From afa7351ea53d1b2b4044bf8841a3f61be04f4f1d Mon Sep 17 00:00:00 2001
From: Elliot Winkler <elliot.winkler@gmail.com>
Date: Fri, 30 Sep 2022 16:14:04 -0600
Subject: [PATCH] Align Provider type w/ other packages & re-expose

The Provider type which is used internally by this package is not
compatible with the SafeEventEmitterProvider type used by
`eth-json-rpc-middleware`. This means that whenever using this package
with `eth-json-rpc-middleware` we have to resort to the following
hackery:

```
import { PollingBlockTracker, Provider } from 'eth-block-tracker';
import { JsonRpcEngine } from 'json-rpc-engine';
import { providerFromEngine } from '../src';

const engine = new JsonRpcEngine();
const provider = providerFromEngine(engine);

const blockTracker = new PollingBlockTracker({
  // Notice the typecasting here
  provider: provider as Provider,
});
```

SafeEventEmitterProvider is the more accurate type here in this case,
because it correctly types the `error` argument for the callback that
`sendAsync` calls as `unknown` rather than `Error`, so we follow suit
here.

Additionally, this package used to expose the Provider type and that was
changed in 6.0.0 without being documented, probably because it was
located in the same file as BaseBlockTracker. So here we move the type
to a more obvious place and re-expose it.
---
 src/BaseBlockTracker.ts      |  8 --------
 src/PollingBlockTracker.ts   |  3 ++-
 src/SubscribeBlockTracker.ts |  3 ++-
 src/index.ts                 |  1 +
 src/types.ts                 | 11 +++++++++++
 tests/withBlockTracker.ts    | 10 ++++------
 6 files changed, 20 insertions(+), 16 deletions(-)
 create mode 100644 src/types.ts

diff --git a/src/BaseBlockTracker.ts b/src/BaseBlockTracker.ts
index bd7b9903..4a2e71c1 100644
--- a/src/BaseBlockTracker.ts
+++ b/src/BaseBlockTracker.ts
@@ -1,5 +1,4 @@
 import SafeEventEmitter from '@metamask/safe-event-emitter';
-import { JsonRpcRequest, JsonRpcResponse } from 'json-rpc-engine';
 
 const sec = 1000;
 
@@ -7,13 +6,6 @@ const calculateSum = (accumulator: number, currentValue: number) =>
   accumulator + currentValue;
 const blockTrackerEvents: (string | symbol)[] = ['sync', 'latest'];
 
-export interface Provider extends SafeEventEmitter {
-  sendAsync: <T, U>(
-    req: JsonRpcRequest<T>,
-    cb: (err: Error, response: JsonRpcResponse<U>) => void,
-  ) => void;
-}
-
 interface BaseBlockTrackerArgs {
   blockResetDuration?: number;
 }
diff --git a/src/PollingBlockTracker.ts b/src/PollingBlockTracker.ts
index 48bbb737..34f9bfbe 100644
--- a/src/PollingBlockTracker.ts
+++ b/src/PollingBlockTracker.ts
@@ -1,8 +1,9 @@
 import getCreateRandomId from 'json-rpc-random-id';
 import pify from 'pify';
 import { JsonRpcRequest } from 'json-rpc-engine';
-import { BaseBlockTracker, Provider } from './BaseBlockTracker';
+import { BaseBlockTracker } from './BaseBlockTracker';
 import { projectLogger, createModuleLogger } from './logging-utils';
+import { Provider } from './types';
 
 const log = createModuleLogger(projectLogger, 'polling-block-tracker');
 const createRandomId = getCreateRandomId();
diff --git a/src/SubscribeBlockTracker.ts b/src/SubscribeBlockTracker.ts
index 039f5dd6..86958be2 100644
--- a/src/SubscribeBlockTracker.ts
+++ b/src/SubscribeBlockTracker.ts
@@ -1,6 +1,7 @@
 import getCreateRandomId from 'json-rpc-random-id';
 import { JsonRpcNotification, JsonRpcSuccess } from 'json-rpc-engine';
-import { BaseBlockTracker, Provider } from './BaseBlockTracker';
+import { BaseBlockTracker } from './BaseBlockTracker';
+import { Provider } from './types';
 
 const createRandomId = getCreateRandomId();
 
diff --git a/src/index.ts b/src/index.ts
index 11e7924f..53bc3052 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,2 +1,3 @@
 export * from './PollingBlockTracker';
 export * from './SubscribeBlockTracker';
+export * from './types';
diff --git a/src/types.ts b/src/types.ts
new file mode 100644
index 00000000..55a89568
--- /dev/null
+++ b/src/types.ts
@@ -0,0 +1,11 @@
+import SafeEventEmitter from '@metamask/safe-event-emitter';
+import { JsonRpcRequest, JsonRpcResponse } from 'json-rpc-engine';
+
+// This type should be compatible with the one defined in
+// `eth-json-rpc-middleware`.
+export interface Provider extends SafeEventEmitter {
+  sendAsync: <T, U>(
+    req: JsonRpcRequest<T>,
+    cb: (err: unknown, response: JsonRpcResponse<U>) => void,
+  ) => void;
+}
diff --git a/tests/withBlockTracker.ts b/tests/withBlockTracker.ts
index 439c47ee..9aa379b9 100644
--- a/tests/withBlockTracker.ts
+++ b/tests/withBlockTracker.ts
@@ -1,15 +1,13 @@
 import util from 'util';
 import SafeEventEmitter from '@metamask/safe-event-emitter';
 import { JsonRpcRequest, JsonRpcResponse } from 'json-rpc-engine';
-import { Provider } from '../src/BaseBlockTracker';
-import {
-  SubscribeBlockTracker,
-  SubscribeBlockTrackerOptions,
-} from '../src/SubscribeBlockTracker';
 import {
   PollingBlockTracker,
   PollingBlockTrackerOptions,
-} from '../src/PollingBlockTracker';
+  Provider,
+  SubscribeBlockTracker,
+  SubscribeBlockTrackerOptions,
+} from '../src';
 
 interface WithPollingBlockTrackerOptions {
   provider?: FakeProviderOptions;