test: improve test coverage for application and response

lib/application.js

@@ -204,6 +204,7 @@ function *respond(next) {
   if (null == body) {
     this.type = 'text';
     body = this.message || String(code);
+    /* istanbul ignore else */
     if (body) this.length = Buffer.byteLength(body);
     return res.end(body);
   }

test/application.js

@@ -48,6 +48,14 @@ describe('app', function(){
     .get('/')
     .end(function(){});
   })
+
+  it('should set development env when NODE_ENV missing', function(){
+    var NODE_ENV = process.env.NODE_ENV;
+    process.env.NODE_ENV = '';
+    var app = koa();
+    process.env.NODE_ENV = NODE_ENV;
+    assert.equal(app.env, 'development');
+  })
 })
 
 describe('app.toJSON()', function(){
@@ -180,6 +188,22 @@ describe('app.onerror(err)', function(){
 
     done();
   })
+
+  it('should use err.toString() instad of err.stack', function(done){
+    var app = koa();
+    app.env = 'dev';
+
+    var err = new Error('mock stack null');
+    err.stack = null;
+
+    var output = stderr.inspectSync(function() {
+      app.onerror(err);
+    });
+
+    output.should.eql(["\n", "  Error: mock stack null\n", "\n"]);
+
+    done();
+  })
 })
 
 describe('app.respond', function(){

test/response/append.js

@@ -13,7 +13,8 @@ describe('ctx.append(name, val)', function(){
     var ctx = context();
 
     ctx.append('Set-Cookie', ['foo=bar', 'fizz=buzz']);
-    ctx.response.header['set-cookie'].should.eql(['foo=bar', 'fizz=buzz']);
+    ctx.append('Set-Cookie', 'hi=again');
+    ctx.response.header['set-cookie'].should.eql(['foo=bar', 'fizz=buzz', 'hi=again']);
   })
 
   it('should get reset by res.set(field, val)', function (){