Merge branch 'sol-cov-fixes' of github.com:0xProject/0x-monorepo into sol-cov-fixes

* 'sol-cov-fixes' of github.com:0xProject/0x-monorepo: (49 commits)
  Add @return comments
  Import marshaller directly
  Update comment about ethers checksummed address behavior
  Add packages/coverage/.gitkeep file
  Update CI config and package.json to run @0xproject/utils tests on CI
  Update remaining CHANGELOG.json files
  Change amir picture
  Update CHANGELOG.json for contract-wrappers
  Update ethers typings for TypeScript 2.9.2
  Update CHANGELOG.json for base-contract
  Move some ethers-related types to typescript-typings/ethers
  Apply prettier
  Add strictArgumentEncodingCheck to BaseContract and use it in contract templates
  fix(monorepo-scripts): Fix typo in git tag command
  feat(monorepo-scripts): Add confirmation prompt before publishing
  fix comments and styling for MixinSignatureValidator
  Update TypeScript to version 2.9.2
  Use asm for hashEIP712Message, increment free memory pointer after asm hashing functions
  Fix comments, styling, and optimize hashOrder
  Remove assertion comments
  ...

4 files changed, 7 insertions, 3 deletions

diff --git a/packages/json-schemas/CHANGELOG.json b/packages/json-schemas/CHANGELOG.json
index 5ed7cc6ee..81f8e3220 100644
--- a/packages/json-schemas/CHANGELOG.json
+++ b/packages/json-schemas/CHANGELOG.json
@@ -5,6 +5,10 @@
             {
                 "note": "Allow for additional properties in txData schema",
                 "pr": 938
+            },
+            {
+                "note": "Change hexSchema to match `0x`",
+                "pr": 937
             }
         ]
     },
diff --git a/packages/json-schemas/package.json b/packages/json-schemas/package.json
index 4793fc0d5..6f0376d1b 100644
--- a/packages/json-schemas/package.json
+++ b/packages/json-schemas/package.json
@@ -70,7 +70,7 @@
         "shx": "^0.2.2",
         "tslint": "5.11.0",
         "typedoc": "0xProject/typedoc",
-        "typescript": "2.7.1"
+        "typescript": "2.9.2"
     },
     "publishConfig": {
         "access": "public"
diff --git a/packages/json-schemas/schemas/basic_type_schemas.ts b/packages/json-schemas/schemas/basic_type_schemas.ts
index 7565df9e0..301f9ec73 100644
--- a/packages/json-schemas/schemas/basic_type_schemas.ts
+++ b/packages/json-schemas/schemas/basic_type_schemas.ts
@@ -7,7 +7,7 @@ export const addressSchema = {
 export const hexSchema = {
     id: '/Hex',
     type: 'string',
-    pattern: '^0x([0-9a-f][0-9a-f])+$',
+    pattern: '^0x(([0-9a-f][0-9a-f])+)?$',
 };
 
 export const numberSchema = {
diff --git a/packages/json-schemas/test/schema_test.ts b/packages/json-schemas/test/schema_test.ts
index a7223dd36..891b4ce17 100644
--- a/packages/json-schemas/test/schema_test.ts
+++ b/packages/json-schemas/test/schema_test.ts
@@ -89,7 +89,7 @@ describe('Schema', () => {
             validateAgainstSchema(testCases, hexSchema);
         });
         it('should fail for invalid hex string', () => {
-            const testCases = ['0x', '0', '0xzzzzzzB11a196601eD2ce54B665CaFEca0347D42'];
+            const testCases = ['0', '0xzzzzzzB11a196601eD2ce54B665CaFEca0347D42'];
             const shouldFail = true;
             validateAgainstSchema(testCases, hexSchema, shouldFail);
         });