feat(plugins): normalize plugins and have unified function signature

test/specs/pre.js

@@ -8,11 +8,13 @@ const pre = proxyquire('../../dist/pre', {
 
 const plugins = {
   verify: (release, cb) => cb(null, release),
-  analyze: () => 'major'
+  analyze: (commits, cb) => cb(null, 'major')
 }
 
 test('full pre run', (t) => {
   t.test('increase version', (tt) => {
+    tt.plan(3)
+
     pre({
       name: 'available'
     }, {
@@ -23,12 +25,12 @@ test('full pre run', (t) => {
       tt.error(err)
       tt.is(release.type, 'major')
       tt.is(release.version, '2.0.0')
-
-      tt.end()
     })
   })
 
   t.test('increase version', (tt) => {
+    tt.plan(3)
+
     pre({
       name: 'unavailable'
     }, {
@@ -39,8 +41,6 @@ test('full pre run', (t) => {
       tt.error(err)
       tt.is(release.type, 'initial')
       tt.is(release.version, '1.0.0')
-
-      tt.end()
     })
   })