4 files changed, 62 insertions, 5 deletions
diff --git a/packages/contracts/package.json b/packages/contracts/package.json
index d6ca3727b..2495795dc 100644
--- a/packages/contracts/package.json
+++ b/packages/contracts/package.json
@@ -19,6 +19,7 @@
         "rebuild_and_test": "run-s build test",
         "test:coverage": "SOLIDITY_COVERAGE=true run-s build run_mocha coverage:report:text coverage:report:lcov",
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
+        "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register 'lib/test/**/*.js' --timeout 100000 --bail --exit",
         "compile": "sol-compiler",
         "clean": "shx rm -rf lib src/generated_contract_wrappers",
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
index ddcd78e93..eeddb9707 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
@@ -50,7 +50,35 @@ contract ERC20Proxy is
         address token = readAddress(assetData, 0);
 
         // Transfer tokens.
-        bool success = IERC20Token(token).transferFrom(from, to, amount);
+        // We do a raw call so we can check the success separate
+        // from the return data.
+        bool success = token.call(abi.encodeWithSelector(
+            IERC20Token(token).transferFrom.selector,
+            from,
+            to,
+            amount
+        ));
+        require(
+            success,
+            TRANSFER_FAILED
+        );
+        
+        // Check return data.
+        // If there is no return data, we assume the token incorrectly
+        // does not return a bool. In this case we expect it to revert
+        // on failure, which was handled above.
+        // If the token does return data, we require that it is a single
+        // value that evaluates to true.
+        assembly {
+            if returndatasize {
+                success := 0
+                if eq(returndatasize, 32) {
+                    // First 64 bytes of memory are reserved scratch space
+                    returndatacopy(0, 0, 32)
+                    success := mload(0)
+                }
+            }
+        }
         require(
             success,
             TRANSFER_FAILED
diff --git a/packages/contracts/src/utils/revert_trace.ts b/packages/contracts/src/utils/revert_trace.ts
new file mode 100644
index 000000000..0bf8384bc
--- /dev/null
+++ b/packages/contracts/src/utils/revert_trace.ts
@@ -0,0 +1,21 @@
+import { devConstants } from '@0xproject/dev-utils';
+import { RevertTraceSubprovider, SolCompilerArtifactAdapter } from '@0xproject/sol-cov';
+import * as _ from 'lodash';
+
+let revertTraceSubprovider: RevertTraceSubprovider;
+
+export const revertTrace = {
+    getRevertTraceSubproviderSingleton(): RevertTraceSubprovider {
+        if (_.isUndefined(revertTraceSubprovider)) {
+            revertTraceSubprovider = revertTrace._getRevertTraceSubprovider();
+        }
+        return revertTraceSubprovider;
+    },
+    _getRevertTraceSubprovider(): RevertTraceSubprovider {
+        const defaultFromAddress = devConstants.TESTRPC_FIRST_ADDRESS;
+        const solCompilerArtifactAdapter = new SolCompilerArtifactAdapter();
+        const isVerbose = true;
+        const subprovider = new RevertTraceSubprovider(solCompilerArtifactAdapter, defaultFromAddress, isVerbose);
+        return subprovider;
+    },
+};
diff --git a/packages/contracts/src/utils/web3_wrapper.ts b/packages/contracts/src/utils/web3_wrapper.ts
index c475d96a9..c9d83a02d 100644
--- a/packages/contracts/src/utils/web3_wrapper.ts
+++ b/packages/contracts/src/utils/web3_wrapper.ts
@@ -2,9 +2,11 @@ import { devConstants, env, EnvVars, web3Factory } from '@0xproject/dev-utils';
 import { prependSubprovider } from '@0xproject/subproviders';
 import { logUtils } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
+import * as _ from 'lodash';
 
 import { coverage } from './coverage';
 import { profiler } from './profiler';
+import { revertTrace } from './revert_trace';
 
 enum ProviderType {
     Ganache = 'ganache',
@@ -48,10 +50,11 @@ const providerConfigs = testProvider === ProviderType.Ganache ? ganacheConfigs :
 export const provider = web3Factory.getRpcProvider(providerConfigs);
 const isCoverageEnabled = env.parseBoolean(EnvVars.SolidityCoverage);
 const isProfilerEnabled = env.parseBoolean(EnvVars.SolidityProfiler);
-if (isCoverageEnabled && isProfilerEnabled) {
-    throw new Error(
-        `Unfortunately for now you can't enable both coverage and profiler at the same time. They both use coverage.json file and there is no way to configure that.`,
-    );
+const isRevertTraceEnabled = env.parseBoolean(EnvVars.SolidityRevertTrace);
+const enabledSubproviderCount = _.filter([isCoverageEnabled, isProfilerEnabled, isRevertTraceEnabled], _.identity)
+    .length;
+if (enabledSubproviderCount > 1) {
+    throw new Error(`Only one of coverage, profiler, or revert trace subproviders can be enabled at a time`);
 }
 if (isCoverageEnabled) {
     const coverageSubprovider = coverage.getCoverageSubproviderSingleton();
@@ -71,5 +74,9 @@ if (isProfilerEnabled) {
     profilerSubprovider.stop();
     prependSubprovider(provider, profilerSubprovider);
 }
+if (isRevertTraceEnabled) {
+    const revertTraceSubprovider = revertTrace.getRevertTraceSubproviderSingleton();
+    prependSubprovider(provider, revertTraceSubprovider);
+}
 
 export const web3Wrapper = new Web3Wrapper(provider);