Reorganize the repo structure (#2503)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

test/token/ERC20/utils/SafeERC20.test.js

@@ -0,0 +1,135 @@
+const { expectRevert } = require('@openzeppelin/test-helpers');
+
+const ERC20ReturnFalseMock = artifacts.require('ERC20ReturnFalseMock');
+const ERC20ReturnTrueMock = artifacts.require('ERC20ReturnTrueMock');
+const ERC20NoReturnMock = artifacts.require('ERC20NoReturnMock');
+const SafeERC20Wrapper = artifacts.require('SafeERC20Wrapper');
+
+contract('SafeERC20', function (accounts) {
+  const [ hasNoCode ] = accounts;
+
+  describe('with address that has no contract code', function () {
+    beforeEach(async function () {
+      this.wrapper = await SafeERC20Wrapper.new(hasNoCode);
+    });
+
+    shouldRevertOnAllCalls('Address: call to non-contract');
+  });
+
+  describe('with token that returns false on all calls', function () {
+    beforeEach(async function () {
+      this.wrapper = await SafeERC20Wrapper.new((await ERC20ReturnFalseMock.new()).address);
+    });
+
+    shouldRevertOnAllCalls('SafeERC20: ERC20 operation did not succeed');
+  });
+
+  describe('with token that returns true on all calls', function () {
+    beforeEach(async function () {
+      this.wrapper = await SafeERC20Wrapper.new((await ERC20ReturnTrueMock.new()).address);
+    });
+
+    shouldOnlyRevertOnErrors();
+  });
+
+  describe('with token that returns no boolean values', function () {
+    beforeEach(async function () {
+      this.wrapper = await SafeERC20Wrapper.new((await ERC20NoReturnMock.new()).address);
+    });
+
+    shouldOnlyRevertOnErrors();
+  });
+});
+
+function shouldRevertOnAllCalls (reason) {
+  it('reverts on transfer', async function () {
+    await expectRevert(this.wrapper.transfer(), reason);
+  });
+
+  it('reverts on transferFrom', async function () {
+    await expectRevert(this.wrapper.transferFrom(), reason);
+  });
+
+  it('reverts on approve', async function () {
+    await expectRevert(this.wrapper.approve(0), reason);
+  });
+
+  it('reverts on increaseAllowance', async function () {
+    // [TODO] make sure it's reverting for the right reason
+    await expectRevert.unspecified(this.wrapper.increaseAllowance(0));
+  });
+
+  it('reverts on decreaseAllowance', async function () {
+    // [TODO] make sure it's reverting for the right reason
+    await expectRevert.unspecified(this.wrapper.decreaseAllowance(0));
+  });
+}
+
+function shouldOnlyRevertOnErrors () {
+  it('doesn\'t revert on transfer', async function () {
+    await this.wrapper.transfer();
+  });
+
+  it('doesn\'t revert on transferFrom', async function () {
+    await this.wrapper.transferFrom();
+  });
+
+  describe('approvals', function () {
+    context('with zero allowance', function () {
+      beforeEach(async function () {
+        await this.wrapper.setAllowance(0);
+      });
+
+      it('doesn\'t revert when approving a non-zero allowance', async function () {
+        await this.wrapper.approve(100);
+      });
+
+      it('doesn\'t revert when approving a zero allowance', async function () {
+        await this.wrapper.approve(0);
+      });
+
+      it('doesn\'t revert when increasing the allowance', async function () {
+        await this.wrapper.increaseAllowance(10);
+      });
+
+      it('reverts when decreasing the allowance', async function () {
+        await expectRevert(
+          this.wrapper.decreaseAllowance(10),
+          'SafeERC20: decreased allowance below zero',
+        );
+      });
+    });
+
+    context('with non-zero allowance', function () {
+      beforeEach(async function () {
+        await this.wrapper.setAllowance(100);
+      });
+
+      it('reverts when approving a non-zero allowance', async function () {
+        await expectRevert(
+          this.wrapper.approve(20),
+          'SafeERC20: approve from non-zero to non-zero allowance',
+        );
+      });
+
+      it('doesn\'t revert when approving a zero allowance', async function () {
+        await this.wrapper.approve(0);
+      });
+
+      it('doesn\'t revert when increasing the allowance', async function () {
+        await this.wrapper.increaseAllowance(10);
+      });
+
+      it('doesn\'t revert when decreasing the allowance to a positive value', async function () {
+        await this.wrapper.decreaseAllowance(50);
+      });
+
+      it('reverts when decreasing the allowance to a negative value', async function () {
+        await expectRevert(
+          this.wrapper.decreaseAllowance(200),
+          'SafeERC20: decreased allowance below zero',
+        );
+      });
+    });
+  });
+}