Merge branch 'master' into solc-0.7

.mocharc.js

@@ -0,0 +1,3 @@
+module.exports = {
+  timeout: 4000,
+};

.solhint.json

@@ -5,6 +5,7 @@
     "mark-callable-contracts": "off",
     "no-empty-blocks": "off",
     "compiler-version": ["error", "^0.7.0"],
-    "private-vars-leading-underscore": "error"
+    "private-vars-leading-underscore": "error",
+    "reason-string": "off"
   }
 }

CODE_STYLE.md

@@ -1,69 +0,0 @@
-# Code Style
-
-We value clean code and consistency, and those are prerequisites for us to
-include new code in the repository. Before proposing a change, please read this
-document and take some time to familiarize yourself with the style of the
-existing codebase.
-
-## Solidity code
-
-In order to be consistent with all the other Solidity projects, we follow the
-[official recommendations documented in the Solidity style guide](http://solidity.readthedocs.io/en/latest/style-guide.html).
-
-Any exception or additions specific to our project are documented below.
-
-### Naming
-
-* Try to avoid acronyms and abbreviations.
-
-* All state variables should be private.
-
-* Private state variables should have an underscore prefix.
-
-    ```
-    contract TestContract {
-      uint256 private _privateVar;
-      uint256 internal _internalVar;
-    }
-    ```
-
-* Parameters must not be prefixed with an underscore.
-
-    ```
-    function test(uint256 testParameter1, uint256 testParameter2) {
-    ...
-    }
-    ```
-
-* Internal and private functions should have an underscore prefix.
-
-    ```
-    function _testInternal() internal {
-      ...
-    }
-    ```
-
-    ```
-    function _testPrivate() private {
-      ...
-    }
-    ```
-
-* Events should be emitted immediately after the state change that they
-  represent, and consequently they should be named in past tense.
-
-    ```
-    function _burn(address _who, uint256 _value) internal {
-      super._burn(_who, _value);
-      emit TokensBurned(_who, _value);
-    }
-    ```
-
-  Some standards (e.g. ERC20) use present tense, and in those cases the
-  standard specification prevails.
-  
-* Interface names should have a capital I prefix.
-
-    ```
-    interface IERC777 {
-    ```

GUIDELINES.md

@@ -28,37 +28,78 @@ Consistency on the way classes are used is paramount to an easier understanding
 #### D6 - Regular Audits
 Following good programming practices is a way to reduce the risk of vulnerabilities, but professional code audits are still needed. We will perform regular code audits on major releases, and hire security professionals to provide independent review.
 
-## Style Guidelines
+# Style Guidelines
 
-The design guidelines have quite a high abstraction level. These style guidelines are more concrete and easier to apply, and also more opinionated.
+The design guidelines have quite a high abstraction level. These style guidelines are more concrete and easier to apply, and also more opinionated. We value clean code and consistency, and those are prerequisites for us to include new code in the repository. Before proposing a change, please read these guidelines and take some time to familiarize yourself with the style of the existing codebase.
 
-### General
+## Solidity code
 
-#### G0 - Default to Solidity's official style guide.
+In order to be consistent with all the other Solidity projects, we follow the
+[official recommendations documented in the Solidity style guide](http://solidity.readthedocs.io/en/latest/style-guide.html).
 
-Follow the official Solidity style guide: https://solidity.readthedocs.io/en/latest/style-guide.html
+Any exception or additions specific to our project are documented below.
 
-#### G1 - No Magic Constants
+* Try to avoid acronyms and abbreviations.
 
-Avoid constants in the code as much as possible. Magic strings are also magic constants.
+* All state variables should be private.
 
-#### G2 - Code that Fails Early
+* Private state variables should have an underscore prefix.
 
-We ask our code to fail as soon as possible when an unexpected input was provided or unexpected state was found.
+    ```
+    contract TestContract {
+      uint256 private _privateVar;
+      uint256 internal _internalVar;
+    }
+    ```
 
-#### G3 - Internal Amounts Must be Signed Integers and Represent the Smallest Units.
+* Parameters must not be prefixed with an underscore.
 
-Avoid representation errors by always dealing with weis when handling ether. GUIs can convert to more human-friendly representations. Use Signed Integers (int) to prevent underflow problems.
+    ```
+    function test(uint256 testParameter1, uint256 testParameter2) {
+    ...
+    }
+    ```
 
+* Internal and private functions should have an underscore prefix.
 
-### Testing
+    ```
+    function _testInternal() internal {
+      ...
+    }
+    ```
 
-#### T1 - Tests Must be Written Elegantly
+    ```
+    function _testPrivate() private {
+      ...
+    }
+    ```
 
-Style guidelines are not relaxed for tests. Tests are a good way to show how to use the library, and maintaining them is extremely necessary.
+* Events should be emitted immediately after the state change that they
+  represent, and consequently they should be named in past tense.
 
-Don't write long tests, write helper functions to make them be as short and concise as possible (they should take just a few lines each), and use good variable names.
+    ```
+    function _burn(address who, uint256 value) internal {
+      super._burn(who, value);
+      emit TokensBurned(who, value);
+    }
+    ```
 
-#### T2 - Tests Must not be Random
+  Some standards (e.g. ERC20) use present tense, and in those cases the
+  standard specification prevails.
+  
+* Interface names should have a capital I prefix.
 
