Merge branch 'v2-prototype' into refactor/check-revert-reasons

* v2-prototype: (48 commits)
  Fix typos in comments
  Add modifier and tests for removeAuthorizedAddressAtIndex
  Update and add tests
  Change removeAuthorizedAddress => removeAuthorizedAddressAtIndex
  Move isFunctionRemoveAuthorizedAddress to test
  Fix usage of `popLastByte`
  Fix LibBytes is a library
  Remove `areBytesEqual`
  Fix usage of `contentAddress()`
  Clean low bits in bytes4
  Clean high bits in address
  Refactor LibBytes.readBytes4 for consistency
  Fix LibBytes.equals
  Add trailing garbage testcase for LibBytes.equals
  Rename bytes.equals
  Add slice and sliceDestructive
  Rename bytes.rawAddress and add bytes.contentAddress
  Rename read/writeBytesWithLength
  Using LibBytes for bytes
  Make LibBytes a library
  ...

# Conflicts:
#	packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol
#	packages/contracts/test/libraries/lib_bytes.ts

1 files changed, 256 insertions, 45 deletions

diff --git a/packages/contracts/test/libraries/lib_bytes.ts b/packages/contracts/test/libraries/lib_bytes.ts
index 7db0f60b5..e4b3abb7f 100644
--- a/packages/contracts/test/libraries/lib_bytes.ts
+++ b/packages/contracts/test/libraries/lib_bytes.ts
@@ -18,6 +18,12 @@ chaiSetup.configure();
 const expect = chai.expect;
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 
+// BUG: Ideally we would use Buffer.from(memory).toString('hex')
+// https://github.com/Microsoft/TypeScript/issues/23155
+const toHex = (buf: Uint8Array): string => buf.reduce((a, v) => a + ('00' + v.toString(16)).slice(-2), '0x');
+
+const fromHex = (str: string): Uint8Array => Uint8Array.from(Buffer.from(str.slice(2), 'hex'));
+
 describe('LibBytes', () => {
     let libBytes: TestLibBytesContract;
     const byteArrayShorterThan32Bytes = '0x012345';
@@ -124,48 +130,55 @@ describe('LibBytes', () => {
         });
     });
 
-    describe('areBytesEqual', () => {
+    describe('equals', () => {
         it('should return true if byte arrays are equal (both arrays < 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayShorterThan32Bytes,
                 byteArrayShorterThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.true();
+            return expect(isEqual).to.be.true();
         });
         it('should return true if byte arrays are equal (both arrays > 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32Bytes,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.true();
+            return expect(isEqual).to.be.true();
         });
         it('should return false if byte arrays are not equal (first array < 32 bytes, second array > 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayShorterThan32Bytes,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
         });
         it('should return false if byte arrays are not equal (first array > 32 bytes, second array < 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32Bytes,
                 byteArrayShorterThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
         });
         it('should return false if byte arrays are not equal (same length, but a byte in first word differs)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32BytesFirstBytesSwapped,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
         });
         it('should return false if byte arrays are not equal (same length, but a byte in last word differs)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32BytesLastBytesSwapped,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
+        });
+
+        describe('should ignore trailing data', () => {
+            it('should return true when both < 32 bytes', async () => {
+                const isEqual = await libBytes.publicEqualsPop1.callAsync('0x0102', '0x0103');
+                return expect(isEqual).to.be.true();
+            });
         });
     });
 
@@ -444,26 +457,26 @@ describe('LibBytes', () => {
         });
     });
 
-    describe('readFirst4', () => {
+    describe('readBytes4', () => {
         // AssertionError: expected promise to be rejected with an error including 'revert' but it was fulfilled with '0x08c379a0'
         it('should revert if byte array has a length < 4', async () => {
             const byteArrayLessThan4Bytes = '0x010101';
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadFirst4.callAsync(byteArrayLessThan4Bytes),
+                libBytes.publicReadBytes4.callAsync(byteArrayLessThan4Bytes, new BigNumber(0)),
                 RevertReasons.LibBytesGreaterOrEqualTo4LengthRequired,
             );
         });
         it('should return the first 4 bytes of a byte array of arbitrary length', async () => {
-            const first4Bytes = await libBytes.publicReadFirst4.callAsync(byteArrayLongerThan32Bytes);
+            const first4Bytes = await libBytes.publicReadBytes4.callAsync(byteArrayLongerThan32Bytes, new BigNumber(0));
             const expectedFirst4Bytes = byteArrayLongerThan32Bytes.slice(0, 10);
             expect(first4Bytes).to.equal(expectedFirst4Bytes);
         });
     });
 
