bin: add --list flag to list all rules (#8)

It is useful to know what rules exist. In the future, these need to be
documented.

Semver: minor

Author: evanlucas

README.md

@@ -19,6 +19,16 @@ $ core-validate-commit <sha>
 
 # validate since <sha>
 $ git rev-list <sha>..HEAD | xargs core-validate-commit
+
+# list all rules
+$ core-validate-commit --list
+    fixes-url enforce format of Fixes URLs
+  line-length enforce max length of lines in commit body
+ metadata-end enforce that metadata is at the end of commit messages
+       pr-url enforce PR-URL
+    reviewers enforce having reviewers
+    subsystem enforce subsystem validity
+ title-length enforce max length of commit title
 ```
 
 ## Test

bin/cmd.js

@@ -13,17 +13,20 @@ const pretty = require('../lib/format-pretty')
 const formatTap = require('../lib/format-tap')
 const Validator = require('../lib')
 const Tap = require('../lib/tap')
+const utils = require('../lib/utils')
 const knownOpts = { help: Boolean
                   , version: Boolean
                   , 'validate-metadata': Boolean
                   , tap: Boolean
                   , out: path
+                  , list: Boolean
                   }
 const shortHand = { h: ['--help']
                   , v: ['--version']
                   , V: ['--validate-metadata']
                   , t: ['--tap']
                   , o: ['--out']
+                  , l: ['--list']
                   }
 
 const parsed = nopt(knownOpts, shortHand)
@@ -79,6 +82,19 @@ function loadPatch(uri, cb) {
 
 const v = new Validator(parsed)
 
+if (parsed.list) {
+  const ruleNames = Array.from(v.rules.keys())
+  const max = ruleNames.reduce((m, item) => {
+    if (item.length > m) m = item.length
+    return m
+  }, 0)
+
+  for (const rule of v.rules.values()) {
+    utils.describeRule(rule, max)
+  }
+  return
+}
+
 if (parsed.tap) {
   const stream = parsed.out
     ? fs.createWriteStream(parsed.out)

bin/usage.txt

@@ -7,6 +7,7 @@ core-validate-commit - Validate the commit message for a particular commit in no
     -v, --version                 show version
     -V, --validate-metadata       validate PR-URL and revieweres (on by default)
     -t, --tap                     output in tap format
+    -l, --list                    list rules and their descriptions
 
   examples:
     Validate a single sha:

lib/utils.js

@@ -17,6 +17,14 @@ exports.rightPad = function rightPad(str, max) {
   return str
 }
 
+exports.leftPad = function leftPad(str, max) {
+  const diff = max - str.length + 1
+  if (diff > 0) {
+    return `${' '.repeat(diff)}${str}`
+  }
+  return str
+}
+
 exports.header = (sha, status) => {
   switch (status) {
     case 'skip':
@@ -29,3 +37,11 @@ exports.header = (sha, status) => {
       return `${X}  ${chalk.underline(sha)}`
   }
 }
+
+exports.describeRule = function describeRule(rule, max = 20) {
+  if (rule.meta && rule.meta.description) {
+    const desc = rule.meta.description
+    const title = exports.leftPad(rule.id, max)
+    console.log(' %s %s', chalk.red(title), chalk.dim(desc))
+  }
+}