feat: dummy pricing provider (#58)

# 🤖 Linear

Closes ZKS-212

## Description

Implement DummyPricingProvider
- return fixed price of 1 for every token
- to be used in testnet or local

packages/pricing/src/external.ts

@@ -2,4 +2,4 @@ export type { IPricingProvider, PriceResponse } from "./internal.js";
 
 export { RateLimitExceeded, ApiNotAvailable } from "./internal.js";
 
-export { CoingeckoProvider } from "./internal.js";
+export { CoingeckoProvider, DummyPricingProvider } from "./internal.js";

packages/pricing/src/providers/dummy.provider.ts

@@ -0,0 +1,13 @@
+import { Address } from "@zkchainhub/shared";
+
+import { IPricingProvider, PriceResponse } from "../internal.js";
+
+/**
+ * DummyPricingProvider class that implements the IPricingProvider interface.
+ * This provider returns a fixed price of 1 for each token address.
+ */
+export class DummyPricingProvider implements IPricingProvider {
+    async getTokenPrices(addresses: Address[]): Promise<PriceResponse> {
+        return Promise.resolve(Object.fromEntries(addresses.map((address) => [address, 1])));
+    }
+}

packages/pricing/src/providers/index.ts

@@ -1 +1,2 @@
 export * from "./coingecko.provider.js";
+export * from "./dummy.provider.js";

packages/pricing/test/unit/services/dummy.provider.spec.ts

@@ -0,0 +1,25 @@
+import { beforeEach, describe, expect, it } from "vitest";
+
+import { Address } from "@zkchainhub/shared";
+
+import { DummyPricingProvider } from "../../../src/providers/dummy.provider.js";
+
+describe("DummyPricingProvider", () => {
+    let provider: DummyPricingProvider;
+
+    beforeEach(() => {
+        provider = new DummyPricingProvider();
+    });
+
+    it("return 1 for all token prices", async () => {
+        const addresses: Address[] = ["0x123456789", "0xabcdef123"];
+        const expectedResponse = {
+            "0x123456789": 1,
+            "0xabcdef123": 1,
+        };
+
+        const response = await provider.getTokenPrices(addresses);
+
+        expect(response).toEqual(expectedResponse);
+    });
+});