Gas price method added to provider (#521)

gas price method added to the provider

src/providers/json-rpc-provider.ts

@@ -2,7 +2,7 @@ import depd from 'depd';
 import {
     Provider, FinalExecutionOutcome, NodeStatusResult, BlockId, Finality,
     BlockResult, ChunkId, ChunkResult, EpochValidatorInfo,
-    GenesisConfig, LightClientProof, LightClientProofRequest
+    GenesisConfig, LightClientProof, LightClientProofRequest, GasPrice
 } from './provider';
 import { Network } from '../utils/network';
 import { ConnectionInfo, fetchJson } from '../utils/web';
@@ -209,4 +209,13 @@ export class JsonRpcProvider extends Provider {
         }
         return result;
     }
+
+    /**
+     * Returns gas price for a specific block_height or block_hash.
+     * See [docs for more info](https://docs.near.org/docs/develop/front-end/rpc#gas-price)
+     * @param blockId Block hash or height, or null for latest.
+     */
+    async gasPrice(blockId: BlockId | null): Promise<GasPrice> {
+        return await this.sendJsonRpc('gas_price', [blockId]);
+    }
 }

src/providers/provider.ts

@@ -235,6 +235,10 @@ export interface LightClientProofRequest {
     receiver_id?: string;
 }
 
+export interface GasPrice {
+    gas_price: string;
+}
+
 export abstract class Provider {
     abstract getNetwork(): Promise<Network>;
     abstract status(): Promise<NodeStatusResult>;
@@ -250,6 +254,7 @@ export abstract class Provider {
     abstract validators(blockId: BlockId): Promise<EpochValidatorInfo>;
     abstract experimental_genesisConfig(): Promise<GenesisConfig>;
     abstract lightClientProof(request: LightClientProofRequest): Promise<LightClientProof>;
+    abstract gasPrice(blockId: BlockId): Promise<GasPrice>
 }
 
 export function getTransactionLastResult(txResult: FinalExecutionOutcome): any {

test/providers.test.js

@@ -144,3 +144,17 @@ test('json rpc light client proof', async() => {
 
     await expect(provider.lightClientProof(lightClientRequest)).rejects.toThrow(/.+ block .+ is ahead of head block .+/);
 });
+
+test('json rpc gas price', withProvider(async (provider) => {
+    let status = await provider.status();
+    let positiveIntegerRegex = /^[+]?\d+([.]\d+)?$/;
+
+    let response1 = await provider.gasPrice(status.sync_info.latest_block_height);
+    expect(response1.gas_price).toMatch(positiveIntegerRegex);
+
+    let response2 = await provider.gasPrice(status.sync_info.latest_block_hash);
+    expect(response2.gas_price).toMatch(positiveIntegerRegex);
+
+    let response3 = await provider.gasPrice();
+    expect(response3.gas_price).toMatch(positiveIntegerRegex);
+}));