-    describe('readBytes', () => {
+    describe('readBytesWithLength', () => {
         it('should successfully read short, nested array of bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
-            const bytes = await libBytes.publicReadBytes.callAsync(shortTestBytes, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(shortTestBytes, testBytesOffset);
             return expect(bytes).to.be.equal(shortData);
         });
         it('should successfully read short, nested array of bytes when it is offset in the array', async () => {
@@ -471,12 +484,12 @@ describe('LibBytes', () => {
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, shortTestBytesAsBuffer]);
             const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
             const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
-            const bytes = await libBytes.publicReadBytes.callAsync(combinedByteArray, testUint256Offset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
             return expect(bytes).to.be.equal(shortData);
         });
         it('should successfully read a nested array of bytes - one word in length - when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
-            const bytes = await libBytes.publicReadBytes.callAsync(wordOfTestBytes, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(wordOfTestBytes, testBytesOffset);
             return expect(bytes).to.be.equal(wordOfData);
         });
         it('should successfully read a nested array of bytes - one word in length - when it is offset in the array', async () => {
@@ -484,12 +497,12 @@ describe('LibBytes', () => {
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, wordOfTestBytesAsBuffer]);
             const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
             const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
-            const bytes = await libBytes.publicReadBytes.callAsync(combinedByteArray, testUint256Offset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
             return expect(bytes).to.be.equal(wordOfData);
         });
         it('should successfully read long, nested array of bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
-            const bytes = await libBytes.publicReadBytes.callAsync(longTestBytes, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(longTestBytes, testBytesOffset);
             return expect(bytes).to.be.equal(longData);
         });
         it('should successfully read long, nested array of bytes when it is offset in the array', async () => {
@@ -497,46 +510,50 @@ describe('LibBytes', () => {
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, longTestBytesAsBuffer]);
             const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
             const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
-            const bytes = await libBytes.publicReadBytes.callAsync(combinedByteArray, testUint256Offset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
             return expect(bytes).to.be.equal(longData);
         });
         it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
             // The length of the nested array is 32 bytes. By storing less than 32 bytes, a length cannot be read.
             const offset = new BigNumber(0);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(byteArrayShorterThan32Bytes, offset),
+                libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, offset),
                 RevertReasons.LibBytesGreaterOrEqualTo32LengthRequired,
             );
         });
         it('should fail if we store a nested byte array length, without a nested byte array', async () => {
             const offset = new BigNumber(0);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(testBytes32, offset),
+                libBytes.publicReadBytesWithLength.callAsync(testBytes32, offset),
                 RevertReasons.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArrayShorterThan32Bytes).byteLength);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(byteArrayShorterThan32Bytes, badOffset),
+                libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, badOffset),
                 RevertReasons.LibBytesGreaterOrEqualTo32LengthRequired,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold the nested byte array', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(testBytes32).byteLength);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(testBytes32, badOffset),
+                libBytes.publicReadBytesWithLength.callAsync(testBytes32, badOffset),
                 RevertReasons.LibBytesGreaterOrEqualTo32LengthRequired,
             );
         });
     });
 