-Inputs for tests should not be generated randomly. Accounts used to create test contracts are an exception, those can be random. Also, the type and structure of outputs should be checked.
+    ```
+    interface IERC777 {
+    ```
+
+
+## Tests
+
+* Tests Must be Written Elegantly
+
+    Tests are a good way to show how to use the library, and maintaining them is extremely necessary. Don't write long tests, write helper functions to make them be as short and concise as possible (they should take just a few lines each), and use good variable names.
+
+* Tests Must not be Random
+
+    Inputs for tests should not be generated randomly. Accounts used to create test contracts are an exception, those can be random. Also, the type and structure of outputs should be checked.

README.md

@@ -1,4 +1,4 @@
-# <img src="logo.png" alt="OpenZeppelin" height="40px">
+# <img src="logo.svg" alt="OpenZeppelin" height="40px">
 
 [![Docs](https://img.shields.io/badge/docs-%F0%9F%93%84-blue)](https://docs.openzeppelin.com/contracts)
 [![NPM Package](https://img.shields.io/npm/v/@openzeppelin/contracts.svg)](https://www.npmjs.org/package/@openzeppelin/contracts)
@@ -44,7 +44,7 @@ To keep your system secure, you should **always** use the installed code as-is,
 
 ## Learn More
 
-The guides in the sidebar will teach about different concepts, and how to use the related contracts that OpenZeppelin Contracts provides:
+The guides in the [docs site](https://docs.openzeppelin.com/contracts) will teach about different concepts, and how to use the related contracts that OpenZeppelin Contracts provides:
 
 * [Access Control](https://docs.openzeppelin.com/contracts/access-control): decide who can perform each of the actions on your system.
 * [Tokens](https://docs.openzeppelin.com/contracts/tokens): create tradeable assets or collectives, and distribute them via [Crowdsales](https://docs.openzeppelin.com/contracts/crowdsales).

contracts/token/ERC20/ERC20Snapshot.sol

@@ -104,28 +104,25 @@ abstract contract ERC20Snapshot is ERC20 {
         return snapshotted ? value : totalSupply();
     }
 
-    // _transfer, _mint and _burn are the only functions where the balances are modified, so it is there that the
-    // snapshots are updated. Note that the update happens _before_ the balance change, with the pre-modified value.
-    // The same is true for the total supply and _mint and _burn.
-    function _transfer(address from, address to, uint256 value) internal virtual override {
-        _updateAccountSnapshot(from);
-        _updateAccountSnapshot(to);
 
-        super._transfer(from, to, value);
-    }
+    // Update balance and/or total supply snapshots before the values are modified. This is implemented
+    // in the _beforeTokenTransfer hook, which is executed for _mint, _burn, and _transfer operations.
+    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
+      super._beforeTokenTransfer(from, to, amount);
 
-    function _mint(address account, uint256 value) internal virtual override {
-        _updateAccountSnapshot(account);
+      if (from == address(0)) {
+        // mint
+        _updateAccountSnapshot(to);
         _updateTotalSupplySnapshot();
-
-        super._mint(account, value);
-    }
-
-    function _burn(address account, uint256 value) internal virtual override {
-        _updateAccountSnapshot(account);
+      } else if (to == address(0)) {
+        // burn
+        _updateAccountSnapshot(from);
         _updateTotalSupplySnapshot();
-
-        super._burn(account, value);
+      } else {
+        // transfer
+        _updateAccountSnapshot(from);
+        _updateAccountSnapshot(to);
+      }
     }
 
     function _valueAt(uint256 snapshotId, Snapshots storage snapshots)

