Merge pull request #6 from uber/defaults

Add defaults

Author: lxe

.travis.yml

@@ -3,5 +3,5 @@ node_js:
   - "0.8"
   - "0.10"
   - "0.11"
-before_install: npm i npm@latest -g
+before_install: npm i npm@~1.4.6 -g
 script: npm run travis

README.md

@@ -60,7 +60,8 @@ zero-config := (dirname: String, opts?: {
     dc?: String,
     blackList?: Array<String>,
     env?: Object<String, String>,
-    seed?: Object<String, Any>
+    seed?: Object<String, Any>,
+    defaults?: Object<String, Any>
 }) => {
     get: (keypath?: Keypath) => Any,
     set: ((keypath: Keypath, value: Any) => void) &
@@ -107,6 +108,8 @@ Below are the sources it reads in order of least precendence.
     you pass `--foo='bar' --bar.baz='bob'` you will get
     `{ "foo": "bar", "bar": { "baz": "bob" } }`
  - a seed object of manual overwrites for testing purposes.
+ - a defaults object that populates values that have 
+    not been set by any other means.
 
 The config loader also uses `config-chain` for the actual
   loading logic so you can read [their docs][config-chain]
@@ -203,6 +206,17 @@ The `seed` option is very useful for testing purposes, it allows
 This is an alternative to the `NODE_ENV=test `pattern, we highly
   recommend that you do not have a `test.json` file at all.
 
+#### `opts.defaults`
+
+`opts.defaults` is optional, it can be set to an object.
+
+If it exists, it will populate all the values that are unset 
+  (but not undefined) in the loaded config with those in 
+  `opts.defaults`.
+
+The difference between `defaults` and `seed` is that `seed` over-
+  writes set values, while `defaults` does not.
+
 #### `var value = config.get(keypath)`
 
 `config.get(keypath)` will return the value at a keypath. The 

get-config-state.js

@@ -43,7 +43,9 @@ function getConfigState(dirname, opts) {
         // load ./config/NODE_ENV.json
         NODE_ENV ? join(configFolder, NODE_ENV + '.json') : null,
         // load ./config/common.json
-        join(configFolder, 'common.json')
+        join(configFolder, 'common.json'),
+        // load defaults
+        opts.defaults || null
     );
 
     // there is a "bug" in config-chain where it doesn't 

test/index.js

@@ -327,6 +327,58 @@ test('config({ seed: seed })', function (assert) {
     assert.end();
 });
 
+test('config({ defaults: defaults })', function (assert) {
+    var argv = [
+        '--foo', 'bar',
+        '--baz.lulz', 'some value',
+        '--baz.foob', 'thingy'
+    ];
+
+    var config = fetchConfig(__dirname, {
+        argv: argv,
+        seed: {
+            baz: {
+                lulz: 42
+            },
+            bar: 'foo',
+            shouldBeUndefined: undefined,
+            shouldBeOverwritten: 'overwrittenValue',
+            shouldBeMerged: {
+                deep: {
+                    foo: 'bar'
+                }
+            }
+        },
+        defaults: {
+            shouldBeUndefined: 'defined',
+            shouldBeFalse: false,
+            shouldBeTrue: true,
+            shouldBeNested: {
+                key: 'value'
+            },
+            shouldBeOverwritten: 'value',
+            shouldBeMerged: {
+                deep: {
+                    bar: 'baz'
+                }
+            }
+        }
+    });
+
+    assert.equal(config.get('foo'), 'bar');
+    assert.equal(config.get('baz.lulz'), 42);
+    assert.equal(config.get('baz.foob'), 'thingy');
+    assert.equal(config.get('shouldBeUndefined'), undefined);
+    assert.equal(config.get('shouldBeFalse'), false);
+    assert.equal(config.get('shouldBeTrue'), true);
+    assert.equal(config.get('shouldBeNested.key'), 'value');
+    assert.equal(config.get('shouldBeOverwritten'), 'overwrittenValue');
+    assert.equal(config.get('shouldBeMerged.deep.foo'), 'bar');
+    assert.equal(config.get('shouldBeMerged.deep.bar'), 'baz');
+
+    assert.end();
+});
+
 test('config.set(entireObj)', function t(assert) {
     var config = fetchConfig(__dirname);