add test case

packages/tx/src/__tests__/gas.spec.ts

@@ -660,6 +660,129 @@ describe("getGasFeeAmount", () => {
     expect(gasAmount.isNeededForTx).toBe(false);
   });
 
+  it("should the correct gas amount with an alternative fee token that is the lesser of the spent amounts", async () => {
+    const gasLimit = 1000;
+    const chainId = "osmosis-1";
+    const address = "osmo1...";
+    const baseFee = 0.04655;
+    const altTokenSpotPrice = 1;
+
+    (queryBalances as jest.Mock).mockResolvedValue({
+      balances: [
+        {
+          denom: "uosmo",
+          amount: "1",
+        },
+        {
+          // ATOM
+          denom:
+            "ibc/27394FB092D2ECCD56123C74F36E4C1F926001CEADA9CA97EA622B25F41E5EB2",
+          amount: "1000",
+        },
+        {
+          denom: "uion",
+          amount: "1000000",
+        },
+      ],
+    } as Awaited<ReturnType<typeof queryBalances>>);
+    (queryFeesBaseGasPrice as jest.Mock).mockResolvedValue({
+      base_fee: baseFee.toString(),
+    } as Awaited<ReturnType<typeof queryFeesBaseGasPrice>>);
+    (queryFeeTokens as jest.Mock).mockResolvedValue({
+      fee_tokens: [
+        {
+          // ATOM
+          denom:
+            "ibc/27394FB092D2ECCD56123C74F36E4C1F926001CEADA9CA97EA622B25F41E5EB2",
+          poolID: 1,
+        },
+        {
+          denom: "uion",
+          poolID: 2,
+        },
+      ],
+    } as Awaited<ReturnType<typeof queryFeeTokens>>);
+    (queryFeesBaseDenom as jest.Mock).mockResolvedValue({
+      base_denom: "uosmo",
+    } as Awaited<ReturnType<typeof queryFeesBaseDenom>>);
+    (queryFeeTokenSpotPrice as jest.Mock).mockImplementation(({ denom }) => {
+      // return the same spot price to isolate the differences in amounts
+      if (
+        denom === "uion" ||
+        denom ===
+          "ibc/27394FB092D2ECCD56123C74F36E4C1F926001CEADA9CA97EA622B25F41E5EB2"
+      ) {
+        return Promise.resolve({
+          pool_id: "2",
+          spot_price: altTokenSpotPrice.toString(),
+        } as Awaited<ReturnType<typeof queryFeeTokenSpotPrice>>);
+      }
+      throw new Error("Mocked implementation got an unexpected fee denom");
+    });
+
+    const gasMultiplier = 1.5;
+    const coinsSpent = [
+      { denom: "uion", amount: "1000" },
+      {
+        // notice smaller amount is second
+        denom:
+          "ibc/27394FB092D2ECCD56123C74F36E4C1F926001CEADA9CA97EA622B25F41E5EB2",
+        amount: "100",
+      },
+    ];
+
+    const gasAmount = (
+      await getGasFeeAmount({
+        chainId,
+        chainList: MockChains,
+        gasLimit: gasLimit.toString(),
+        bech32Address: address,
+        gasMultiplier,
+        coinsSpent,
+      })
+    )[0];
+
+    const expectedGasAmount = new Dec(baseFee * gasMultiplier)
+      .quo(new Dec(altTokenSpotPrice))
+      .mul(new Dec(1.01))
+      .mul(new Dec(gasLimit))
+      .truncate()
+      .toString();
+
+    expect(queryBalances).toBeCalledWith({
+      chainId,
+      bech32Address: address,
+      chainList: MockChains,
+    });
+    expect(queryFeesBaseGasPrice).toBeCalledWith({
+      chainId,
+      chainList: MockChains,
+    });
+    expect(queryFeeTokens).toBeCalledWith({
+      chainId,
+      chainList: MockChains,
+    });
+    expect(queryFeesBaseDenom).toBeCalledWith({
+      chainId,
+      chainList: MockChains,
+    });
+    expect(queryFeeTokenSpotPrice).toBeCalledWith({
+      chainId,
+      chainList: MockChains,
+      denom: "uion",
+    });
+    expect(queryFeeTokenSpotPrice).toBeCalledWith({
+      chainId,
+      chainList: MockChains,
+      denom:
+        "ibc/27394FB092D2ECCD56123C74F36E4C1F926001CEADA9CA97EA622B25F41E5EB2",
+    });
+
+    expect(gasAmount.denom).toBe("uion");
+    expect(gasAmount.amount).toBe(expectedGasAmount);
+    expect(gasAmount.isNeededForTx).toBe(false);
+  });
+
   it("should throw InsufficientFeeError when balance is insufficient without Osmosis fee module — no balances", async () => {
     const gasLimit = 1000;
     const chainId = "cosmoshub-4";