package-lock.json

@@ -1465,9 +1465,9 @@
       "dev": true
     },
     "@openzeppelin/gsn-helpers": {
-      "version": "0.2.3",
-      "resolved": "https://registry.npmjs.org/@openzeppelin/gsn-helpers/-/gsn-helpers-0.2.3.tgz",
-      "integrity": "sha512-NRPFy6rbMfQWgvHW6jlJ0zg5L3wHrCZ9wKO2CmjszUZBwR3K1n8OfKNAXWEYiUArz0c7tP3qZuI7ifGb6dZvJg==",
+      "version": "0.2.4",
+      "resolved": "https://registry.npmjs.org/@openzeppelin/gsn-helpers/-/gsn-helpers-0.2.4.tgz",
+      "integrity": "sha512-gxAXoJvmtBiiJgC1yjX5s+e08WuytH2yhvp7C8tA9Gsac3P9grdF0xJaw7wfZnhwtby4A7J7+LHKbaZhYichvw==",
       "dev": true,
       "requires": {
         "axios": "^0.19.0",
@@ -1496,11 +1496,20 @@
           }
         },
         "lodash": {
-          "version": "4.17.15",
-          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
-          "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
+          "version": "4.17.20",
+          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.20.tgz",
+          "integrity": "sha512-PlhdFcillOINfeV7Ni6oF1TAEayyZBoZ8bcshTHqOYJYlrqzRK5hagpagky5o4HfCzzd1TRkXPMFq6cKk9rGmA==",
           "dev": true
         },
+        "rimraf": {
+          "version": "2.7.1",
+          "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-2.7.1.tgz",
+          "integrity": "sha512-uWjbaKIK3T1OSVptzX7Nl6PvQ3qAGtKEtVRjRuazjfL3Bx5eI409VZSqgND+4UNnmzLVdPj9FqFJNPqBZFve4w==",
+          "dev": true,
+          "requires": {
+            "glob": "^7.1.3"
+          }
+        },
         "tmp": {
           "version": "0.1.0",
           "resolved": "https://registry.npmjs.org/tmp/-/tmp-0.1.0.tgz",
@@ -1508,25 +1517,14 @@
           "dev": true,
           "requires": {
             "rimraf": "^2.6.3"
-          },
-          "dependencies": {
-            "rimraf": {
-              "version": "2.7.1",
-              "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-2.7.1.tgz",
-              "integrity": "sha512-uWjbaKIK3T1OSVptzX7Nl6PvQ3qAGtKEtVRjRuazjfL3Bx5eI409VZSqgND+4UNnmzLVdPj9FqFJNPqBZFve4w==",
-              "dev": true,
-              "requires": {
-                "glob": "^7.1.3"
-              }
-            }
           }
         }
       }
     },
     "@openzeppelin/gsn-provider": {
-      "version": "0.1.10",
-      "resolved": "https://registry.npmjs.org/@openzeppelin/gsn-provider/-/gsn-provider-0.1.10.tgz",
-      "integrity": "sha512-DKuU5zVE1I+cbPWFb9kSTtIZ2OTnPfCedseBIbGMgaZM8HhW1O4iSlrqXWk+lQprQn/DF4DcxPgMPjDau2zp5w==",
+      "version": "0.1.11",
+      "resolved": "https://registry.npmjs.org/@openzeppelin/gsn-provider/-/gsn-provider-0.1.11.tgz",
+      "integrity": "sha512-UeAsBj1ICk883A3CQNdZcoeowh01WE6lqOXJbMoXLFtZJmtnAzXNocup38aXi75W03L11cua5tr4PWh1nwMhDg==",
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@@ -1548,50 +1546,35 @@
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           "dev": true
         },
+        "elliptic": {
+          "version": "6.5.3",
+          "resolved": "https://registry.npmjs.org/elliptic/-/elliptic-6.5.3.tgz",
+          "integrity": "sha512-IMqzv5wNQf+E6aHeIqATs0tOLeOTwj1QKbRcS3jBbYkl5oLAserA8yJTT7/VyHUYG91PRmPyeQDObKLPpeS4dw==",
+          "dev": true,
+          "requires": {
+            "bn.js": "^4.4.0",
+            "brorand": "^1.0.1",
+            "hash.js": "^1.0.0",
+            "hmac-drbg": "^1.0.0",
+            "inherits": "^2.0.1",
+            "minimalistic-assert": "^1.0.0",
+            "minimalistic-crypto-utils": "^1.0.0"
+          }
+        },
         "ethereumjs-util": {
-          "version": "6.2.0",
-          "resolved": "https://registry.npmjs.org/ethereumjs-util/-/ethereumjs-util-6.2.0.tgz",
-          "integrity": "sha512-vb0XN9J2QGdZGIEKG2vXM+kUdEivUfU6Wmi5y0cg+LRhDYKnXIZ/Lz7XjFbHRR9VIKq2lVGLzGBkA++y2nOdOQ==",
+          "version": "6.2.1",
+          "resolved": "https://registry.npmjs.org/ethereumjs-util/-/ethereumjs-util-6.2.1.tgz",
+          "integrity": "sha512-W2Ktez4L01Vexijrm5EB6w7dg4n/TgpoYU4avuT5T3Vmnw/eCRtiBrJfQYS/DCSvDIOLn2k57GcHdeBcgVxAqw==",
           "dev": true,
           "requires": {
             "@types/bn.js": "^4.11.3",
             "bn.js": "^4.11.0",
             "create-hash": "^1.1.2",
+            "elliptic": "^6.5.2",
+            "ethereum-cryptography": "^0.1.3",
             "ethjs-util": "0.1.6",
-            "keccak": "^2.0.0",
-            "rlp": "^2.2.3",
-            "secp256k1": "^3.0.1"
+            "rlp": "^2.2.3"
           }
-        },
-        "inherits": {
-          "version": "2.0.4",
-          "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
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-          "dev": true
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-          "dev": true,
-          "requires": {
-            "bindings": "^1.5.0",
-            "inherits": "^2.0.4",
-            "nan": "^2.14.0",
-            "safe-buffer": "^5.2.0"
-          }
-        },
-        "nan": {
-          "version": "2.14.1",
-          "resolved": "https://registry.npmjs.org/nan/-/nan-2.14.1.tgz",
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-          "dev": true
