From aefedef97f2e5f5a2dc61234f2f5bb99e197eed1 Mon Sep 17 00:00:00 2001
From: Kirill Fomichev <fanatid@ya.ru>
Date: Mon, 27 Dec 2021 20:16:43 +0300
Subject: [PATCH 1/4] web3.js: add Connection.getFeeForMessage

---
 web3.js/src/connection.ts       | 18 ++++++++++++++++++
 web3.js/test/connection.test.ts | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/web3.js/src/connection.ts b/web3.js/src/connection.ts
index dd4b592d8bc742..edd9e56855eb44 100644
--- a/web3.js/src/connection.ts
+++ b/web3.js/src/connection.ts
@@ -2998,6 +2998,24 @@ export class Connection {
     };
   }
 
+  /**
+   * Fetch the fee for a message from the cluster, return with context
+   */
+  async getFeeForMessage(
+    message: Message,
+    commitment?: Commitment,
+  ): Promise<RpcResponseAndContext<number | null>> {
+    const wireMessage = message.serialize().toString('base64');
+    const args = this._buildArgs([wireMessage], commitment);
+    const unsafeRes = await this._rpcRequest('getFeeForMessage', args);
+
+    const res = create(unsafeRes, jsonRpcResultAndContext(nullable(number())));
+    if ('error' in res) {
+      throw new Error('failed to get slot: ' + res.error.message);
+    }
+    return res.result;
+  }
+
   /**
    * Fetch a recent blockhash from the cluster
    * @return {Promise<{blockhash: Blockhash, feeCalculator: FeeCalculator}>}
diff --git a/web3.js/test/connection.test.ts b/web3.js/test/connection.test.ts
index 958eb298dc7a63..e34ccc0f953d26 100644
--- a/web3.js/test/connection.test.ts
+++ b/web3.js/test/connection.test.ts
@@ -2278,6 +2278,38 @@ describe('Connection', () => {
     expect(feeCalculator.lamportsPerSignature).to.eq(5000);
   });
 
+  it('get fee for message', async () => {
+    const accountFrom = Keypair.generate();
+    const accountTo = Keypair.generate();
+
+    const {blockhash} = await helpers.recentBlockhash({connection});
+
+    const transaction = new Transaction({
+      feePayer: accountFrom.publicKey,
+      recentBlockhash: blockhash,
+    }).add(
+      SystemProgram.transfer({
+        fromPubkey: accountFrom.publicKey,
+        toPubkey: accountTo.publicKey,
+        lamports: 10,
+      }),
+    );
+    const message = transaction.compileMessage();
+
+    await mockRpcResponse({
+      method: 'getFeeForMessage',
+      params: [
+        message.serialize().toString('base64'),
+        {commitment: 'confirmed'},
+      ],
+      value: 5000,
+      withContext: true,
+    });
+
+    const fee = (await connection.getFeeForMessage(message, 'confirmed')).value;
+    expect(fee).to.eq(5000);
+  });
+
   it('get block time', async () => {
     await mockRpcResponse({
       method: 'getBlockTime',

From 1362356b46723e1594e650966adf125320157829 Mon Sep 17 00:00:00 2001
From: Kirill Fomichev <fanatid@ya.ru>
Date: Mon, 10 Jan 2022 18:44:24 +0300
Subject: [PATCH 2/4] throw if value is null

---
 web3.js/src/connection.ts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/web3.js/src/connection.ts b/web3.js/src/connection.ts
index edd9e56855eb44..8a0b28472e8a15 100644
--- a/web3.js/src/connection.ts
+++ b/web3.js/src/connection.ts
@@ -3013,6 +3013,9 @@ export class Connection {
     if ('error' in res) {
       throw new Error('failed to get slot: ' + res.error.message);
     }
+    if (res.value === null) {
+      throw new Error('invalid blockhash');
+    }
     return res.result;
   }
 

From 851b1d5172ef45630aff96fc0d7f7cceec95f78f Mon Sep 17 00:00:00 2001
From: Kirill Fomichev <fanatid@ya.ru>
Date: Tue, 11 Jan 2022 12:03:23 +0300
Subject: [PATCH 3/4] fix null value

---
 web3.js/src/connection.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/web3.js/src/connection.ts b/web3.js/src/connection.ts
index 8a0b28472e8a15..c8f79a5e0512b1 100644
--- a/web3.js/src/connection.ts
+++ b/web3.js/src/connection.ts
@@ -3004,7 +3004,7 @@ export class Connection {
   async getFeeForMessage(
     message: Message,
     commitment?: Commitment,
-  ): Promise<RpcResponseAndContext<number | null>> {
+  ): Promise<RpcResponseAndContext<number>> {
     const wireMessage = message.serialize().toString('base64');
     const args = this._buildArgs([wireMessage], commitment);
     const unsafeRes = await this._rpcRequest('getFeeForMessage', args);
@@ -3013,7 +3013,7 @@ export class Connection {
     if ('error' in res) {
       throw new Error('failed to get slot: ' + res.error.message);
     }
-    if (res.value === null) {
+    if (res.result === null) {
       throw new Error('invalid blockhash');
     }
     return res.result;

From 481eeb9447d2570d293f91ad7f5cf665389f2a42 Mon Sep 17 00:00:00 2001
From: Kirill Fomichev <fanatid@ya.ru>
Date: Tue, 11 Jan 2022 12:37:55 +0300
Subject: [PATCH 4/4] fix types

---
 web3.js/src/connection.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/web3.js/src/connection.ts b/web3.js/src/connection.ts
index c8f79a5e0512b1..583aaefc324396 100644
--- a/web3.js/src/connection.ts
+++ b/web3.js/src/connection.ts
@@ -3016,7 +3016,7 @@ export class Connection {
     if (res.result === null) {
       throw new Error('invalid blockhash');
     }
-    return res.result;
+    return res.result as unknown as RpcResponseAndContext<number>;
   }
 
   /**