Uint and Time helpers

contracts/common/Initializable.sol

@@ -40,4 +40,31 @@ contract Initializable is AppStorage {
     function getBlockNumber() internal view returns (uint256) {
         return block.number;
     }
+
+    /**
+    * @dev Returns the current block number, converted to uint64.
+    *      Using a function rather than `block.number` allows us to easily mock the block number in
+    *      tests.
+    */
+    function getBlockNumber64() internal view returns (uint64) {
+        return uint64(block.number);
+    }
+
+    /**
+    * @dev Returns the current timestamp.
+    *      Using a function rather than `now` allows us to easily mock it in
+    *      tests.
+    */
+    function getTimestamp() internal view returns (uint256) {
+        return now;
+    }
+
+    /**
+    * @dev Returns the current timestamp, covnerted to uint64.
+    *      Using a function rather than `now` allows us to easily mock it in
+    *      tests.
+    */
+    function getTimestamp64() internal view returns (uint64) {
+        return uint64(now);
+    }
 }

contracts/lib/misc/Uint64Helpers.sol

@@ -0,0 +1,11 @@
+pragma solidity ^0.4.18;
+
+
+library Uint64Helpers {
+    uint256 public constant MAX_UINT64 = uint64(-1);
+
+    function toUint64(uint256 a) internal pure returns (uint64) {
+        require(a <= MAX_UINT64);
+        return uint64(a);
+    }
+}

test/lib_uint64_helpers.js

@@ -0,0 +1,21 @@
+const { assertRevert } = require('./helpers/assertThrow')
+
+contract('Uint64 Helpers test', accounts => {
+  let uint64Mock
+
+  before(async () => {
+    uint64Mock = await artifacts.require('Uint64Mock').new()
+  })
+
+  it('converts from uint256 to uint64', async () => {
+    const a = 1234
+    assert.equal((await uint64Mock.convert.call(a)).toString(), a, "Values should match")
+  })
+
+  it('fails converting from uint256 to uint64 if too big', async () => {
+    const a = new web3.BigNumber(2).pow(64)
+    return assertRevert(async () => {
+      assert.equal((await uint64Mock.convert(a)).toString(), a, "Values should match")
+    })
+  })
+})

test/mocks/Uint64Mock.sol

@@ -0,0 +1,12 @@
+pragma solidity 0.4.18;
+
+import "../../contracts/lib/misc/Uint64Helpers.sol";
+
+
+contract Uint64Mock {
+    using Uint64Helpers for uint256;
+
+    function convert(uint256 a) public pure returns (uint64) {
+        return a.toUint64();
+    }
+}