1 files changed, 22 insertions, 19 deletions
diff --git a/packages/assert/src/index.ts b/packages/assert/src/index.ts
index 171909c93..ccf2c9ad8 100644
--- a/packages/assert/src/index.ts
+++ b/packages/assert/src/index.ts
@@ -8,41 +8,41 @@ const HEX_REGEX = /^0x[0-9A-F]*$/i;
 export const assert = {
     isBigNumber(variableName: string, value: BigNumber): void {
         const isBigNumber = _.isObject(value) && (value as any).isBigNumber;
-        this.assert(isBigNumber, this.typeAssertionMessage(variableName, 'BigNumber', value));
+        assert.assert(isBigNumber, assert.typeAssertionMessage(variableName, 'BigNumber', value));
     },
-    isValidBaseUnitAmount(variableName: string, value: BigNumber) {
+    isValidBaseUnitAmount(variableName: string, value: BigNumber): void {
         assert.isBigNumber(variableName, value);
         const isNegative = value.lessThan(0);
-        this.assert(!isNegative, `${variableName} cannot be a negative number, found value: ${value.toNumber()}`);
+        assert.assert(!isNegative, `${variableName} cannot be a negative number, found value: ${value.toNumber()}`);
         const hasDecimals = value.decimalPlaces() !== 0;
-        this.assert(
+        assert.assert(
             !hasDecimals,
             `${variableName} should be in baseUnits (no decimals), found value: ${value.toNumber()}`,
         );
     },
     isString(variableName: string, value: string): void {
-        this.assert(_.isString(value), this.typeAssertionMessage(variableName, 'string', value));
+        assert.assert(_.isString(value), assert.typeAssertionMessage(variableName, 'string', value));
     },
     isFunction(variableName: string, value: any): void {
-        this.assert(_.isFunction(value), this.typeAssertionMessage(variableName, 'function', value));
+        assert.assert(_.isFunction(value), assert.typeAssertionMessage(variableName, 'function', value));
     },
     isHexString(variableName: string, value: string): void {
-        this.assert(
+        assert.assert(
             _.isString(value) && HEX_REGEX.test(value),
-            this.typeAssertionMessage(variableName, 'HexString', value),
+            assert.typeAssertionMessage(variableName, 'HexString', value),
         );
     },
     isETHAddressHex(variableName: string, value: string): void {
-        this.assert(_.isString(value), this.typeAssertionMessage(variableName, 'string', value));
-        this.assert(addressUtils.isAddress(value), this.typeAssertionMessage(variableName, 'ETHAddressHex', value));
+        assert.assert(_.isString(value), assert.typeAssertionMessage(variableName, 'string', value));
+        assert.assert(addressUtils.isAddress(value), assert.typeAssertionMessage(variableName, 'ETHAddressHex', value));
     },
     doesBelongToStringEnum(
         variableName: string,
         value: string,
         stringEnum: any /* There is no base type for every string enum */,
     ): void {
-        const doesBelongToStringEnum = !_.isUndefined(stringEnum[value]);
-        const enumValues = _.keys(stringEnum);
+        const enumValues = _.values(stringEnum);
+        const doesBelongToStringEnum = _.includes(enumValues, value);
         const enumValuesAsStrings = _.map(enumValues, enumValue => `'${enumValue}'`);
         const enumValuesAsString = enumValuesAsStrings.join(', ');
         assert.assert(
@@ -51,19 +51,22 @@ export const assert = {
         );
     },
     hasAtMostOneUniqueValue(value: any[], errMsg: string): void {
-        this.assert(_.uniq(value).length <= 1, errMsg);
+        assert.assert(_.uniq(value).length <= 1, errMsg);
     },
     isNumber(variableName: string, value: number): void {
-        this.assert(_.isFinite(value), this.typeAssertionMessage(variableName, 'number', value));
+        assert.assert(_.isFinite(value), assert.typeAssertionMessage(variableName, 'number', value));
     },
     isBoolean(variableName: string, value: boolean): void {
-        this.assert(_.isBoolean(value), this.typeAssertionMessage(variableName, 'boolean', value));
+        assert.assert(_.isBoolean(value), assert.typeAssertionMessage(variableName, 'boolean', value));
     },
     isWeb3Provider(variableName: string, value: any): void {
         const isWeb3Provider = _.isFunction(value.send) || _.isFunction(value.sendAsync);
-        this.assert(isWeb3Provider, this.typeAssertionMessage(variableName, 'Web3.Provider', value));
+        assert.assert(isWeb3Provider, assert.typeAssertionMessage(variableName, 'Provider', value));
     },
     doesConformToSchema(variableName: string, value: any, schema: Schema, subSchemas?: Schema[]): void {
+        if (_.isUndefined(value)) {
+            throw new Error(`${variableName} can't be undefined`);
+        }
         const schemaValidator = new SchemaValidator();
         if (!_.isUndefined(subSchemas)) {
             _.map(subSchemas, schemaValidator.addSchema.bind(schemaValidator));
@@ -73,15 +76,15 @@ export const assert = {
         const msg = `Expected ${variableName} to conform to schema ${schema.id}
 Encountered: ${JSON.stringify(value, null, '\t')}
 Validation errors: ${validationResult.errors.join(', ')}`;
-        this.assert(!hasValidationErrors, msg);
+        assert.assert(!hasValidationErrors, msg);
     },
     isWebUri(variableName: string, value: any): void {
         const isValidUrl = !_.isUndefined(validUrl.isWebUri(value));
-        this.assert(isValidUrl, this.typeAssertionMessage(variableName, 'web uri', value));
+        assert.assert(isValidUrl, assert.typeAssertionMessage(variableName, 'web uri', value));
     },
     isUri(variableName: string, value: any): void {
         const isValidUri = !_.isUndefined(validUrl.isUri(value));
-        this.assert(isValidUri, this.typeAssertionMessage(variableName, 'uri', value));
+        assert.assert(isValidUri, assert.typeAssertionMessage(variableName, 'uri', value));
     },
     assert(condition: boolean, message: string): void {
         if (!condition) {