feat(credentials): add the blockchain balance validator

libs/credentials/src/index.test.ts

@@ -28,15 +28,15 @@ describe("Credentials library", () => {
         it("Should add a validator to the list of supported validators", () => {
             addValidator({} as any)
 
-            expect(validators).toHaveLength(7)
+            expect(validators).toHaveLength(8)
         })
     })
 
     describe("# addValidators", () => {
         it("Should add 2 validators to the list of supported validators", () => {
             addValidators([{} as any, {} as any])
 
-            expect(validators).toHaveLength(9)
+            expect(validators).toHaveLength(10)
         })
     })
 

libs/credentials/src/validators.ts

@@ -5,7 +5,8 @@ import {
     githubRepositoryCommits,
     twitterFollowers,
     twitterFollowingUser,
-    blockchainTransactions
+    blockchainTransactions,
+    blockchainBalance
 } from "./validators/index"
 
 const validators: Validator[] = [
@@ -14,7 +15,8 @@ const validators: Validator[] = [
     githubRepositoryCommits,
     twitterFollowers,
     twitterFollowingUser,
-    blockchainTransactions
+    blockchainTransactions,
+    blockchainBalance
 ]
 
 export default validators

libs/credentials/src/validators/blockchainBalance/index.test.ts

@@ -0,0 +1,107 @@
+import { BigNumber } from "ethers"
+import { validateCredentials } from "../.."
+import blockchainBalance from "./index"
+
+describe("BlockchainBalance", () => {
+    const jsonRpcProviderMocked = {
+        getBalance: jest.fn()
+    }
+
+    it("Should return true if an account has a balance greater than or equal to 10", async () => {
+        jsonRpcProviderMocked.getBalance.mockReturnValue(BigNumber.from(12))
+
+        const result = await validateCredentials(
+            {
+                id: blockchainBalance.id,
+                criteria: {
+                    minBalance: "10"
+                }
+            },
+            {
+                address: "0x",
+                jsonRpcProvider: jsonRpcProviderMocked
+            }
+        )
+
+        expect(result).toBeTruthy()
+    })
+
+    it("Should return true if an account has a balance greater than or equal to 10 using the block number", async () => {
+        jsonRpcProviderMocked.getBalance.mockReturnValue(BigNumber.from(12))
+
+        const result = await validateCredentials(
+            {
+                id: blockchainBalance.id,
+                criteria: {
+                    minBalance: "10"
+                }
+            },
+            {
+                address: "0x",
+                jsonRpcProvider: jsonRpcProviderMocked,
+                blockNumber: 4749638
+            }
+        )
+
+        expect(result).toBeTruthy()
+    })
+
+    it("Should throw an error if a criteria parameter is missing", async () => {
+        const fun = () =>
+            validateCredentials(
+                {
+                    id: blockchainBalance.id,
+                    criteria: {}
+                },
+                {
+                    address: "0x",
+                    jsonRpcProvider: undefined
+                }
+            )
+
+        await expect(fun).rejects.toThrow(
+            "Parameter 'minBalance' has not been defined"
+        )
+    })
+
+    it("Should throw an error if a criteria parameter should not exist", async () => {
+        const fun = () =>
+            validateCredentials(
+                {
+                    id: blockchainBalance.id,
+                    criteria: {
+                        minBalance: "100",
+                        minStars: 200
+                    }
+                },
+                {
+                    address: "0x",
+                    jsonRpcProvider: undefined
+                }
+            )
+
+        await expect(fun).rejects.toThrow(
+            "Parameter 'minStars' should not be part of the criteria"
+        )
+    })
+
+    it("Should throw a type error if a criteria parameter has the wrong type", async () => {
+        const fun = () =>
+            validateCredentials(
+                {
+                    id: blockchainBalance.id,
+                    criteria: {
+                        minBalance: 100
+                    }
+                },
+                {
+                    address: "0x",
+                    jsonRpcProvider: undefined
+                }
+            )
+
+        await expect(fun).rejects.toThrow(
+            "Parameter 'minBalance' is not a string"
+        )
+    })
+})

libs/credentials/src/validators/blockchainBalance/index.ts

@@ -0,0 +1,35 @@
+import { BigNumber } from "ethers"
+import { BlockchainContext, Validator } from "../.."
+
+export type Criteria = {
+    minBalance: string
+}
+
+const validator: Validator = {
+    id: "BLOCKCHAIN_BALANCE",
+
+    criteriaABI: {
+        minBalance: "string"
+    },
+
+    /**
+     * It checks if a user has a balance greater than or equal to 'minBalance'.
+     * @param criteria The criteria used to check user's credentials.
+     * @param context Context variables.
+     * @returns True if the user meets the criteria.
+     */
+    async validate(criteria: Criteria, context) {
+        if ("address" in context) {
+            const balance = await (
+                context as BlockchainContext
+            ).jsonRpcProvider.getBalance(
+                (context as BlockchainContext).address,
+                (context as BlockchainContext).blockNumber
+            )
+            return balance >= BigNumber.from(criteria.minBalance)
+        }
+        throw new Error("No address value found")
+    }
+}
+
+export default validator

libs/credentials/src/validators/index.ts

@@ -4,12 +4,14 @@ import githubRepositoryCommits from "./githubRepositoryCommits"
 import twitterFollowers from "./twitterFollowers"
 import twitterFollowingUser from "./twitterFollowingUser"
 import blockchainTransactions from "./blockchainTransactions"
+import blockchainBalance from "./blockchainBalance"
 
 export {
     githubFollowers,
     githubRepositoryCommits,
     twitterFollowers,
     twitterFollowingUser,
     githubPersonalStars,
-    blockchainTransactions
+    blockchainTransactions,
+    blockchainBalance
 }