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-          "dev": true
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@@ -4313,9 +4296,9 @@
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     "@types/pbkdf2": {
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-      "resolved": "https://registry.npmjs.org/@types/pbkdf2/-/pbkdf2-3.0.0.tgz",
-      "integrity": "sha512-6J6MHaAlBJC/eVMy9jOwj9oHaprfutukfW/Dyt0NEnpQ/6HN6YQrpvLwzWdWDeWZIdenjGHlbYDzyEODO5Z+2Q==",
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+      "resolved": "https://registry.npmjs.org/@types/pbkdf2/-/pbkdf2-3.1.0.tgz",
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       "dev": true,
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@@ -4825,9 +4808,9 @@
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+          "version": "1.1.1",
+          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.1.tgz",
+          "integrity": "sha512-1+QkEcxiLlB7VEyFtyBg94e08OAsvq7FUBgApTq/w2ymCLyKJgDPsybBENVtA7XCQEgEXxKPonG+mvYRxh/LIg==",
           "dev": true,
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@@ -4931,39 +4914,12 @@
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-      "resolved": "https://registry.npmjs.org/axios/-/axios-0.19.0.tgz",
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+      "version": "0.19.2",
+      "resolved": "https://registry.npmjs.org/axios/-/axios-0.19.2.tgz",
+      "integrity": "sha512-fjgm5MvRHLhx+osE2xoekY70AhARk3a6hkN+3Io1jc00jtquGvxYlKlsFUhmUET0V5te6CcZI7lcv2Ym61mjHA==",
       "dev": true,
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-        "is-buffer": "^2.0.2"
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-          "dev": true,
-          "requires": {
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-        "follow-redirects": {
-          "version": "1.5.10",
-          "resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.5.10.tgz",
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-          "dev": true,
-          "requires": {
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-          }
-        },
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-          "dev": true
-        }
+        "follow-redirects": "1.5.10"
       }
     },
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@@ -6682,9 +6638,9 @@
           "dev": true
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           "dev": true,
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@@ -7223,9 +7179,9 @@
       "dev": true
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-      "resolved": "https://registry.npmjs.org/eth-crypto/-/eth-crypto-1.5.2.tgz",
-      "integrity": "sha512-xhu7rt3CdNKSQ5VcqiFwfp50YVtc1+VPiqYEfMa8Omx9rGn5QHdIjImSoEnlej3VbfHv25Kvpu6A5oPoSI6iUA==",
+      "version": "1.6.0",
+      "resolved": "https://registry.npmjs.org/eth-crypto/-/eth-crypto-1.6.0.tgz",
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       "dev": true,
       "requires": {
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@@ -7234,8 +7190,8 @@
         "eth-lib": "0.2.8",
         "ethereumjs-tx": "2.1.2",
         "ethereumjs-util": "6.2.0",
-        "ethers": "4.0.44",
-        "secp256k1": "3.8.0"
+        "ethers": "4.0.47",
+        "secp256k1": "4.0.1"
       },
       "dependencies": {
         "@types/bn.js": {
@@ -7259,9 +7215,9 @@
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-        "strip-json-comments": {
-          "version": "3.0.1",
-          "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-3.0.1.tgz",
-          "integrity": "sha512-VTyMAUfdm047mwKl+u79WIdrZxtFtn+nBxHeb844XBQ9uMNTuTHdx2hc5RiAJYqwTj3wc/xe5HLSdJSkJ+WfZw==",
-          "dev": true
-        },
         "supports-color": {
           "version": "7.1.0",
           "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.1.0.tgz",
@@ -31927,9 +31952,9 @@
       }
     },
     "node-gyp-build": {
-      "version": "4.2.2",
-      "resolved": "https://registry.npmjs.org/node-gyp-build/-/node-gyp-build-4.2.2.tgz",
-      "integrity": "sha512-Lqh7mrByWCM8Cf9UPqpeoVBBo5Ugx+RKu885GAzmLBVYjeywScxHXPGLa4JfYNZmcNGwzR0Glu5/9GaQZMFqyA==",
+      "version": "4.2.3",
+      "resolved": "https://registry.npmjs.org/node-gyp-build/-/node-gyp-build-4.2.3.tgz",
+      "integrity": "sha512-MN6ZpzmfNCRM+3t57PTJHgHyw/h4OWnZ6mR8P5j/uZtqQr46RRuDE/P+g3n0YR/AiYXeWixZZzaip77gdICfRg==",
       "dev": true
     },
     "nofilter": {
@@ -32744,9 +32769,9 @@
           "dev": true
         },
         "is-regex": {
-          "version": "1.1.0",
-          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.0.tgz",
-          "integrity": "sha512-iI97M8KTWID2la5uYXlkbSDQIg4F6o1sYboZKKTDpnDQMLtUL86zxhgDet3Q2SriaYsyGqZ6Mn2SjbRKeLHdqw==",
+          "version": "1.1.1",
+          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.1.tgz",
+          "integrity": "sha512-1+QkEcxiLlB7VEyFtyBg94e08OAsvq7FUBgApTq/w2ymCLyKJgDPsybBENVtA7XCQEgEXxKPonG+mvYRxh/LIg==",
           "dev": true,
           "requires": {
             "has-symbols": "^1.0.1"
@@ -33428,10 +33453,13 @@
       }
     },
     "serialize-javascript": {
-      "version": "3.0.0",
