Add warning for specified unavailable formatter

[azu]

Currently, textlint --format unavailable-formatter throw error.

$ textlint -f unavailable-formatter README.md
✖ Error
formatter is not a function

✖ Stack trace
TypeError: formatter is not a function

But, this error is not meaningful.
We should check the formatter is available before liting.

Motivation

From #148

textlint has two type formatter.
One is linter formater, Anther is fixer formatter

• textlint/packages/textlint-formatter at master · textlint/textlint
• textlint/packages/textlint-fixer-formatter at master · textlint/textlint

This difference cause unexepected error in following scenario.

First, You run lint a text.

texlint -f pretty-error README.md

Then, the lint result has error message.

Second, You want to fix this error, and run textlint --fix.

texlint --fix -f pretty-error README.md

texlint --fix -f pretty-error throw error!
Because, fixer formater not have pretty-error formatter.

We want to add warning for this scenario.

Tasks

• Add resolveFormatter(name: string): string | null to formatter modules
• Add check script in cli.execute

textlint/packages/textlint/src/cli.ts

Line 65 in fa68399

execute(args: string | Array<any> | object, text: string): Promise<number> {

Check logic

• Lint mode
  • If linterFormatter.resolveFormatter() return null, show warning and exit 1.
• Fix(--fix) mode
  • If fixerFormatter.resolveFormatter() return null, show warning and exit 1.

Related

• formater: Add getFormatterList function formater: Add getFormatterList function #399