-    describe('writeBytes', () => {
+    describe('writeBytesWithLength', () => {
         it('should successfully write short, nested array of bytes when it takes up the whole array)', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
-            const bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, testBytesOffset, shortData);
-            const bytesRead = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                shortData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytesRead).to.be.equal(shortData);
         });
         it('should successfully write short, nested array of bytes when it is offset in the array', async () => {
@@ -547,19 +564,31 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(
                 new Buffer(prefixDataAsBuffer.byteLength + shortTestBytesAsBuffer.byteLength),
             );
-            let bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, prefixOffset, prefixData);
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
             // Write data after prefix
             const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
-            bytesWritten = await libBytes.publicWriteBytes.callAsync(bytesWritten, testBytesOffset, shortData);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                bytesWritten,
+                testBytesOffset,
+                shortData,
+            );
             // Read data after prefix and validate
-            const bytes = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytes).to.be.equal(shortData);
         });
         it('should successfully write a nested array of bytes - one word in length - when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(wordOfTestBytesAsBuffer.byteLength));
-            const bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, testBytesOffset, wordOfData);
-            const bytesRead = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                wordOfData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytesRead).to.be.equal(wordOfData);
         });
         it('should successfully write a nested array of bytes - one word in length - when it is offset in the array', async () => {
@@ -570,19 +599,31 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(
                 new Buffer(prefixDataAsBuffer.byteLength + wordOfTestBytesAsBuffer.byteLength),
             );
-            let bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, prefixOffset, prefixData);
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
             // Write data after prefix
             const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
-            bytesWritten = await libBytes.publicWriteBytes.callAsync(bytesWritten, testBytesOffset, wordOfData);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                bytesWritten,
+                testBytesOffset,
+                wordOfData,
+            );
             // Read data after prefix and validate
-            const bytes = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytes).to.be.equal(wordOfData);
         });
         it('should successfully write a long, nested bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(longTestBytesAsBuffer.byteLength));
-            const bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, testBytesOffset, longData);
-            const bytesRead = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                longData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytesRead).to.be.equal(longData);
         });
         it('should successfully write long, nested array of bytes when it is offset in the array', async () => {
@@ -593,19 +634,23 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(
                 new Buffer(prefixDataAsBuffer.byteLength + longTestBytesAsBuffer.byteLength),
             );
-            let bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, prefixOffset, prefixData);
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
             // Write data after prefix
             const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
-            bytesWritten = await libBytes.publicWriteBytes.callAsync(bytesWritten, testBytesOffset, longData);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(bytesWritten, testBytesOffset, longData);
             // Read data after prefix and validate
-            const bytes = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytes).to.be.equal(longData);
         });
         it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
             const offset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(1));
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicWriteBytes.callAsync(emptyByteArray, offset, longData),
+                libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, offset, longData),
                 RevertReasons.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
             );
         });
@@ -613,10 +658,176 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
             const badOffset = new BigNumber(ethUtil.toBuffer(shortTestBytesAsBuffer).byteLength);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicWriteBytes.callAsync(emptyByteArray, badOffset, shortData),
+                libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, badOffset, shortData),
                 RevertReasons.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
             );
         });
     });
+
+    describe('memCopy', () => {
+        // Create memory 0x000102...FF
+        const memSize = 256;
+        // tslint:disable:no-shadowed-variable
+        const memory = new Uint8Array(memSize).map((_, i) => i);
+        const memHex = toHex(memory);
+
+        // Reference implementation to test against
+        const refMemcpy = (mem: Uint8Array, dest: number, source: number, length: number): Uint8Array =>
+            Uint8Array.from(mem).copyWithin(dest, source, source + length);
