diff --git a/contracts/DODOVendingMachine/impl/DVM.sol b/contracts/DODOVendingMachine/impl/DVM.sol
index 5f95151..8d353e9 100644
--- a/contracts/DODOVendingMachine/impl/DVM.sol
+++ b/contracts/DODOVendingMachine/impl/DVM.sol
@@ -38,6 +38,8 @@ contract DVM is DVMTrader, DVMFunding {
         _GAS_PRICE_LIMIT_ = IExternalValue(gasPriceSource);
         _MAINTAINER_ = maintainer;
         _I_ = i;
+
+        require(k > 0 && k <= 10**18);
         _K_ = k;
 
         string memory connect = "_";
diff --git a/test/DVM/AMMLikeCase.test.ts b/test/DVM/AMMLikeCase.test.ts
new file mode 100644
index 0000000..01c6f98
--- /dev/null
+++ b/test/DVM/AMMLikeCase.test.ts
@@ -0,0 +1,162 @@
+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+// import * as assert from 'assert';
+
+import { decimalStr, gweiStr } from '../utils/Converter';
+import { logGas } from '../utils/Log';
+import { DVMContext, getDVMContext } from '../utils/DVMContext';
+import { assert } from 'chai';
+
+let lp: string;
+let trader: string;
+
+async function init(ctx: DVMContext): Promise<void> {
+  lp = ctx.SpareAccounts[0];
+  trader = ctx.SpareAccounts[1];
+  await ctx.approveProxy(lp);
+  await ctx.approveProxy(trader);
+
+  await ctx.mintTestToken(lp, decimalStr("10"), decimalStr("1000"));
+  await ctx.mintTestToken(trader, decimalStr("10"), decimalStr("1000"));
+
+  await ctx.DVMProxy.methods
+    .depositToDVM(ctx.DVM.options.address, lp, decimalStr("10"), decimalStr("1000"))
+    .send(ctx.sendParam(lp));
+
+  console.log("deposit")
+}
+
+describe("AMMLikeCase", () => {
+  let snapshotId: string;
+  let ctx: DVMContext;
+
+  before(async () => {
+    let AMMLikeDVMContextInitConfig = {
+      lpFeeRate: decimalStr("0.002"),
+      mtFeeRate: decimalStr("0.001"),
+      k: decimalStr("1"),
+      i: "1",
+    };
+    ctx = await getDVMContext(AMMLikeDVMContextInitConfig);
+    await init(ctx);
+  });
+
+  beforeEach(async () => {
+    snapshotId = await ctx.EVM.snapshot();
+  });
+
+  afterEach(async () => {
+    await ctx.EVM.reset(snapshotId);
+  });
+
+  describe("trade", () => {
+
+    it("basic state", async () => {
+      console.log(await ctx.DVM.methods.getMidPrice().call())
+      console.log(await ctx.DVM.methods.getBase0().call())
+    })
+
+    it("buy & sell", async () => {
+
+      console.log("BASE0 before buy", await ctx.DVM.methods.getBase0().call())
+
+      // buy
+      await logGas(ctx.DVMProxy.methods.sellQuoteOnDVM(ctx.DVM.options.address, trader, decimalStr("200"), decimalStr("1")), ctx.sendParam(trader), "buy base token")
+      console.log("BASE0 after buy", await ctx.DVM.methods.getBase0().call())
+      // trader balances
+      console.log(
+        await ctx.BASE.methods.balanceOf(trader).call(),
+        "11946763594380080787"
+      );
+      console.log(
+        await ctx.QUOTE.methods.balanceOf(trader).call(),
+        decimalStr("800")
+      );
+      // vault balances
+      console.log(
+        await ctx.BASE.methods.balanceOf(ctx.DVM.options.address).call(),
+        "8051283784161162863"
+      );
+      console.log(
+        await ctx.QUOTE.methods.balanceOf(ctx.DVM.options.address).call(),
+        decimalStr("200")
+      );
+      // maintainer balances
+      console.log(
+        await ctx.BASE.methods.balanceOf(ctx.Maintainer).call(),
+        "1952621458756350"
+      );
+      console.log(
+        await ctx.QUOTE.methods.balanceOf(ctx.Maintainer).call(),
+        decimalStr("0")
+      );
+
+      // // sell
+      // await logGas(ctx.DVMProxy.methods.sellBaseOnDVM(ctx.DVM.options.address, trader, decimalStr("1"), decimalStr("100")), ctx.sendParam(trader), "sell base token")
+      // console.log("BASE0 after sell", await ctx.DVM.methods.getBase0().call())
+      // // trader balances
+      // assert.equal(
+      //   await ctx.BASE.methods.balanceOf(trader).call(),
+      //   "10946763594380080787"
+      // );
+      // assert.equal(
+      //   await ctx.QUOTE.methods.balanceOf(trader).call(),
+      //   "903421810640399874603"
+      // );
+      // // vault balances
+      // assert.equal(
+      //   await ctx.BASE.methods.balanceOf(ctx.DVM.options.address).call(),
+      //   "9051283784161162863"
+      // );
+      // assert.equal(
+      //   await ctx.QUOTE.methods.balanceOf(ctx.DVM.options.address).call(),
+      //   "96474456349930717298"
+      // );
+      // // maintainer balances
+      // assert.equal(
+      //   await ctx.BASE.methods.balanceOf(ctx.Maintainer).call(),
+      //   "1952621458756350"
+      // );
+      // assert.equal(
+      //   await ctx.QUOTE.methods.balanceOf(ctx.Maintainer).call(),
+      //   "103733009669408099"
+      // );
+
+      // // buy when quoet is not 0
+      // await logGas(ctx.DVMProxy.methods.sellQuoteOnDVM(ctx.DVM.options.address, trader, decimalStr("200"), decimalStr("1")), ctx.sendParam(trader), "buy base token")
+      // assert.equal("BASE0 after second buy", await ctx.DVM.methods.getBase0().call())
+      // // trader balances
+      // assert.equal(
+      //   await ctx.BASE.methods.balanceOf(trader).call(),
+      //   "12837528824326616018"
+      // );
+      // assert.equal(
+      //   await ctx.QUOTE.methods.balanceOf(trader).call(),
+      //   "703421810640399874603"
+      // );
+      // // vault balances
+      // assert.equal(
+      //   await ctx.BASE.methods.balanceOf(ctx.DVM.options.address).call(),
+      //   "7158622099620899913"
+      // );
+      // assert.equal(
+      //   await ctx.QUOTE.methods.balanceOf(ctx.DVM.options.address).call(),
+      //   "296474456349930717298"
+      // );
+      // // maintainer balances
+      // assert.equal(
+      //   await ctx.BASE.methods.balanceOf(ctx.Maintainer).call(),
+      //   "3849076052484069"
+      // );
+      // assert.equal(
+      //   await ctx.QUOTE.methods.balanceOf(ctx.Maintainer).call(),
+      //   "103733009669408099"
+      // );
+    });
+  });
+});
diff --git a/test/DVM/trader.test.ts b/test/DVM/trader.test.ts
index 4cce507..d9cba34 100644
--- a/test/DVM/trader.test.ts
+++ b/test/DVM/trader.test.ts
@@ -7,7 +7,7 @@
 
