diff --git a/test/ConfigTestCases.test.js b/test/ConfigTestCases.test.js
index 9ebd6f94a49..2206cef1763 100644
--- a/test/ConfigTestCases.test.js
+++ b/test/ConfigTestCases.test.js
@@ -174,7 +174,6 @@ describe("ConfigTestCases", () => {
 
 									function _require(currentDirectory, module) {
 										if (Array.isArray(module) || /^\.\.?\//.test(module)) {
-											let fn;
 											let content;
 											let p;
 											if (Array.isArray(module)) {
@@ -189,45 +188,47 @@ describe("ConfigTestCases", () => {
 												p = path.join(currentDirectory, module);
 												content = fs.readFileSync(p, "utf-8");
 											}
-											if (
-												options.target === "web" ||
-												options.target === "webworker"
-											) {
-												fn = vm.runInNewContext(
-													"(function(require, module, exports, __dirname, __filename, it, beforeEach, afterEach, expect, jest, window) {" +
-														'function nsObj(m) { Object.defineProperty(m, Symbol.toStringTag, { value: "Module" }); return m; }' +
-														content +
-														"\n})",
-													globalContext,
-													p
-												);
-											} else {
-												fn = vm.runInThisContext(
-													"(function(require, module, exports, __dirname, __filename, it, beforeEach, afterEach, expect, jest) {" +
-														"global.expect = expect; " +
-														'function nsObj(m) { Object.defineProperty(m, Symbol.toStringTag, { value: "Module" }); return m; }' +
-														content +
-														"\n})",
-													p
-												);
-											}
 											const m = {
 												exports: {}
 											};
-											fn.call(
-												m.exports,
-												_require.bind(null, path.dirname(p)),
-												m,
-												m.exports,
-												path.dirname(p),
-												p,
-												_it,
-												_beforeEach,
-												_afterEach,
+											let runInNewContext = false;
+											const moduleScope = {
+												require: _require.bind(null, path.dirname(p)),
+												module: m,
+												exports: m.exports,
+												__dirname: path.dirname(p),
+												__filename: p,
+												it: _it,
+												beforeEach: _beforeEach,
+												afterEach: _afterEach,
 												expect,
 												jest,
-												globalContext
-											);
+												_globalAssign: { expect },
+												nsObj: m => {
+													Object.defineProperty(m, Symbol.toStringTag, {
+														value: "Module"
+													});
+													return m;
+												}
+											};
+											if (
+												options.target === "web" ||
+												options.target === "webworker"
+											) {
+												moduleScope.window = globalContext;
+												runInNewContext = true;
+											}
+											if (testConfig.moduleScope) {
+												testConfig.moduleScope(moduleScope);
+											}
+											const args = Object.keys(moduleScope).join(", ");
+											if (!runInNewContext)
+												content = `Object.assign(global, _globalAssign); ${content}`;
+											const code = `(function({${args}}) {${content}\n})`;
+											const fn = runInNewContext
+												? vm.runInNewContext(code, globalContext, p)
+												: vm.runInThisContext(code, p);
+											fn.call(m.exports, moduleScope);
 											return m.exports;
 										} else if (
 											testConfig.modules &&
@@ -239,6 +240,7 @@ describe("ConfigTestCases", () => {
 									let filesCount = 0;
 
 									if (testConfig.noTests) return process.nextTick(done);
+									if (testConfig.beforeExecute) testConfig.beforeExecute();
 									for (let i = 0; i < optionsArr.length; i++) {
 										const bundlePath = testConfig.findBundle(i, optionsArr[i]);
 										if (bundlePath) {
@@ -256,9 +258,9 @@ describe("ConfigTestCases", () => {
 												"Should have found at least one bundle file per webpack config"
 											)
 										);
+									if (testConfig.afterExecute) testConfig.afterExecute();
 									if (getNumberOfTests() < filesCount)
 										return done(new Error("No tests exported by test case"));
-									if (testConfig.afterExecute) testConfig.afterExecute();
 									done();
 								});
 							})
diff --git a/test/configCases/externals/externals-system/index.js b/test/configCases/externals/externals-system/index.js
index 2e8fb5a7f1f..8f634069218 100644
--- a/test/configCases/externals/externals-system/index.js
+++ b/test/configCases/externals/externals-system/index.js
@@ -1,16 +1,11 @@
 /* This test verifies that webpack externals are properly indicated as dependencies to System.
  * Also that when System provides the external variables to webpack that the variables get plumbed
  * through correctly and are usable by the webpack bundle.
-*/
-afterEach(function(done) {
-	delete global.System;
-	done()
-})
-
+ */
 it("should get an external from System", function() {
 	const external1 = require("external1");
-	expect(external1).toBe('the external1 value');
+	expect(external1).toBe("the external1 value");
 
