=jq
Category: ROOT
simple-json.d/input.json with jq                                 valid

  #valid:                                 1
  #invalid:                               0
  #skipped (known invalidation)           0
  #skipped (validator unavailable)        0

This example shows validating simple-json.d/input.json as an input file with jq validator. With VALIDATORS variable passed via command-line, you can specify validators to run. Multiple validators can be specified using a comma-separated list. If you don’t give VALIDATORS, the make target tries to use all available validators.

The meanings of “valid” and “invalid” in “Summary” are apparent. In two cases, the target skips validating input files:

#skipped (known invalidation)

A test case specifies KNOWN-INVALIDATION in its validator file.

#skipped (validator unavailable)

A command for a validator is not available.

validator file

validator file in a Units test directory specifies which validator the make target should use.

$ cat Units/simple-json.d/validator

If you put validator file to a category directory (a directory having .r suffix), the make target uses the validator specified in the file as default. The default validator can be overridden with a validator file in a subdirectory.

$ cat Units/parser-puppetManifest.r/validator
# cat Units/parser-puppetManifest.r/puppet-append.d/validator

In the example, the make target uses puppet validator for validating the most of all input files under Units/parser-puppetManifest.r directory. An exception is an input file under Units/parser-puppetManifest.r/puppet-append.d directory. The directory has its specific validator file.

If a Unit test case doesn’t have expected.tags file, the make target doesn’t run the validator on the file even if a default validator is given in its category directory.

If a Unit test case specifies KNOWN-INVALIDATION in its validator file, the make target just increments “#skipped (known invalidation)” counter. The target reports the counter at the end of execution.

validator command

A validator specified in a validator file is a command file put under misc/validators directory. The command must have “validator-” as prefix in its file name. For an example, misc/validators/validator-jq is the command for “jq”.

The command file must be an executable. validate-input make target runs the command in two ways.

is_runnable method

Before running the command as a validator, the target runs the command with “is_runnable” as the first argument. A validator command can let the target know whether the validator command is runnable or not with exit status. 0 means ready to run. Non-zero means not ready to run.

The make target never runs the validator command for validation purpose if the exit status is non-zero.

For an example, misc/validators/validator-jq command uses jq command as its backend. If jq command is not available on a system, validator-jq can do nothing. If such case, is_runnable method of validator-jq command should exit with non-zero value.

validate method

The make target runs the command with “validate* and an input file name for validating the input file. The command exits non-zero if the input file contains invalid syntax. This method will never run if is_runnable method of the command exits with non-zero.