diff --git a/packages/testcases/src.ts/index.ts b/packages/testcases/src.ts/index.ts
index dffac0b0a..2243a6e10 100644
--- a/packages/testcases/src.ts/index.ts
+++ b/packages/testcases/src.ts/index.ts
@@ -7,104 +7,8 @@ import zlib from 'browserify-zlib';
 import { randomBytes, randomHexString, randomNumber } from "./random";
 export { randomBytes, randomHexString, randomNumber };
 
-export module TestCase {
-    export type BigNumber = {
-        testcase: string;
-        value: string | number;
-        expectedValue: string;
-    };
-
-    export type Hash = {
-        data: string;
-        keccak256: string;
-        sha256: string;
-        sha512: string;
-    };
-
-    export type HDWalletNode = {
-        path: string;
-        address: string;
-        privateKey: string;
-    };
-
-    export type HDWallet = {
-        name: string;
-
-        seed: string;
-        locale: string;
-        password?: string;
-        entropy: string;
-        mnemonic: string;
-
-        hdnodes: Array<HDWalletNode>
-    };
-
-    export type Nameprep = {
-        comment: string;
-        input: Array<number>;
-        output: Array<number>;
-        rc?: string;
-        flags?: string;
-    };
-
-    export type Wallet = {
-        name: string;
-        type: "crowdsale" | "secret-storage";
-        hasAddress: boolean;
-        address: string;
-        privateKey: string;
-        mnemonic?: string;
-        password?: string;
-        json: string;
-    };
-
-    export type Wordlist = {
-        locale: string;
-        content: string;
-    };
-
-    export type Unit = {
-         name: string
-
-         ether: string,
-         ether_format: string,
-
-         wei: string,
-
-         kwei?: string,
-         mwei?: string,
-         gwei?: string,
-         szabo?: string,
-         finney?: string,
-         satoshi?: string
-
-         kwei_format?: string,
-         mwei_format?: string,
-         gwei_format?: string,
-         szabo_format?: string,
-         finney_format?: string,
-         satoshi_format?: string
-    }
-
-    export type SignedTransaction = {
-        name: string;
-        accountAddress: string;
-        privateKey: string;
-
-        signedTransaction: string
-        unsignedTransaction: string;
-
-        signedTransactionChainId5: string
-        unsignedTransactionChainId5: string;
-
-        nonce: number;
-        gasLimit: string;
-        gasPrice: string;
-        to: string;
-        value: string;
-        data: string;
-    };
-}
+import * as TestCase from "./testcases";
+export { TestCase };
 
 export function saveTests(tag: string, data: any) {
    //let filename = path.resolve(__dirname, 'testcases', tag + '.json.gz');
@@ -115,7 +19,7 @@ export function saveTests(tag: string, data: any) {
    console.log('Save testcase: ' + filename);
 }
 
