Change the test to verify the actual gas used instead of the buggy estimated gas used

package.json

@@ -23,6 +23,7 @@
   },
   "scripts": {
     "lint": "yarn prettier ./test/*.ts --check",
+    "lint:fix": "yarn prettier ./test/*.ts --write",
     "clean": "rimraf ./build/",
     "precompile": "yarn clean",
     "compile": "waffle .waffle.json",

test/UniswapV2Factory.spec.ts

@@ -66,8 +66,9 @@ describe('UniswapV2Factory', () => {
   })
 
   it('createPair:gas', async () => {
-    const gasCost = await factory.estimate.createPair(...TEST_ADDRESSES)
-    expect(gasCost).to.eq(2512920)
+    const tx = await factory.createPair(...TEST_ADDRESSES)
+    const receipt = await tx.wait()
+    expect(receipt.gasUsed).to.eq(2512920)
   })
 
   it('setFeeTo', async () => {

test/UniswapV2Pair.spec.ts

@@ -176,8 +176,9 @@ describe('UniswapV2Pair', () => {
     const expectedOutputAmount = bigNumberify('453305446940074565')
     await token1.transfer(pair.address, swapAmount)
     await mineBlock(provider, (await provider.getBlock('latest')).timestamp + 1)
-    const gasCost = await pair.estimate.swap(expectedOutputAmount, 0, wallet.address, '0x', overrides)
-    expect(gasCost).to.eq(79136)
+    const tx = await pair.swap(expectedOutputAmount, 0, wallet.address, '0x', overrides)
+    const receipt = await tx.wait()
+    expect(receipt.gasUsed).to.eq(73462)
   })
 
   it('burn', async () => {