Remove legacy signature/code for createFetchMiddleware (#402)

Now that `createFetchMiddleware` takes an `RpcService`, there is no need
for it to take its old signature (`fetch`, `btoa`, `rpcUrl`, and
`originHttpHeaderKey`), and there is no need for the old logic (as that
has been integrated into `RpcService`).

Author: mcmire

CHANGELOG.md

@@ -7,6 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- **BREAKING:** `createFetchMiddleware` no longer takes `fetch`, `btoa`, `rpcUrl`, and `originHttpHeaderKey` ([#402](https://github.com/MetaMask/eth-json-rpc-middleware/pull/402))
+  - The existing signature (`rpcService` and `options`) is now the only way to use this function; please use that instead.
+
+### Removed
+
+- **BREAKING:** Remove `PayloadWithOrigin` type ([#402](https://github.com/MetaMask/eth-json-rpc-middleware/pull/402))
+  - There is no equivalent.
+- **BREAKING:** Remove `createFetchConfigFromReq` function ([#402](https://github.com/MetaMask/eth-json-rpc-middleware/pull/402))
+  - There is no equivalent.
+
 ## [17.1.0]
 
 ### Added

src/fetch.test.ts

@@ -1,22 +1,9 @@
 import { JsonRpcEngine } from '@metamask/json-rpc-engine';
 import type { Json, JsonRpcParams, JsonRpcRequest } from '@metamask/utils';
 
-import { createFetchConfigFromReq } from '.';
 import { createFetchMiddleware } from './fetch';
 import type { AbstractRpcService } from './types';
 
-/**
- * Generate a base64-encoded string from a binary string. This should be equivalent to
- * `window.btoa`.
- *
- * @param stringToEncode - The string to encode.
- * @returns The base64-encoded string.
- */
-// eslint-disable-next-line @typescript-eslint/no-shadow
-function btoa(stringToEncode: string) {
-  return Buffer.from(stringToEncode).toString('base64');
-}
-
 describe('createFetchMiddleware', () => {
   it('calls the RPC service with the correct request headers and body when no `originHttpHeaderKey` option given', async () => {
     const rpcService = buildRpcService();
@@ -244,60 +231,6 @@ describe('createFetchMiddleware', () => {
   });
 });
 
-describe('createFetchConfigFromReq', () => {
-  it('should create a fetch config from a request', async () => {
-    const req = {
-      id: 1,
-      jsonrpc: '2.0' as const,
-      method: 'eth_getBlockByNumber',
-      params: ['0x482103', true],
-    };
-    const rpcUrl = 'http://www.xyz.io/rabbit:3456?id=100';
-    const { fetchUrl, fetchParams } = createFetchConfigFromReq({
-      btoa,
-      req,
-      rpcUrl,
-    });
-    expect(fetchUrl).toStrictEqual(rpcUrl);
-    expect(fetchParams).toStrictEqual({
-      method: 'POST',
-      headers: {
-        Accept: 'application/json',
-        'Content-Type': 'application/json',
-      },
-      body: JSON.stringify(req),
-    });
-  });
-
-  it('should create a fetch config with origin header', async () => {
-    const request = {
-      id: 1,
-      jsonrpc: '2.0' as const,
-      method: 'eth_getBlockByNumber',
-      params: ['0x482103', true],
-    };
-    const requestWithOrigin = { ...request, origin: 'happydapp.gov' };
-    const rpcUrl = 'http://www.xyz.io/rabbit:3456?id=100';
-    const originHttpHeaderKey = 'x-dapp-origin';
-    const { fetchUrl, fetchParams } = createFetchConfigFromReq({
-      btoa,
-      req: requestWithOrigin,
-      rpcUrl,
-      originHttpHeaderKey,
-    });
-    expect(fetchUrl).toStrictEqual(rpcUrl);
-    expect(fetchParams).toStrictEqual({
-      method: 'POST',
-      headers: {
-        Accept: 'application/json',
-        'Content-Type': 'application/json',
-        'x-dapp-origin': 'happydapp.gov',
-      },
-      body: JSON.stringify(request),
-    });
-  });
-});
-
 /**
  * Constructs a fake RPC service for use as a failover in tests.
  *