fix: apply header only in node (#582)

Author: Chase Coalwell

packages/middleware-expect-continue/src/index.spec.ts

@@ -8,8 +8,11 @@ describe("addExpectContinueMiddleware", () => {
     jest.clearAllMocks();
   });
 
-  it("sets the Expect header to 100-continue if there is a request body", async () => {
-    const handler = addExpectContinueMiddleware()(mockNextHandler, {} as any);
+  it("sets the Expect header to 100-continue if there is a request body in node runtime", async () => {
+    const handler = addExpectContinueMiddleware({ runtime: "node" })(
+      mockNextHandler,
+      {} as any
+    );
     await handler({
       input: {},
       request: new HttpRequest({
@@ -24,8 +27,11 @@ describe("addExpectContinueMiddleware", () => {
     expect(request.headers["Expect"]).toBe("100-continue");
   });
 
-  it("does not set the Expect header to 100-continue if there is no request body", async () => {
-    const handler = addExpectContinueMiddleware()(mockNextHandler, {} as any);
+  it("does not set the Expect header to 100-continue if there is no request body in node runtime", async () => {
+    const handler = addExpectContinueMiddleware({ runtime: "node" })(
+      mockNextHandler,
+      {} as any
+    );
     await handler({
       input: {},
       request: new HttpRequest({
@@ -38,4 +44,23 @@ describe("addExpectContinueMiddleware", () => {
     const { request } = mockNextHandler.mock.calls[0][0];
     expect(request.headers["Expect"]).toBeUndefined();
   });
+
+  it("does not set the Expect header to 100-continue for browser runtime", async () => {
+    const handler = addExpectContinueMiddleware({ runtime: "browser" })(
+      mockNextHandler,
+      {} as any
+    );
+    await handler({
+      input: {},
+      request: new HttpRequest({
+        body: "foo",
+        headers: {}
+      })
+    });
+
+    const { calls } = (mockNextHandler as any).mock;
+    expect(calls.length).toBe(1);
+    const { request } = mockNextHandler.mock.calls[0][0];
+    expect(request.headers["Expect"]).toBeUndefined();
+  });
 });

packages/middleware-expect-continue/src/index.ts

@@ -9,14 +9,24 @@ import {
 } from "@aws-sdk/types";
 import { HttpRequest } from "@aws-sdk/protocol-http";
 
-export function addExpectContinueMiddleware(): BuildMiddleware<any, any> {
+interface PreviouslyResolved {
+  runtime: string;
+}
+
+export function addExpectContinueMiddleware(
+  options: PreviouslyResolved
+): BuildMiddleware<any, any> {
   return <Output extends MetadataBearer>(
     next: BuildHandler<any, Output>
   ): BuildHandler<any, Output> => async (
     args: BuildHandlerArguments<any>
   ): Promise<BuildHandlerOutput<Output>> => {
     let { request } = args;
-    if (HttpRequest.isInstance(request) && request.body) {
+    if (
+      HttpRequest.isInstance(request) &&
+      request.body &&
+      options.runtime === "node"
+    ) {
       request.headers = {
         ...request.headers,
         Expect: "100-continue"
@@ -36,11 +46,11 @@ export const addExpectContinueMiddlewareOptions: BuildHandlerOptions = {
 };
 
 export const getAddExpectContinuePlugin = (
-  unused: any
+  options: PreviouslyResolved
 ): Pluggable<any, any> => ({
   applyToStack: clientStack => {
     clientStack.add(
-      addExpectContinueMiddleware(),
+      addExpectContinueMiddleware(options),
       addExpectContinueMiddlewareOptions
     );
   }