 // import * as assert from 'assert';
 
-import { decimalStr } from '../utils/Converter';
+import { decimalStr, gweiStr } from '../utils/Converter';
 import { logGas } from '../utils/Log';
 import { DVMContext, getDVMContext } from '../utils/DVMContext';
 import { assert } from 'chai';
@@ -49,12 +49,13 @@ describe("Trader", () => {
   });
 
   describe("trade", () => {
-    // it.only("basic check", async () => {
-    //   console.log(await ctx.DVM.methods.getPMMState().call())
-    //   console.log(await ctx.DVM.methods.getLpFeeRate(ctx.Deployer).call())
-    //   console.log(await ctx.DVM.methods.getMtFeeRate(ctx.Deployer).call())
-    //   console.log(await ctx.DVM.methods.querySellQuote(ctx.Deployer, decimalStr("200")).call())
-    // })
+    it.only("basic check", async () => {
+      console.log(await ctx.DVM.methods.getVaultReserve().call())
+      console.log(await ctx.DVM.methods.getPMMState().call())
+      console.log(await ctx.DVM.methods.getMidPrice().call())
+      console.log(await ctx.DVM.methods.querySellQuote(ctx.Deployer, decimalStr("200")).call())
+    })
+
     it("buy & sell", async () => {
 
       console.log("BASE0 before buy", await ctx.DVM.methods.getBase0().call())
@@ -123,7 +124,7 @@ describe("Trader", () => {
 
       // buy when quoet is not 0
       await logGas(ctx.DVMProxy.methods.sellQuoteOnDVM(ctx.DVM.options.address, trader, decimalStr("200"), decimalStr("1")), ctx.sendParam(trader), "buy base token")
-      assert.equal("BASE0 after second buy", await ctx.DVM.methods.getBase0().call())
+      console.log("BASE0 after second buy", await ctx.DVM.methods.getBase0().call())
       // trader balances
       assert.equal(
         await ctx.BASE.methods.balanceOf(trader).call(),
@@ -152,5 +153,15 @@ describe("Trader", () => {
         "103733009669408099"
       );
     });
+
+    it("flash loan", async () => {
+
+    })
+
+    it("revert cases", async () => {
+      await assert.fail(
+        ctx.DVMProxy.methods.sellQuoteOnDVM(ctx.DVM.options.address, trader, decimalStr("200"), decimalStr("1")).send({ from: trader, gas: 300000, gasPrice: gweiStr("200") }), /GAS_PRICE_EXCEED/
+      )
+    })
   });
-});
+});
\ No newline at end of file