feat: avoid deps vm2

move proxy-agent to peerDependencies and make it optional

closes eggjs/egg#5239

package.json

@@ -27,12 +27,11 @@
   },
   "scripts": {
     "tsd": "node test/tsd.js",
-    "test-local": "mocha -t 30000 -r intelli-espower-loader test/*.test.js",
+    "test-local": "mocha -t 30000 test/*.test.js",
     "test": "npm run lint && npm run test-local",
-    "test-cov": "istanbul cover node_modules/mocha/bin/_mocha -- -t 30000 -r intelli-espower-loader test/*.test.js",
+    "test-cov": "istanbul cover node_modules/mocha/bin/_mocha -- -t 30000 test/*.test.js",
     "ci": "npm run lint && npm run tsd && npm run test-cov",
     "lint": "jshint .",
-    "autod": "autod -w --prefix '^' -t test -e examples",
     "contributor": "git-contributor"
   },
   "dependencies": {
@@ -46,17 +45,23 @@
     "humanize-ms": "^1.2.0",
     "iconv-lite": "^0.4.15",
     "ip": "^1.1.5",
-    "proxy-agent": "^5.0.0",
     "pump": "^3.0.0",
     "qs": "^6.4.0",
     "statuses": "^1.3.1",
     "utility": "^1.16.1"
   },
+  "peerDependencies": {
+    "proxy-agent": "^5.0.0"
+  },
+  "peerDependenciesMeta": {
+    "proxy-agent": {
+      "optional": true
+    }
+  },
   "devDependencies": {
     "@types/mocha": "^5.2.5",
     "@types/node": "^10.12.18",
     "agentkeepalive": "^4.0.0",
-    "autod": "*",
     "benchmark": "^2.1.4",
     "bluebird": "*",
     "busboy": "^0.2.14",
@@ -65,14 +70,12 @@
     "egg-ci": "^1.15.0",
     "git-contributor": "^1.0.10",
     "http-proxy": "^1.16.2",
-    "intelli-espower-loader": "^1.0.1",
     "istanbul": "*",
     "jshint": "*",
     "mkdirp": "^0.5.1",
     "mocha": "3",
     "muk": "^0.5.3",
     "pedding": "^1.1.0",
-    "power-assert": "^1.4.2",
     "semver": "5",
     "spy": "^1.0.0",
     "tar": "^4.4.8",

test/non-ascii-request-header.test.js

@@ -1,6 +1,6 @@
 'use strict';
 
-var assert = require('power-assert');
+var assert = require('assert');
 var urllib = require('..');
 
 // https://github.com/node-modules/urllib/issues/198

test/timing.test.js

@@ -1,7 +1,7 @@
 'use strict';
 
 var dns = require('dns');
-var assert = require('power-assert');
+var assert = require('assert');
 var pedding = require('pedding');
 var HttpsAgent = require('agentkeepalive').HttpsAgent;
 var httpsAgent = new HttpsAgent({ keepAlive: true });