Merge pull request #13 from moqmar/patch-1

Fix #12 by adding a _.mergeWith customizer function

index.js

@@ -20,7 +20,10 @@ function readAsJSON(fileName) {
 function yamlMerge(...from) {
   const files = from.map((path) => readAsJSON(path));
 
-  const outputJSON = _.merge({}, ...files);
+  const outputJSON = _.mergeWith({}, ...files, (objValue, srcValue, key, object, source, stack) => {
+    if (Array.isArray(objValue) && Array.isArray(srcValue)) return [...objValue, ...srcValue];
+    return undefined; // handle it just like with _.merge
+  })
   return jsYaml.dump(outputJSON);
 }
 

test/fixtures/arrays/a.yml

@@ -0,0 +1,2 @@
+key:
+- a

test/fixtures/arrays/b.yml

@@ -0,0 +1,2 @@
+key:
+- b

test/lib-test.js

@@ -47,4 +47,16 @@ describe('merge logic', function () {
     ` + '\n'
     );
   });
+
+  it('concatenates arrays instead of overwriting them', function () {
+    const output = merge(...fixtureFiles('arrays/a.yml', 'arrays/b.yml'));
+
+    expect(output).to.equal(
+      stripIndent`
+      key:
+        - a
+        - b
+    ` + '\n'
+    );
+  });
 });