+
+        // Test vectors: destination, source, length, job description
+        type Tests = Array<[number, number, number, string]>;
+
+        const test = (tests: Tests) =>
+            tests.forEach(([dest, source, length, job]) =>
+                it(job, async () => {
+                    const expected = refMemcpy(memory, dest, source, length);
+                    const resultStr = await libBytes.testMemcpy.callAsync(
+                        memHex,
+                        new BigNumber(dest),
+                        new BigNumber(source),
+                        new BigNumber(length),
+                    );
+                    const result = fromHex(resultStr);
+                    expect(result).to.deep.equal(expected);
+                }),
+            );
+
+        test([[0, 0, 0, 'copies zero bytes with overlap']]);
+
+        describe('copies forward', () =>
+            test([
+                [128, 0, 0, 'zero bytes'],
+                [128, 0, 1, 'one byte'],
+                [128, 0, 11, 'eleven bytes'],
+                [128, 0, 31, 'thirty-one bytes'],
+                [128, 0, 32, 'one word'],
+                [128, 0, 64, 'two words'],
+                [128, 0, 96, 'three words'],
+                [128, 0, 33, 'one word and one byte'],
+                [128, 0, 72, 'two words and eight bytes'],
+                [128, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word', () =>
+            test([
+                [16, 0, 0, 'zero bytes'],
+                [16, 0, 1, 'one byte'],
+                [16, 0, 11, 'eleven bytes'],
+                [16, 0, 16, 'sixteen bytes'],
+            ]));
+
+        describe('copies forward with one byte overlap', () =>
+            test([
+                [0, 0, 1, 'one byte'],
+                [10, 0, 11, 'eleven bytes'],
+                [30, 0, 31, 'thirty-one bytes'],
+                [31, 0, 32, 'one word'],
+                [32, 0, 33, 'one word and one byte'],
+                [71, 0, 72, 'two words and eight bytes'],
+                [99, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with thirty-one bytes overlap', () =>
+            test([
+                [0, 0, 31, 'thirty-one bytes'],
+                [1, 0, 32, 'one word'],
+                [2, 0, 33, 'one word and one byte'],
+                [41, 0, 72, 'two words and eight bytes'],
+                [69, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with one word overlap', () =>
+            test([
+                [0, 0, 32, 'one word'],
+                [1, 0, 33, 'one word and one byte'],
+                [41, 0, 72, 'two words and eight bytes'],
+                [69, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with one word and one byte overlap', () =>
+            test([
+                [0, 0, 33, 'one word and one byte'],
+                [40, 0, 72, 'two words and eight bytes'],
+                [68, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with two words overlap', () =>
+            test([
+                [0, 0, 64, 'two words'],
+                [8, 0, 72, 'two words and eight bytes'],
+                [36, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word and one byte overlap', () =>
+            test([[0, 0, 1, 'one byte'], [10, 0, 11, 'eleven bytes'], [15, 0, 16, 'sixteen bytes']]));
+
+        describe('copies backward', () =>
+            test([
+                [0, 128, 0, 'zero bytes'],
+                [0, 128, 1, 'one byte'],
+                [0, 128, 11, 'eleven bytes'],
+                [0, 128, 31, 'thirty-one bytes'],
+                [0, 128, 32, 'one word'],
+                [0, 128, 64, 'two words'],
+                [0, 128, 96, 'three words'],
+                [0, 128, 33, 'one word and one byte'],
+                [0, 128, 72, 'two words and eight bytes'],
+                [0, 128, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward within one word', () =>
+            test([
+                [0, 16, 0, 'zero bytes'],
+                [0, 16, 1, 'one byte'],
+                [0, 16, 11, 'eleven bytes'],
+                [0, 16, 16, 'sixteen bytes'],
+            ]));
+
+        describe('copies backward with one byte overlap', () =>
+            test([
+                [0, 0, 1, 'one byte'],
+                [0, 10, 11, 'eleven bytes'],
+                [0, 30, 31, 'thirty-one bytes'],
+                [0, 31, 32, 'one word'],
+                [0, 32, 33, 'one word and one byte'],
+                [0, 71, 72, 'two words and eight bytes'],
+                [0, 99, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with thirty-one bytes overlap', () =>
+            test([
+                [0, 0, 31, 'thirty-one bytes'],
+                [0, 1, 32, 'one word'],
+                [0, 2, 33, 'one word and one byte'],
+                [0, 41, 72, 'two words and eight bytes'],
+                [0, 69, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with one word overlap', () =>
+            test([
+                [0, 0, 32, 'one word'],
+                [0, 1, 33, 'one word and one byte'],
+                [0, 41, 72, 'two words and eight bytes'],
+                [0, 69, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with one word and one byte overlap', () =>
+            test([
+                [0, 0, 33, 'one word and one byte'],
+                [0, 40, 72, 'two words and eight bytes'],
+                [0, 68, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with two words overlap', () =>
+            test([
+                [0, 0, 64, 'two words'],
+                [0, 8, 72, 'two words and eight bytes'],
+                [0, 36, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word and one byte overlap', () =>
+            test([[0, 0, 1, 'one byte'], [0, 10, 11, 'eleven bytes'], [0, 15, 16, 'sixteen bytes']]));
+    });
 });
 // tslint:disable:max-file-line-count