-      "resolved": "https://registry.npmjs.org/serialize-javascript/-/serialize-javascript-3.0.0.tgz",
-      "integrity": "sha512-skZcHYw2vEX4bw90nAr2iTTsz6x2SrHEnfxgKYmZlvJYBEZrvbKtobJWlQ20zczKb3bsHHXXTYt48zBA7ni9cw==",
-      "dev": true
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/serialize-javascript/-/serialize-javascript-4.0.0.tgz",
+      "integrity": "sha512-GaNA54380uFefWghODBWEGisLZFj00nS5ACs6yHa9nLqlLpVLO8ChDGeKRjZnV4Nh4n0Qi7nhYZD/9fCPzEqkw==",
+      "dev": true,
+      "requires": {
+        "randombytes": "^2.1.0"
+      }
     },
     "serve-index": {
       "version": "1.9.1",
@@ -33928,12 +33956,12 @@
       }
     },
     "solhint": {
-      "version": "3.0.0",
-      "resolved": "https://registry.npmjs.org/solhint/-/solhint-3.0.0.tgz",
-      "integrity": "sha512-z6JBNrtWZ51g/tkuZGc0ywQVskRqIGjXppR4g30bjPgOrxSBWJp3qX2pcI9+FbSI3uu1RqqbZ89CeURkZUF+RA==",
+      "version": "3.2.0",
+      "resolved": "https://registry.npmjs.org/solhint/-/solhint-3.2.0.tgz",
+      "integrity": "sha512-BGp7JnnoLzknGC/arcH33oN/LjOz0hKgdauOcBOO5jNjhjnPQ3cAacSMH64fWYShAg5+HYQaSRubInpSKSvzLg==",
       "dev": true,
       "requires": {
-        "@solidity-parser/parser": "^0.6.0",
+        "@solidity-parser/parser": "^0.7.0",
         "ajv": "^6.6.1",
         "antlr4": "4.7.1",
         "ast-parents": "0.0.1",
@@ -33951,9 +33979,9 @@
       },
       "dependencies": {
         "@solidity-parser/parser": {
-          "version": "0.6.0",
-          "resolved": "https://registry.npmjs.org/@solidity-parser/parser/-/parser-0.6.0.tgz",
-          "integrity": "sha512-RiJXfS22frulogcfQCFhbKrd5ATu6P4tYUv/daChiIh6VHyKQ1kkVZVfX6aP7c2YGU/Bf9RwGNKdwLjfpaoqYQ==",
+          "version": "0.7.0",
+          "resolved": "https://registry.npmjs.org/@solidity-parser/parser/-/parser-0.7.0.tgz",
+          "integrity": "sha512-YJ333ezgd9slnwCpFQVfsBcYsTcLWZRpVswlKgS82YDZPzzNtVnkEs5DX5+jMsu8PNnVxwZuxC6ucukima9x6w==",
           "dev": true
         },
         "acorn": {
@@ -33963,9 +33991,9 @@
           "dev": true
         },
         "ajv": {
-          "version": "6.12.2",
-          "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.2.tgz",
-          "integrity": "sha512-k+V+hzjm5q/Mr8ef/1Y9goCmlsK4I6Sm74teeyGvFk1XrOsbsKLjEdrvny42CZ+a8sXbk8KWpY/bDwS+FLL2UQ==",
+          "version": "6.12.4",
+          "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.4.tgz",
+          "integrity": "sha512-eienB2c9qVQs2KWexhkrdMLVDoIQCz5KSeLxwg9Lzk4DOfBtIK9PQwwufcsn1jjGuf9WZmqPMbGxOzfcuphJCQ==",
           "dev": true,
           "requires": {
             "fast-deep-equal": "^3.1.1",
@@ -34069,9 +34097,9 @@
           }
         },
         "fast-deep-equal": {
-          "version": "3.1.1",
-          "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.1.tgz",
-          "integrity": "sha512-8UEa58QDLauDNfpbrX55Q9jrGHThw2ZMdOky5Gl1CDtVeJDPVrG4Jxx1N8jw2gkWaff5UUuX1KJd+9zGe2B+ZA==",
+          "version": "3.1.3",
+          "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
+          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==",
           "dev": true
         },
         "glob": {
@@ -34124,6 +34152,12 @@
           "requires": {
             "ansi-regex": "^3.0.0"
           }
+        },
+        "strip-json-comments": {
+          "version": "2.0.1",
+          "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-2.0.1.tgz",
+          "integrity": "sha1-PFMZQukIwml8DsNEhYwobHygpgo=",
+          "dev": true
         }
       }
     },
@@ -34824,9 +34858,9 @@
           "dev": true
         },
         "is-regex": {
-          "version": "1.1.0",
-          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.0.tgz",
-          "integrity": "sha512-iI97M8KTWID2la5uYXlkbSDQIg4F6o1sYboZKKTDpnDQMLtUL86zxhgDet3Q2SriaYsyGqZ6Mn2SjbRKeLHdqw==",
+          "version": "1.1.1",
+          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.1.tgz",
+          "integrity": "sha512-1+QkEcxiLlB7VEyFtyBg94e08OAsvq7FUBgApTq/w2ymCLyKJgDPsybBENVtA7XCQEgEXxKPonG+mvYRxh/LIg==",
           "dev": true,
           "requires": {
             "has-symbols": "^1.0.1"
@@ -34938,9 +34972,9 @@
           "dev": true
         },
         "is-regex": {
-          "version": "1.1.0",
-          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.0.tgz",
-          "integrity": "sha512-iI97M8KTWID2la5uYXlkbSDQIg4F6o1sYboZKKTDpnDQMLtUL86zxhgDet3Q2SriaYsyGqZ6Mn2SjbRKeLHdqw==",
+          "version": "1.1.1",
+          "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.1.1.tgz",
+          "integrity": "sha512-1+QkEcxiLlB7VEyFtyBg94e08OAsvq7FUBgApTq/w2ymCLyKJgDPsybBENVtA7XCQEgEXxKPonG+mvYRxh/LIg==",
           "dev": true,
           "requires": {
             "has-symbols": "^1.0.1"
@@ -34991,9 +35025,9 @@
       }
     },
     "strip-json-comments": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-2.0.1.tgz",
-      "integrity": "sha1-PFMZQukIwml8DsNEhYwobHygpgo=",
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-3.0.1.tgz",
+      "integrity": "sha512-VTyMAUfdm047mwKl+u79WIdrZxtFtn+nBxHeb844XBQ9uMNTuTHdx2hc5RiAJYqwTj3wc/xe5HLSdJSkJ+WfZw==",
       "dev": true
