add debug mode (#216)

* add debug mode

* add restore utils

* add docs restore

Author: Eomm

README.md

@@ -578,6 +578,31 @@ allowing user input to directly supply a schema.
 It can't be guaranteed that allowing user input for the schema couldn't feasibly expose an attack
 vector.
 
+<a name="debug"></a>
+### Debug Mode
+
+The debug mode can be activated during your development to understand what is going on when things do not
+work as you expect.
+
+```js
+const debugCompiled = fastJson({
+  title: 'default string',
+  type: 'object',
+  properties: {
+    firstName: {
+      type: 'string'
+    }
+  }
+}, { debugMode: true })
+
+console.log(debugCompiled) // it is an array of functions that can create your `stringify` function
+console.log(debugCompiled.toString()) // print a "ready to read" string function, you can save it to a file
+
+const rawString = debugCompiled.toString()
+const stringify = fastJson.restore(rawString) // use the generated string to get back the `stringify` function
+console.log(stringify({ firstName: 'Foo', surname: 'bar' })) // '{"firstName":"Foo"}'
+```
+
 <a name="acknowledgements"></a>
 ## Acknowledgements
 

index.js

@@ -138,6 +138,14 @@ function build (schema, options) {
   }
 
   dependenciesName.push(code)
+
+  if (options.debugMode) {
+    dependenciesName.toString = function () {
+      return dependenciesName.join('\n')
+    }
+    return dependenciesName
+  }
+
   return (Function.apply(null, dependenciesName).apply(null, dependencies))
 }
 
@@ -1156,3 +1164,16 @@ function isEmpty (schema) {
 }
 
 module.exports = build
+
+module.exports.restore = function (debugModeStr, options = {}) {
+  const dependencies = [debugModeStr]
+  const args = []
+  if (debugModeStr.startsWith('ajv')) {
+    dependencies.unshift('ajv')
+    args.push(new Ajv(options.ajv))
+  }
+
+  // eslint-disable-next-line
+  return (Function.apply(null, ['ajv', debugModeStr])
+    .apply(null, args))
+}

test/debug-mode.test.js

@@ -0,0 +1,65 @@
+'use strict'
+
+const test = require('tap').test
+const fjs = require('..')
+
+function build (opts) {
+  return fjs({
+    title: 'default string',
+    type: 'object',
+    properties: {
+      firstName: {
+        type: 'string'
+      }
+    },
+    required: ['firstName']
+  }, opts)
+}
+
+test('activate debug mode', t => {
+  t.plan(2)
+  const debugMode = build({ debugMode: true })
+  t.type(debugMode, Array)
+  t.like(debugMode.toString.toString(), 'join', 'to string override')
+})
+
+test('activate debug mode truthy', t => {
+  t.plan(2)
+  const debugMode = build({ debugMode: 'yes' })
+  t.type(debugMode, Array)
+  t.like(debugMode.toString.toString(), 'join', 'to string override')
+})
+
+test('to string auto-consistent', t => {
+  t.plan(2)
+  const debugMode = build({ debugMode: 1 })
+  t.type(debugMode, Array)
+
+  const str = debugMode.toString()
+  const compiled = fjs.restore(str)
+  const tobe = JSON.stringify({ firstName: 'Foo' })
+  t.deepEquals(compiled({ firstName: 'Foo', surname: 'bar' }), tobe, 'surname evicted')
+})
+
+test('to string auto-consistent with ajv', t => {
+  t.plan(2)
+  const debugMode = fjs({
+    title: 'object with multiple types field',
+    type: 'object',
+    properties: {
+      str: {
+        anyOf: [{
+          type: 'string'
+        }, {
+          type: 'boolean'
+        }]
+      }
+    }
+  }, { debugMode: 1 })
+  t.type(debugMode, Array)
+
+  const str = debugMode.toString()
+  const compiled = fjs.restore(str)
+  const tobe = JSON.stringify({ str: 'Foo' })
+  t.deepEquals(compiled({ str: 'Foo', void: 'me' }), tobe)
+})