 	const external2 = require("external2");
-	expect(external2).toBe('the external2 value');
+	expect(external2).toBe("the external2 value");
 });
diff --git a/test/configCases/externals/externals-system/test.config.js b/test/configCases/externals/externals-system/test.config.js
new file mode 100644
index 00000000000..3f8225baf26
--- /dev/null
+++ b/test/configCases/externals/externals-system/test.config.js
@@ -0,0 +1,16 @@
+const System = require("../../../helpers/fakeSystem");
+
+module.exports = {
+	beforeExecute: () => {
+		System.init({
+			external1: "the external1 value",
+			external2: "the external2 value"
+		});
+	},
+	moduleScope(scope) {
+		scope.System = System;
+	},
+	afterExecute: () => {
+		System.execute("(anonym)");
+	}
+};
diff --git a/test/configCases/externals/externals-system/webpack.config.js b/test/configCases/externals/externals-system/webpack.config.js
index be11a7f1152..9a4ae5336e5 100644
--- a/test/configCases/externals/externals-system/webpack.config.js
+++ b/test/configCases/externals/externals-system/webpack.config.js
@@ -1,4 +1,3 @@
-const webpack = require("../../../../");
 module.exports = {
 	output: {
 		libraryTarget: "system"
@@ -6,26 +5,5 @@ module.exports = {
 	externals: {
 		external1: "external1",
 		external2: "external2"
-	},
-	plugins: [
-		new webpack.BannerPlugin({
-			raw: true,
-			banner: `
-				System = {
-					register: function(deps, fn) {
-						function dynamicExport() {}
-						var mod = fn(dynamicExport);
-						deps.forEach((dep, i) => {
-							mod.setters[i](System.registry[dep]);
-						})
-						mod.execute();
-					},
-					registry: {
-						external1: 'the external1 value',
-						external2: 'the external2 value',
-					},
-				}
-			`
-		})
-	]
+	}
 };
diff --git a/test/configCases/target/system-export/index.js b/test/configCases/target/system-export/index.js
index 44798c17df8..bfe3bb7e747 100644
--- a/test/configCases/target/system-export/index.js
+++ b/test/configCases/target/system-export/index.js
@@ -1,22 +1,13 @@
 // This test verifies that values exported by a webpack bundle are consumable by systemjs.
 
 export const namedThing = {
-	hello: 'there'
-}
+	hello: "there"
+};
 
-export default 'the default export'
+export default "the default export";
 