-export function loadTests(tag: string): any {
+export function loadTests<T = any>(tag: string): T {
    let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
    return JSON.parse(zlib.gunzipSync(fs.readFileSync(filename)).toString());
 }
diff --git a/packages/testcases/src.ts/testcases.ts b/packages/testcases/src.ts/testcases.ts
new file mode 100644
index 000000000..4dfd78ef4
--- /dev/null
+++ b/packages/testcases/src.ts/testcases.ts
@@ -0,0 +1,130 @@
+
+/*
+export interface TestCase {
+    name: string;
+};
+*/
+
+export interface BigNumber {
+    testcase: string;
+    value: string | number;
+    expectedValue: string;
+};
+
+export interface Hash {
+    data: string;
+    keccak256: string;
+    sha256: string;
+    sha512: string;
+};
+
+export interface HDWalletNode {
+    path: string;
+    address: string;
+    privateKey: string;
+};
+
+export interface HDWallet {
+    name: string;
+
+    seed: string;
+    locale: string;
+    password?: string;
+    entropy: string;
+    mnemonic: string;
+
+    hdnodes: Array<HDWalletNode>
+};
+
+export interface Nameprep {
+    comment: string;
+    input: Array<number>;
+    output: Array<number>;
+    rc?: string;
+    flags?: string;
+};
+
+export interface Wallet {
+    name: string;
+
+    type: "crowdsale" | "secret-storage";
+    hasAddress: boolean;
+    address: string;
+    privateKey: string;
+    mnemonic?: string;
+    password?: string;
+    json: string;
+};
+
+export interface Wordlist {
+    locale: string;
+    content: string;
+};
+
+export interface Unit {
+    name: string;
+
+    ether: string,
+    ether_format: string,
+    wei: string,
+
+    kwei?: string,
+    mwei?: string,
+    gwei?: string,
+    szabo?: string,
+    finney?: string,
+    satoshi?: string
+
+    kwei_format?: string,
+    mwei_format?: string,
+    gwei_format?: string,
+    szabo_format?: string,
+    finney_format?: string,
+    satoshi_format?: string
+};
+
+export interface SignedTransaction {
+    name: string;
+
+    accountAddress: string;
+    privateKey: string;
+
+    signedTransaction: string
+    unsignedTransaction: string;
+
+    signedTransactionChainId5: string
+    unsignedTransactionChainId5: string;
+
+    nonce: number;
+    gasLimit: string;
+    gasPrice: string;
+    to: string;
+    value: string;
+    data: string;
+};
+
+export interface Eip712 {
+    name: string;
+
+    domain: {
+        name: string;
+        version?: string;
+        chainId?: number;
+        verifyingContract?: string;
+        salt?: string;
+    },
+    primaryType: string;
+    types: Record<string, Array<{ name: string, type: string }>>;
+    data: Record<string, any>;
+    encoded: string;
+    digest: string;
+
+    // Only random tests
+    type?: string;
+    seed?: string;
+
+    // Not all testcases have these
+    privateKey?: string;
+    signature?: string;
+};
+
diff --git a/packages/testcases/testcases/eip712.json.gz b/packages/testcases/testcases/eip712.json.gz
new file mode 100644
index 000000000..1e385a1b5
Binary files /dev/null and b/packages/testcases/testcases/eip712.json.gz differ
diff --git a/packages/tests/src.ts/test-utils.ts b/packages/tests/src.ts/test-utils.ts
index 2e77544af..469ac9fb2 100644
--- a/packages/tests/src.ts/test-utils.ts
+++ b/packages/tests/src.ts/test-utils.ts
@@ -732,17 +732,17 @@ describe("Logger", function() {
     });
 });
 
-/*
 describe("Base58 Coder", function() {
     it("decodes", function() {
-        assert.equal(ethers.utils.Base58.decode("JxF12TrwUP45BMd"), "Hello World");
+        assert.equal(ethers.utils.toUtf8String(ethers.utils.base58.decode("JxF12TrwUP45BMd")), "Hello World");
     });
 
     it("encodes", function() {
-        assert.equal(ethers.utils.Base58.encode("Hello World"), "JxF12TrwUP45BMd");
+        assert.equal(ethers.utils.base58.encode(ethers.utils.toUtf8Bytes("Hello World")), "JxF12TrwUP45BMd");
     });
 });
 
+/*
 describe("Web Fetch", function() {
     it("fetches JSON", async function() {
         const url = "https:/\/api.etherscan.io/api?module=stats&action=ethprice&apikey=9D13ZE7XSBTJ94N9BNJ2MA33VMAY2YPIRB";
@@ -750,3 +750,29 @@ describe("Web Fetch", function() {
     });
 });
 */
+
+describe("EIP-712", function() {
+    const tests = loadTests<Array<TestCase.Eip712>>("eip712");
+
+    tests.forEach((test) => {
+        it(`encoding ${ test.name }`, function() {
+            const encoder = ethers.utils._TypedDataEncoder.from(test.types);
+            assert.equal(encoder.primaryType, test.primaryType, "instance.primaryType");
+            assert.equal(encoder.encode(test.data), test.encoded, "instance.encode()");
+
+            //console.log(test);
+            assert.equal(ethers.utils._TypedDataEncoder.getPrimaryType(test.types), test.primaryType, "getPrimaryType");
+            assert.equal(ethers.utils._TypedDataEncoder.hash(test.domain, test.types, test.data), test.digest, "digest");
+        });
+    });
+
+    tests.forEach((test) => {
+        if (!test.privateKey) { return; }
+        it(`signing ${ test.name }`, async function() {
+            const wallet = new ethers.Wallet(test.privateKey);
+            const signature = await wallet._signTypedData(test.domain, test.types, test.data);
+            assert.equal(signature, test.signature, "signature");
+        });
+    });
+});
+