2 files changed, 16 insertions, 0 deletions
diff --git a/packages/assert/src/index.ts b/packages/assert/src/index.ts
index 56f663780..7ad574ec7 100644
--- a/packages/assert/src/index.ts
+++ b/packages/assert/src/index.ts
@@ -12,6 +12,8 @@ export const assert = {
     },
     isValidBaseUnitAmount(variableName: string, value: BigNumber) {
         assert.isBigNumber(variableName, value);
+        const isNegative = value.lessThan(0);
+        this.assert(!isNegative, `${variableName} cannot be a negative number, found value: ${value.toNumber()}`);
         const hasDecimals = value.decimalPlaces() !== 0;
         this.assert(
             !hasDecimals,
diff --git a/packages/assert/test/assert_test.ts b/packages/assert/test/assert_test.ts
index ff337196d..b0fa398d6 100644
--- a/packages/assert/test/assert_test.ts
+++ b/packages/assert/test/assert_test.ts
@@ -22,6 +22,20 @@ describe('Assertions', () => {
             invalidInputs.forEach(input => expect(assert.isBigNumber.bind(assert, variableName, input)).to.throw());
         });
     });
+    describe('#isValidBaseUnitAmount', () => {
+        it('should not throw for valid input', () => {
+            const validInputs = [new BigNumber(23), new BigNumber('45000000')];
+            validInputs.forEach(input =>
+                expect(assert.isValidBaseUnitAmount.bind(assert, variableName, input)).to.not.throw(),
+            );
+        });
+        it('should throw for invalid input', () => {
+            const invalidInputs = [0, undefined, new BigNumber(3.145), 3.145, new BigNumber(-400)];
+            invalidInputs.forEach(input =>
+                expect(assert.isValidBaseUnitAmount.bind(assert, variableName, input)).to.throw(),
+            );
+        });
+    });
     describe('#isString', () => {
         it('should not throw for valid input', () => {
             const validInputs = ['hello', 'goodbye'];