-it("should successfully export values to System", function(done) {
-	var fs = require("fs");
-	var source = fs.readFileSync(__filename, "utf-8");
-
-	// set timeout allows the webpack bundle to finish exporting, which exports to System at the very
-	// end of its execution.
-	setTimeout(() => {
-		expect(global.SystemExports['default']).toBe('the default export')
-		expect(global.SystemExports.namedThing).toBe(namedThing)
-		delete global.System;
-		delete global.SystemExports
-		done()
-	})
-});
\ No newline at end of file
+it("should successfully export values to System", function() {
+	const exports = eval("System").registry["(anonym)"].exports;
+	expect(exports["default"]).toBe("the default export");
+	expect(exports.namedThing).toBe(namedThing);
+});
diff --git a/test/configCases/target/system-export/test.config.js b/test/configCases/target/system-export/test.config.js
new file mode 100644
index 00000000000..97ebf538dbe
--- /dev/null
+++ b/test/configCases/target/system-export/test.config.js
@@ -0,0 +1,13 @@
+const System = require("../../../helpers/fakeSystem");
+
+module.exports = {
+	beforeExecute: () => {
+		System.init();
+	},
+	moduleScope(scope) {
+		scope.System = System;
+	},
+	afterExecute: () => {
+		System.execute("(anonym)");
+	}
+};
diff --git a/test/configCases/target/system-export/webpack.config.js b/test/configCases/target/system-export/webpack.config.js
index 2c09f946d53..063b492074e 100644
--- a/test/configCases/target/system-export/webpack.config.js
+++ b/test/configCases/target/system-export/webpack.config.js
@@ -1,4 +1,3 @@
-const webpack = require("../../../../");
 module.exports = {
 	output: {
 		libraryTarget: "system"
@@ -6,23 +5,5 @@ module.exports = {
 	node: {
 		__dirname: false,
 		__filename: false
-	},
-	plugins: [
-		new webpack.BannerPlugin({
-			raw: true,
-			banner: `
-				global.SystemExports = {
-					'export': function(exports) {
-						Object.assign(global.SystemExports, exports);
-					}
-				};
-				global.System = {
-					register: function(deps, fn) {
-						var mod = fn(global.SystemExports['export']);
-						mod.execute();
-					}
-				};
-			`
-		})
-	]
+	}
 };
diff --git a/test/configCases/target/system-named/index.js b/test/configCases/target/system-named/index.js
index 0dafc34d9ce..5f355e1d11f 100644
--- a/test/configCases/target/system-named/index.js
+++ b/test/configCases/target/system-named/index.js
@@ -1,15 +1,5 @@
 /* This test verifies that when output.library is specified that the compiled bundle provides
-* the library name to System during the System.register
-*/
+ * the library name to System during the System.register
+ */
 
-afterEach(function(done) {
-	delete global.System;
-	done()
-})
-
-it("should call System.register with a name", function() {
-	var fs = require("fs");
-	var source = fs.readFileSync(__filename, "utf-8");
-
-	expect(source).toMatch(/.*System\.register\("named-system-module", \[[^\]]*\]/);
-});
\ No newline at end of file
+it("should call System.register with a name", function() {});
diff --git a/test/configCases/target/system-named/test.config.js b/test/configCases/target/system-named/test.config.js
new file mode 100644
index 00000000000..8b3f83a51f9
--- /dev/null
+++ b/test/configCases/target/system-named/test.config.js
@@ -0,0 +1,13 @@
+const System = require("../../../helpers/fakeSystem");
+
+module.exports = {
+	beforeExecute: () => {
+		System.init();
+	},
+	moduleScope(scope) {
+		scope.System = System;
+	},
+	afterExecute: () => {
+		System.execute("named-system-module");
+	}
+};
diff --git a/test/configCases/target/system-named/webpack.config.js b/test/configCases/target/system-named/webpack.config.js
index 838038e8c9c..1f4b76b0ca1 100644
--- a/test/configCases/target/system-named/webpack.config.js
+++ b/test/configCases/target/system-named/webpack.config.js
@@ -1,4 +1,3 @@
-const webpack = require("../../../../");
 module.exports = {
 	output: {
 		library: "named-system-module",
@@ -7,19 +6,5 @@ module.exports = {
 	node: {
 		__dirname: false,
 		__filename: false
-	},
-	plugins: [
-		new webpack.BannerPlugin({
-			raw: true,
-			banner: `
-				System = {
-					register: function(name, deps, fn) {
-						function dynamicExport() {}
-						var mod = fn(dynamicExport);
-						mod.execute();
-					}
-				}
-			`
-		})
-	]
+	}
 };
diff --git a/test/configCases/target/system-unnamed/index.js b/test/configCases/target/system-unnamed/index.js
index 0991f8cda3c..7f2b1a91ee9 100644
--- a/test/configCases/target/system-unnamed/index.js
+++ b/test/configCases/target/system-unnamed/index.js
@@ -1,15 +1,5 @@
 /* This test verifies that when there is no output.library specified that the call to
-* System.register does not include a name argument.
-*/
+ * System.register does not include a name argument.
+ */
 