     },
     "supports-color": {
@@ -37413,21 +37447,112 @@
       }
     },
     "yargs-unparser": {
-      "version": "1.6.0",
-      "resolved": "https://registry.npmjs.org/yargs-unparser/-/yargs-unparser-1.6.0.tgz",
-      "integrity": "sha512-W9tKgmSn0DpSatfri0nx52Joq5hVXgeLiqR/5G0sZNDoLZFOr/xjBUDcShCOGNsBnEMNo1KAMBkTej1Hm62HTw==",
+      "version": "1.6.1",
+      "resolved": "https://registry.npmjs.org/yargs-unparser/-/yargs-unparser-1.6.1.tgz",
+      "integrity": "sha512-qZV14lK9MWsGCmcr7u5oXGH0dbGqZAIxTDrWXZDo5zUr6b6iUmelNKO6x6R1dQT24AH3LgRxJpr8meWy2unolA==",
       "dev": true,
       "requires": {
+        "camelcase": "^5.3.1",
+        "decamelize": "^1.2.0",
         "flat": "^4.1.0",
-        "lodash": "^4.17.15",
-        "yargs": "^13.3.0"
+        "is-plain-obj": "^1.1.0",
+        "yargs": "^14.2.3"
       },
       "dependencies": {
-        "lodash": {
-          "version": "4.17.15",
-          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
-          "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
+        "ansi-regex": {
+          "version": "4.1.0",
+          "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-4.1.0.tgz",
+          "integrity": "sha512-1apePfXM1UOSqw0o9IiFAovVz9M5S1Dg+4TrDwfMewQ6p/rmMueb7tWZjQ1rx4Loy1ArBggoqGpfqqdI4rondg==",
+          "dev": true
+        },
+        "find-up": {
+          "version": "3.0.0",
+          "resolved": "https://registry.npmjs.org/find-up/-/find-up-3.0.0.tgz",
+          "integrity": "sha512-1yD6RmLI1XBfxugvORwlck6f75tYL+iR0jqwsOrOxMZyGYqUuDhJ0l4AXdO1iX/FTs9cBAMEk1gWSEx1kSbylg==",
+          "dev": true,
+          "requires": {
+            "locate-path": "^3.0.0"
+          }
+        },
+        "get-caller-file": {
+          "version": "2.0.5",
+          "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-2.0.5.tgz",
+          "integrity": "sha512-DyFP3BM/3YHTQOCUL/w0OZHR0lpKeGrxotcHWcqNEdnltqFwXVfhEBQ94eIo34AfQpo0rGki4cyIiftY06h2Fg==",
+          "dev": true
+        },
+        "locate-path": {
+          "version": "3.0.0",
+          "resolved": "https://registry.npmjs.org/locate-path/-/locate-path-3.0.0.tgz",
+          "integrity": "sha512-7AO748wWnIhNqAuaty2ZWHkQHRSNfPVIsPIfwEOWO22AmaoVrWavlOcMR5nzTLNYvp36X220/maaRsrec1G65A==",
+          "dev": true,
+          "requires": {
+            "p-locate": "^3.0.0",
+            "path-exists": "^3.0.0"
+          }
+        },
+        "p-locate": {
+          "version": "3.0.0",
+          "resolved": "https://registry.npmjs.org/p-locate/-/p-locate-3.0.0.tgz",
+          "integrity": "sha512-x+12w/To+4GFfgJhBEpiDcLozRJGegY+Ei7/z0tSLkMmxGZNybVMSfWj9aJn8Z5Fc7dBUNJOOVgPv2H7IwulSQ==",
+          "dev": true,
+          "requires": {
+            "p-limit": "^2.0.0"
+          }
+        },
+        "require-main-filename": {
+          "version": "2.0.0",
+          "resolved": "https://registry.npmjs.org/require-main-filename/-/require-main-filename-2.0.0.tgz",
+          "integrity": "sha512-NKN5kMDylKuldxYLSUfrbo5Tuzh4hd+2E8NPPX02mZtn1VuREQToYe/ZdlJy+J3uCpfaiGF05e7B8W0iXbQHmg==",
           "dev": true
+        },
+        "string-width": {
+          "version": "3.1.0",
+          "resolved": "https://registry.npmjs.org/string-width/-/string-width-3.1.0.tgz",
+          "integrity": "sha512-vafcv6KjVZKSgz06oM/H6GDBrAtz8vdhQakGjFIvNrHA6y3HCF1CInLy+QLq8dTJPQ1b+KDUqDFctkdRW44e1w==",
+          "dev": true,
+          "requires": {
+            "emoji-regex": "^7.0.1",
+            "is-fullwidth-code-point": "^2.0.0",
+            "strip-ansi": "^5.1.0"
+          }
+        },
+        "strip-ansi": {
+          "version": "5.2.0",
+          "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-5.2.0.tgz",
+          "integrity": "sha512-DuRs1gKbBqsMKIZlrffwlug8MHkcnpjs5VPmL1PAh+mA30U0DTotfDZ0d2UUsXpPmPmMMJ6W773MaA3J+lbiWA==",
+          "dev": true,
+          "requires": {
+            "ansi-regex": "^4.1.0"
+          }
+        },
+        "yargs": {
+          "version": "14.2.3",
+          "resolved": "https://registry.npmjs.org/yargs/-/yargs-14.2.3.tgz",
+          "integrity": "sha512-ZbotRWhF+lkjijC/VhmOT9wSgyBQ7+zr13+YLkhfsSiTriYsMzkTUFP18pFhWwBeMa5gUc1MzbhrO6/VB7c9Xg==",
+          "dev": true,
+          "requires": {
+            "cliui": "^5.0.0",
+            "decamelize": "^1.2.0",
+            "find-up": "^3.0.0",
+            "get-caller-file": "^2.0.1",
+            "require-directory": "^2.1.1",
+            "require-main-filename": "^2.0.0",
+            "set-blocking": "^2.0.0",
+            "string-width": "^3.0.0",
+            "which-module": "^2.0.0",
+            "y18n": "^4.0.0",
+            "yargs-parser": "^15.0.1"
+          }
+        },
+        "yargs-parser": {
+          "version": "15.0.1",
+          "resolved": "https://registry.npmjs.org/yargs-parser/-/yargs-parser-15.0.1.tgz",
+          "integrity": "sha512-0OAMV2mAZQrs3FkNpDQcBk1x5HXb8X4twADss4S0Iuk+2dGnLOE/fRHrsYm542GduMveyA77OF4wrNJuanRCWw==",
+          "dev": true,
+          "requires": {
+            "camelcase": "^5.0.0",
+            "decamelize": "^1.2.0"
+          }
         }
       }
     },

