Cheaper Gas v2

contracts/FundMe.sol

@@ -41,12 +41,12 @@ contract FundMe {
     /***** 6.1 Type Declarations *****/
     using PriceConverter for uint256;
     uint256 public constant MINIMUM_USD = 50 * 1e18;
-    address[] public s_funders;
-    address public immutable i_owner; // immutable only can declare 1 time at contructor
-    AggregatorV3Interface public s_priceFeed;
+    address[] private s_funders;
+    address private immutable i_owner; // immutable only can declare 1 time at contructor
+    AggregatorV3Interface private s_priceFeed;
 
     /***** 6.2 State Variable *****/
-    mapping(address => uint256) public s_addressToAmountFunded;
+    mapping(address => uint256) private s_addressToAmountFunded;
 
     /***** 6.3 Modifier *****/
     modifier onlyOwner() {
@@ -94,7 +94,7 @@ contract FundMe {
         require(
             msg.value.getConversionRate(s_priceFeed) >= MINIMUM_USD,
             "Didn't send enough"
-        );
+        ); // Use error code is gas cheaper
         s_funders.push(msg.sender);
         s_addressToAmountFunded[msg.sender] = msg.value;
     }
@@ -147,4 +147,23 @@ contract FundMe {
         (bool callSuccess, ) = i_owner.call{value: address(this).balance}("");
         require(callSuccess, "Call failed");
     }
+
+    // private variable is gas cheaper
+    function getOwner() public view returns (address) {
+        return i_owner;
+    }
+
+    function getFunders(uint256 index) public view returns (address) {
+        return s_funders[index];
+    }
+
+    function getAddressToAmountFunded(
+        address funder
+    ) public view returns (uint256) {
+        return s_addressToAmountFunded[funder];
+    }
+
+    function getPriceFeed() public view returns (AggregatorV3Interface) {
+        return s_priceFeed;
+    }
 }

test/unit/FundMeTest.js

@@ -25,18 +25,18 @@ describe("FundMe", function () {
     eth1 = ethers.utils.parseEther("1"); // Same 1 ETH
     describe("constructor", async function () {
         it("Set the aggregator priceFeedAddress correctly", async function () {
-            const response = await fundMe.s_priceFeed(); // AggregatorV3Interface
+            const response = await fundMe.getPriceFeed(); // AggregatorV3Interface
             //console.log("AggregatorV3Interface" + response);
             assert.equal(response, mockV3Aggregator.address);
         });
         it("Updated the amount funded data structure", async function () {
             await fundMe.fund({ value: eth1 });
-            const response = await fundMe.s_addressToAmountFunded(deployer);
+            const response = await fundMe.getAddressToAmountFunded(deployer);
             assert.equal(response.toString(), eth1.toString()); // Send 1 ETH
         });
         it("Adds funder to array of funders", async function () {
             await fundMe.fund({ value: eth1 });
-            const funder = await fundMe.s_funders(0);
+            const funder = await fundMe.getFunders(0);
             assert.equal(funder, deployer);
         });
     });
@@ -80,10 +80,10 @@ describe("FundMe", function () {
             });
 
             // Check if addr1 is added to funders
-            expect(await fundMe.s_funders(0)).to.equal(addr1.address);
+            expect(await fundMe.getFunders(0)).to.equal(addr1.address);
             // Check if the amount funded is recorded
             expect(
-                await fundMe.s_addressToAmountFunded(addr1.address),
+                await fundMe.getAddressToAmountFunded(addr1.address),
             ).to.equal(ethers.utils.parseEther("1.0"));
         });
 
@@ -110,9 +110,9 @@ describe("FundMe", function () {
                 }),
             ).not.to.be.reverted;
 
-            expect(await fundMe.s_funders(0)).to.equal(addr1.address);
+            expect(await fundMe.getFunders(0)).to.equal(addr1.address);
             expect(
-                await fundMe.s_addressToAmountFunded(addr1.address),
+                await fundMe.getAddressToAmountFunded(addr1.address),
             ).to.equal(minFunding);
         });
     });
@@ -191,11 +191,11 @@ describe("FundMe", function () {
                 endingDeployerBalance.add(withdrawGasCost).toString(),
             );
             // Make a getter for storage variables
-            await expect(fundMe.s_funders(0)).to.be.reverted;
+            await expect(fundMe.getFunders(0)).to.be.reverted;
 
             for (i = 1; i < 6; i++) {
                 assert.equal(
-                    await fundMe.s_addressToAmountFunded(accounts[i].address),
+                    await fundMe.getAddressToAmountFunded(accounts[i].address),
                     0,
                 );
             }
@@ -286,11 +286,11 @@ describe("FundMe", function () {
                 endingDeployerBalance.add(withdrawGasCost).toString(),
             );
             // Make a getter for storage variables
-            await expect(fundMe.s_funders(0)).to.be.reverted;
+            await expect(fundMe.getFunders(0)).to.be.reverted;
 
             for (i = 1; i < 6; i++) {
                 assert.equal(
-                    await fundMe.s_addressToAmountFunded(accounts[i].address),
+                    await fundMe.getAddressToAmountFunded(accounts[i].address),
                     0,
                 );
             }