-afterEach(function(done) {
-	delete global.System;
-	done()
-})
-
-it("should call System.register without a name", function() {
-	var fs = require("fs");
-	var source = fs.readFileSync(__filename, "utf-8");
-
-	expect(source).toMatch(/.*System\.register\(\[[^\]]*\], function\(__WEBPACK_DYNAMIC_EXPORT__\) {\s+(var .*;)?\s*return \{\s+setters: [^]+,[^]+execute: function\(\) {/);
-});
\ No newline at end of file
+it("should call System.register without a name", function() {});
diff --git a/test/configCases/target/system-unnamed/test.config.js b/test/configCases/target/system-unnamed/test.config.js
new file mode 100644
index 00000000000..97ebf538dbe
--- /dev/null
+++ b/test/configCases/target/system-unnamed/test.config.js
@@ -0,0 +1,13 @@
+const System = require("../../../helpers/fakeSystem");
+
+module.exports = {
+	beforeExecute: () => {
+		System.init();
+	},
+	moduleScope(scope) {
+		scope.System = System;
+	},
+	afterExecute: () => {
+		System.execute("(anonym)");
+	}
+};
diff --git a/test/configCases/target/system-unnamed/webpack.config.js b/test/configCases/target/system-unnamed/webpack.config.js
index 41c2d0fcf1a..063b492074e 100644
--- a/test/configCases/target/system-unnamed/webpack.config.js
+++ b/test/configCases/target/system-unnamed/webpack.config.js
@@ -1,4 +1,3 @@
-const webpack = require("../../../../");
 module.exports = {
 	output: {
 		libraryTarget: "system"
@@ -6,20 +5,5 @@ module.exports = {
 	node: {
 		__dirname: false,
 		__filename: false
-	},
-	plugins: [
-		new webpack.BannerPlugin({
-			raw: true,
-			banner: `
-				System = {
-					register: function(deps, fn) {
-						function dynamicExport() {}
-
-						var mod = fn(dynamicExport)
-						mod.execute()
-					}
-				}
-			`
-		})
-	]
+	}
 };
diff --git a/test/helpers/fakeSystem.js b/test/helpers/fakeSystem.js
new file mode 100644
index 00000000000..2b83c4b9341
--- /dev/null
+++ b/test/helpers/fakeSystem.js
@@ -0,0 +1,80 @@
+const System = {
+	register: (name, deps, fn) => {
+		if (!System.registry) {
+			throw new Error("System is no initialized");
+		}
+		if (typeof name !== "string") {
+			fn = deps;
+			deps = name;
+			name = "(anonym)";
+		}
+		if (!Array.isArray(deps)) {
+			fn = deps;
+			deps = [];
+		}
+		const dynamicExport = result => {
+			if (System.registry[name] !== entry) {
+				throw new Error(`Module ${name} calls dynamicExport too late`);
+			}
+			entry.exports = result;
+		};
+		if (name in System.registry) {
+			throw new Error(`Module ${name} is already registered`);
+		}
+		const mod = fn(dynamicExport);
+		if (deps.length > 0) {
+			if (!Array.isArray(mod.setters)) {
+				throw new Error(
+					`Module ${name} must have setters, because it has dependencies`
+				);
+			}
+			if (mod.setters.length !== deps.length) {
+				throw new Error(
+					`Module ${name} has incorrect number of setters for the dependencies`
+				);
+			}
+		}
+		const entry = {
+			name,
+			deps,
+			fn,
+			mod,
+			executed: false,
+			exports: undefined
+		};
+		System.registry[name] = entry;
+	},
+	registry: undefined,
+	init: modules => {
+		System.registry = {};
+		if (modules) {
+			for (const name of Object.keys(modules)) {
+				System.registry[name] = {
+					executed: true,
+					exports: modules[name]
+				};
+			}
+		}
+	},
+	execute: name => {
+		const m = System.registry[name];
+		if (!m) throw new Error(`Module ${name} not registered`);
+		if (m.executed) throw new Error(`Module ${name} was already executed`);
+		return System.ensureExecuted(name);
+	},
+	ensureExecuted: name => {
+		const m = System.registry[name];
+		if (!m) throw new Error(`Module ${name} not registered`);
+		if (!m.executed) {
+			m.executed = true;
+			for (let i = 0; i < m.deps.length; i++) {
+				const dep = m.deps[i];
+				System.ensureExecuted(dep);
+				m.mod.setters[i](System.registry[dep].exports);
+			}
+			m.mod.execute();
+		}
+		return m.exports;
+	}
+};
+module.exports = System;