test/token/ERC1155/ERC1155.behavior.js

@@ -92,6 +92,14 @@ function shouldBehaveLikeERC1155 ([minter, firstTokenHolder, secondTokenHolder,
           ),
           'ERC1155: accounts and ids length mismatch'
         );
+
+        await expectRevert(
+          this.token.balanceOfBatch(
+            [firstTokenHolder, secondTokenHolder],
+            [firstTokenId, secondTokenId, unknownTokenId]
+          ),
+          'ERC1155: accounts and ids length mismatch'
+        );
       });
 
       it('reverts when one of the addresses is the zero address', async function () {
@@ -143,6 +151,18 @@ function shouldBehaveLikeERC1155 ([minter, firstTokenHolder, secondTokenHolder,
           expect(result[1]).to.be.a.bignumber.equal(firstAmount);
           expect(result[2]).to.be.a.bignumber.equal('0');
         });
+
+        it('returns multiple times the balance of the same address when asked', async function () {
+          const result = await this.token.balanceOfBatch(
+            [firstTokenHolder, secondTokenHolder, firstTokenHolder],
+            [firstTokenId, secondTokenId, firstTokenId]
+          );
+          expect(result).to.be.an('array');
+          expect(result[0]).to.be.a.bignumber.equal(result[2]);
+          expect(result[0]).to.be.a.bignumber.equal(firstAmount);
+          expect(result[1]).to.be.a.bignumber.equal(secondAmount);
+          expect(result[2]).to.be.a.bignumber.equal(firstAmount);
+        });
       });
     });
 
@@ -298,8 +318,11 @@ function shouldBehaveLikeERC1155 ([minter, firstTokenHolder, secondTokenHolder,
           });
 
           it('preserves operator\'s balances not involved in the transfer', async function () {
-            const balance = await this.token.balanceOf(proxy, firstTokenId);
-            expect(balance).to.be.a.bignumber.equal('0');
+            const balance1 = await this.token.balanceOf(proxy, firstTokenId);
+            expect(balance1).to.be.a.bignumber.equal('0');
+
+            const balance2 = await this.token.balanceOf(proxy, secondTokenId);
+            expect(balance2).to.be.a.bignumber.equal('0');
           });
         });
       });
@@ -464,6 +487,16 @@ function shouldBehaveLikeERC1155 ([minter, firstTokenHolder, secondTokenHolder,
           ),
           'ERC1155: ids and amounts length mismatch'
         );
+
+        await expectRevert(
+          this.token.safeBatchTransferFrom(
+            multiTokenHolder, recipient,
+            [firstTokenId, secondTokenId],
+            [firstAmount],
+            '0x', { from: multiTokenHolder }
+          ),
+          'ERC1155: ids and amounts length mismatch'
+        );
       });
 
       it('reverts when transferring to zero address', async function () {
@@ -684,6 +717,41 @@ function shouldBehaveLikeERC1155 ([minter, firstTokenHolder, secondTokenHolder,
         });
       });
 
+      context('to a receiver contract that reverts only on single transfers', function () {
+        beforeEach(async function () {
+          this.receiver = await ERC1155ReceiverMock.new(
+            RECEIVER_SINGLE_MAGIC_VALUE, true,
+            RECEIVER_BATCH_MAGIC_VALUE, false,
+          );
+
+          this.toWhom = this.receiver.address;
+          this.transferReceipt = await this.token.safeBatchTransferFrom(
+            multiTokenHolder, this.receiver.address,
+            [firstTokenId, secondTokenId],
+            [firstAmount, secondAmount],
+            '0x', { from: multiTokenHolder },
+          );
+          ({ logs: this.transferLogs } = this.transferReceipt);
+        });
+
+        batchTransferWasSuccessful.call(this, {
+          operator: multiTokenHolder,
+          from: multiTokenHolder,
+          ids: [firstTokenId, secondTokenId],
+          values: [firstAmount, secondAmount],
+        });
+
+        it('should call onERC1155BatchReceived', async function () {
+          await expectEvent.inTransaction(this.transferReceipt.tx, ERC1155ReceiverMock, 'BatchReceived', {
+            operator: multiTokenHolder,
+            from: multiTokenHolder,
+            // ids: [firstTokenId, secondTokenId],
+            // values: [firstAmount, secondAmount],
+            data: null,
+          });
+        });
+      });
+
       context('to a contract that does not implement the required function', function () {
         it('reverts', async function () {
           const invalidReceiver = this.token;

test/token/ERC1155/ERC1155.test.js

@@ -28,7 +28,7 @@ describe('ERC1155', function () {
     const mintAmounts = [new BN(5000), new BN(10000), new BN(42195)];
     const burnAmounts = [new BN(5000), new BN(9001), new BN(195)];
 
