fix koa integration returning 404 with legacy middleware

package.json

@@ -9,10 +9,10 @@
     "jsdoc:watch": "cd docs && yarn && ./node_modules/.bin/gulp jsdoc:watch",
     "lint": "eslint . && node scripts/check_licenses.js",
     "services": "node ./scripts/install_plugin_modules && node test/setup/services",
-    "tdd": "yarn services && mocha --watch 'test/setup/**/*.js'",
-    "test": "yarn services && cov8 --include \"src/**/*.js\" -- mocha --exit 'test/setup/all.js' 'test/**/*.spec.js'",
+    "tdd": "yarn services && NO_DEPRECATION=* mocha --watch 'test/setup/**/*.js'",
+    "test": "yarn services && NO_DEPRECATION=* cov8 --include \"src/**/*.js\" -- mocha --exit 'test/setup/all.js' 'test/**/*.spec.js'",
     "test:core": "mocha --exit --exclude \"test/plugins/**/*.spec.js\" --file test/setup/core.js \"test/**/*.spec.js\"",
-    "test:plugins": "yarn services && cov8 --include \"src/**/*.js\" -- mocha --exit --file \"test/setup/all.js\" \"test/plugins/@($(echo $PLUGINS)).spec.js\" \"test/plugins/@($(echo $PLUGINS))/**/*.spec.js\"",
+    "test:plugins": "yarn services && NO_DEPRECATION=* cov8 --include \"src/**/*.js\" -- mocha --exit --file \"test/setup/all.js\" \"test/plugins/@($(echo $PLUGINS)).spec.js\" \"test/plugins/@($(echo $PLUGINS))/**/*.spec.js\"",
     "leak:core": "node ./scripts/install_plugin_modules && (cd test/leak && yarn) && NODE_PATH=./test/leak/node_modules node --no-warnings ./node_modules/.bin/tape 'test/leak/{,!(node_modules|plugins)/**/}/*.js'",
     "leak:plugins": "yarn services && (cd test/leak && yarn) && NODE_PATH=./test/leak/node_modules node --no-warnings ./node_modules/.bin/tape \"test/leak/plugins/@($(echo $PLUGINS)).js\""
   },

src/plugins/koa.js

@@ -12,16 +12,21 @@ function createWrapUse (tracer, config) {
   }
 
   return function wrapUse (use) {
-    return function useWithTrace (fn) {
+    return function useWithTrace () {
       if (!this._datadog_trace_patched) {
         this._datadog_trace_patched = true
         use.call(this, ddTrace)
       }
 
-      return use.call(this, function (ctx, next) {
+      const result = use.apply(this, arguments)
+      const fn = this.middleware.pop()
+
+      this.middleware.push(function (ctx, next) {
         web.reactivate(ctx.req)
         return fn.apply(this, arguments)
       })
+
+      return result
     }
   }
 }

test/plugins/koa.spec.js

@@ -32,7 +32,7 @@ describe('Plugin', () => {
         before(() => agent.load(plugin, 'koa'))
         after(() => agent.close())
 
-        it('should do automatic instrumentation on middleware', done => {
+        it('should do automatic instrumentation on 2.x middleware', done => {
           const app = new Koa()
 
           app.use((ctx) => {
@@ -60,6 +60,35 @@ describe('Plugin', () => {
           })
         })
 
+        it('should do automatic instrumentation on 1.x middleware', done => {
+          const app = new Koa()
+
+          app.use(function * (next) {
+            this.body = ''
+            yield next
+          })
+
+          agent
+            .use(traces => {
+              expect(traces[0][0]).to.have.property('name', 'koa.request')
+              expect(traces[0][0]).to.have.property('service', 'test')
+              expect(traces[0][0]).to.have.property('type', 'http')
+              expect(traces[0][0]).to.have.property('resource', 'GET')
+              expect(traces[0][0].meta).to.have.property('span.kind', 'server')
+              expect(traces[0][0].meta).to.have.property('http.url', `http://localhost:${port}/user`)
+              expect(traces[0][0].meta).to.have.property('http.method', 'GET')
+              expect(traces[0][0].meta).to.have.property('http.status_code', '200')
+            })
+            .then(done)
+            .catch(done)
+
+          appListener = app.listen(port, 'localhost', () => {
+            axios
+              .get(`http://localhost:${port}/user`)
+              .catch(done)
+          })
+        })
+
         it('should run middleware in the request scope', done => {
           if (process.env.DD_CONTEXT_PROPAGATION === 'false') return done()