add test for exit status when encountering child compilation error

test/binCases/errors/child-compilation-error/test.js

@@ -0,0 +1,13 @@
+"use strict";
+
+module.exports = function testAssertions(code, stdout, stderr) {
+    code.should.be.eql(2);
+
+	stdout[0].should.containEql("Hash: ");
+	stdout[1].should.containEql("Version: ");
+	stdout[2].should.containEql("Time: ");
+	stdout[5].should.containEql("./index.js");
+	stdout[8].should.containEql("ERROR in child compilation");
+
+	stderr.should.be.empty();
+};

test/binCases/errors/child-compilation-error/webpack.config.js

@@ -0,0 +1,19 @@
+"use strict";
+
+module.exports = {
+	entry: "./index",
+	output: {
+		filename: "bundle.js"
+	},
+	plugins: [{
+        apply(compiler) {
+            compiler.plugin("make", (compilation, cb) => {
+                const child = compilation.createChildCompiler("child", {});
+                child.plugin("compilation", childCompilation => {
+                    childCompilation.errors.push(new Error("child compilation"));
+                });
+                child.runAsChild(cb);
+            });
+        }
+    }]
+};