-    const data = '0xcafebabe';
+    const data = '0x12345678';
 
     describe('_mint', function () {
       it('reverts with a zero destination address', async function () {
@@ -72,6 +72,11 @@ describe('ERC1155', function () {
           this.token.mintBatch(tokenBatchHolder, tokenBatchIds, mintAmounts.slice(1), data),
           'ERC1155: ids and amounts length mismatch'
         );
+
+        await expectRevert(
+          this.token.mintBatch(tokenBatchHolder, tokenBatchIds.slice(1), mintAmounts, data),
+          'ERC1155: ids and amounts length mismatch'
+        );
       });
 
       context('with minted batch of tokens', function () {
@@ -121,6 +126,21 @@ describe('ERC1155', function () {
         );
       });
 
+      it('reverts when burning more than available tokens', async function () {
+        await this.token.mint(
+          tokenHolder,
+          tokenId,
+          mintAmount,
+          data,
+          { from: operator }
+        );
+
+        await expectRevert(
+          this.token.burn(tokenHolder, tokenId, mintAmount.addn(1)),
+          'ERC1155: burn amount exceeds balance'
+        );
+      });
+
       context('with minted-then-burnt tokens', function () {
         beforeEach(async function () {
           await this.token.mint(tokenHolder, tokenId, mintAmount, data);
@@ -164,6 +184,11 @@ describe('ERC1155', function () {
           this.token.burnBatch(tokenBatchHolder, tokenBatchIds, burnAmounts.slice(1)),
           'ERC1155: ids and amounts length mismatch'
         );
+
+        await expectRevert(
+          this.token.burnBatch(tokenBatchHolder, tokenBatchIds.slice(1), burnAmounts),
+          'ERC1155: ids and amounts length mismatch'
+        );
       });
 
       it('reverts when burning a non-existent token id', async function () {

test/token/ERC1155/ERC1155Holder.test.js

@@ -8,41 +8,52 @@ const { expect } = require('chai');
 
 describe('ERC1155Holder', function () {
   const [creator] = accounts;
+  const uri = 'https://token-cdn-domain/{id}.json';
+  const multiTokenIds = [new BN(1), new BN(2), new BN(3)];
+  const multiTokenAmounts = [new BN(1000), new BN(2000), new BN(3000)];
+  const transferData = '0x12345678';
+
+  beforeEach(async function () {
+    this.multiToken = await ERC1155Mock.new(uri, { from: creator });
+    this.holder = await ERC1155Holder.new();
+    await this.multiToken.mintBatch(creator, multiTokenIds, multiTokenAmounts, '0x', { from: creator });
+  });
 
-  it('receives ERC1155 tokens', async function () {
-    const uri = 'https://token-cdn-domain/{id}.json';
-
-    const multiToken = await ERC1155Mock.new(uri, { from: creator });
-    const multiTokenIds = [new BN(1), new BN(2), new BN(3)];
-    const multiTokenAmounts = [new BN(1000), new BN(2000), new BN(3000)];
-    await multiToken.mintBatch(creator, multiTokenIds, multiTokenAmounts, '0x', { from: creator });
-
-    const transferData = '0xf00dbabe';
-
-    const holder = await ERC1155Holder.new();
-
-    await multiToken.safeTransferFrom(
+  it('receives ERC1155 tokens from a single ID', async function () {
+    await this.multiToken.safeTransferFrom(
       creator,
-      holder.address,
+      this.holder.address,
       multiTokenIds[0],
       multiTokenAmounts[0],
       transferData,
       { from: creator },
     );
 
-    expect(await multiToken.balanceOf(holder.address, multiTokenIds[0])).to.be.bignumber.equal(multiTokenAmounts[0]);
+    expect(await this.multiToken.balanceOf(this.holder.address, multiTokenIds[0]))
+      .to.be.bignumber.equal(multiTokenAmounts[0]);
 
-    await multiToken.safeBatchTransferFrom(
+    for (let i = 1; i < multiTokenIds.length; i++) {
+      expect(await this.multiToken.balanceOf(this.holder.address, multiTokenIds[i])).to.be.bignumber.equal(new BN(0));
+    }
+  });
+
+  it('receives ERC1155 tokens from a multiple IDs', async function () {
+    for (let i = 0; i < multiTokenIds.length; i++) {
+      expect(await this.multiToken.balanceOf(this.holder.address, multiTokenIds[i])).to.be.bignumber.equal(new BN(0));
+    };
+
+    await this.multiToken.safeBatchTransferFrom(
       creator,
-      holder.address,
-      multiTokenIds.slice(1),
-      multiTokenAmounts.slice(1),
+      this.holder.address,
+      multiTokenIds,
+      multiTokenAmounts,
       transferData,
       { from: creator },
     );
 
-    for (let i = 1; i < multiTokenIds.length; i++) {
-      expect(await multiToken.balanceOf(holder.address, multiTokenIds[i])).to.be.bignumber.equal(multiTokenAmounts[i]);
+    for (let i = 0; i < multiTokenIds.length; i++) {
+      expect(await this.multiToken.balanceOf(this.holder.address, multiTokenIds[i]))
+        .to.be.bignumber.equal(multiTokenAmounts[i]);
     }
   });
 });

test/token/ERC20/ERC20Snapshot.test.js

@@ -134,7 +134,7 @@ describe('ERC20Snapshot', function () {
       context('with balance changes after the snapshot', function () {
         beforeEach(async function () {
           await this.token.transfer(recipient, new BN('10'), { from: initialHolder });
-          await this.token.mint(recipient, new BN('50'));
+          await this.token.mint(other, new BN('50'));
           await this.token.burn(initialHolder, new BN('20'));
         });