feat: support callback signature for fallback gas price option

lib/networks/__tests__/getEthereumGasPrice.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect } from "vitest";
+import { describe, it, expect, vi } from "vitest";
 
 import { mockFetch } from "./mockFetch";
 
@@ -282,4 +282,75 @@ describe("getEthereumGasPrice", () => {
       },
     });
   });
+  it("should return the fallback gas price function return value if there an issue fetching from the Ethereum gas station", async () => {
+    mockFetch(undefined, { ok: false });
+
+    const gasPrice = 100;
+
+    const fallbackGasPrice = vi.fn(async () => {
+      return gasPrice;
+    });
+
+    const withFallbackFunctionValue = await getEthereumGasPrice("ethereum", {
+      fallbackGasPrice,
+    });
+
+    expect(fallbackGasPrice).toHaveBeenCalledTimes(1);
+
+    expect(withFallbackFunctionValue).toEqual({
+      low: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      average: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      high: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      asap: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+    });
+  });
+  it("should return the fallback gas price function return value if there an error fetching from the Ethereum gas station", async () => {
+    mockFetch({
+      status: "0",
+      result: "Some error",
+    });
+
+    const gasPrice = 100;
+
+    const fallbackGasPrice = vi.fn(async () => {
+      return gasPrice;
+    });
+
+    const withFallbackFunctionValue = await getEthereumGasPrice("ethereum", {
+      fallbackGasPrice,
+    });
+
+    expect(fallbackGasPrice).toHaveBeenCalledTimes(1);
+
+    expect(withFallbackFunctionValue).toEqual({
+      low: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      average: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      high: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      asap: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+    });
+  });
 });

lib/networks/__tests__/getPolygonGasPrice.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect } from "vitest";
+import { describe, it, expect, vi } from "vitest";
 
 import { mockFetch } from "./mockFetch";
 
@@ -139,4 +139,38 @@ describe("getPolygonGasPrice", () => {
       },
     });
   });
+  it("should return the fallback gas price function return value if there an issue fetching from the Polygon gas station", async () => {
+    mockFetch(undefined, { ok: false });
+
+    const gasPrice = 100;
+
+    const fallbackGasPrice = vi.fn(async () => {
+      return gasPrice;
+    });
+
+    const withFallbackFunctionValue = await getPolygonGasPrice("polygon", {
+      fallbackGasPrice,
+    });
+
+    expect(fallbackGasPrice).toHaveBeenCalledTimes(1);
+
+    expect(withFallbackFunctionValue).toEqual({
+      low: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      average: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      high: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+      asap: {
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
+      },
+    });
+  });
 });

lib/networks/getEthereumGasPrice.ts

@@ -28,7 +28,7 @@ interface ResponseEthereumGasPrice {
 
 interface EthereumOptions {
   apiKey?: string;
-  fallbackGasPrice?: number;
+  fallbackGasPrice?: number | (() => Promise<number>);
 }
 
 export async function getEthereumGasPrice(
@@ -94,22 +94,27 @@ export async function getEthereumGasPrice(
       asap: asapGasPriceLevel,
     };
   } catch (error) {
+    const gasPrice =
+      typeof fallbackGasPrice === "function"
+        ? await fallbackGasPrice()
+        : fallbackGasPrice;
+
     return {
       low: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
       average: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
       high: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
       asap: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
     };
   }

lib/networks/getPolygonGasPrice.ts

@@ -27,7 +27,7 @@ interface ResponsePolygonGasPrice {
 }
 
 interface PolygonOptions {
-  fallbackGasPrice?: number;
+  fallbackGasPrice?: number | (() => Promise<number>);
 }
 
 export async function getPolygonGasPrice(
@@ -66,22 +66,27 @@ export async function getPolygonGasPrice(
       asap: asapGasPriceLevel,
     };
   } catch (error) {
+    const gasPrice =
+      typeof fallbackGasPrice === "function"
+        ? await fallbackGasPrice()
+        : fallbackGasPrice;
+
     return {
       low: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
       average: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
       high: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
       asap: {
-        maxPriorityFeePerGas: fallbackGasPrice,
-        maxFeePerGas: fallbackGasPrice,
+        maxPriorityFeePerGas: gasPrice,
+        maxFeePerGas: gasPrice,
       },
     };
   }

lib/types.ts

@@ -17,5 +17,5 @@ export interface GasPrice {
 
 export interface Options {
   etherscanApiKey?: string;
-  fallbackGasPrice?: Partial<Record<Network, number>>;
+  fallbackGasPrice?: Partial<Record<Network, number | (() => Promise<number>)>>;
 }