Merge pull request #172 from keep-network/improve-branch-tests

Improve Coverage and Instructiveness for branchTest.js

Author: lukasz-zimnoch

test/branchTest.js

@@ -2,6 +2,11 @@ const { BigNumber } = require("ethers")
 const { expect } = require("chai")
 
 describe("Branch", () => {
+  // A branch is a uint256, meaning it's represented with 256 bits. Each branch
+  // represents 8 children, where each child gets 32 sequential bits. A hex
+  // number represents 4 bits, so an 8-character long hex string is 32 bits. We
+  // store children right-to-left, and use values like 00000000 and 11111111 to
+  // make it visually clear where one slot starts and stops.
   const node = BigNumber.from(
     "0x7777777766666666555555554444444433333333222222221111111100000000",
   )
@@ -20,37 +25,94 @@ describe("Branch", () => {
 
   describe("getSlot", async () => {
     it("Returns the uint16 in the correct position", async () => {
-      const result = await branchInstance.getSlot(node, 3)
-      expect(result).to.be.equal(0x33333333)
+      const expectations = [
+        0x00000000, 0x11111111, 0x22222222, 0x33333333, 0x44444444, 0x55555555,
+        0x66666666, 0x77777777,
+      ]
+      for (let slot = 0; slot < 8; slot++) {
+        const result = await branchInstance.getSlot(node, slot)
+        expect(result).to.equal(
+          expectations[slot],
+          `unexpected result at position ${slot}`,
+        )
+      }
     })
   })
 
   describe("clearSlot", async () => {
     it("Clears the correct slot", async () => {
-      newNode =
-        "0x7777777766666666555555554444444400000000222222221111111100000000"
+      const expectations = [
+        "0x7777777766666666555555554444444433333333222222221111111100000000",
+        "0x7777777766666666555555554444444433333333222222220000000000000000",
+        "0x7777777766666666555555554444444433333333000000001111111100000000",
+        "0x7777777766666666555555554444444400000000222222221111111100000000",
+        "0x7777777766666666555555550000000033333333222222221111111100000000",
+        "0x7777777766666666000000004444444433333333222222221111111100000000",
+        "0x7777777700000000555555554444444433333333222222221111111100000000",
+        "0x66666666555555554444444433333333222222221111111100000000",
+      ]
 
-      const result = await branchInstance.clearSlot(node, 3)
-      expect(ethers.utils.hexlify(result)).to.be.equal(newNode)
+      for (let slot = 0; slot < 8; slot++) {
+        const result = await branchInstance.clearSlot(node, slot)
+        expect(ethers.utils.hexlify(result)).to.equal(
+          expectations[slot],
+          `unexpected result at position ${slot}`,
+        )
+      }
+
+      // verify that clearing slot 0 actually works!
+      const onesNode = BigNumber.from(
+        "0x1111111111111111111111111111111111111111111111111111111111111111",
+      )
+      const result = await branchInstance.clearSlot(onesNode, 0)
+      const expectation =
+        "0x1111111111111111111111111111111111111111111111111111111100000000"
+      expect(ethers.utils.hexlify(result)).to.equal(expectation)
     })
   })
 
   describe("setSlot", async () => {
     it("Changes the correct slot", async () => {
-      newNode =
-        "0x7777777766666666555555554444444412345678222222221111111100000000"
-      w = 0x12345678
+      const newWeight = 0x12345678
+      const expectations = [
+        "0x7777777766666666555555554444444433333333222222221111111112345678",
+        "0x7777777766666666555555554444444433333333222222221234567800000000",
+        "0x7777777766666666555555554444444433333333123456781111111100000000",
+        "0x7777777766666666555555554444444412345678222222221111111100000000",
+        "0x7777777766666666555555551234567833333333222222221111111100000000",
+        "0x7777777766666666123456784444444433333333222222221111111100000000",
+        "0x7777777712345678555555554444444433333333222222221111111100000000",
+        "0x1234567866666666555555554444444433333333222222221111111100000000",
+      ]
+      for (let slot = 0; slot < 8; slot++) {
+        const result = await branchInstance.setSlot(node, slot, newWeight)
+        expect(ethers.utils.hexlify(result)).to.equal(
+          expectations[slot],
+          `unexpected result at position ${slot}`,
+        )
 
-      const modified = await branchInstance.setSlot(node, 3, w)
-      newSlot = await branchInstance.getSlot(modified, 3)
-      expect(ethers.utils.hexlify(modified)).to.be.equal(newNode)
+        const newSlot = await branchInstance.getSlot(result, slot)
+        expect(newSlot).to.equal(
+          newWeight,
+          `unexpected result at position ${slot}`,
+        )
+      }
     })
   })
 
   describe("sumWeight", async () => {
     it("Returns the correct weight", async () => {
       const weight = await branchInstance.sumWeight(node)
-      const expected = 0x77777777 * 4
+      const expected =
+        0x00000000 +
+        0x11111111 +
+        0x22222222 +
+        0x33333333 +
+        0x44444444 +
+        0x55555555 +
+        0x66666666 +
+        0x77777777
+
       expect(weight).to.be.equal(expected)
     })
   })