refactor: return empty string when decoding CompactBytesArray

ERC725Alliance · Jan 24, 2023 · 5064b0e · 5064b0e
1 parent 7a8a65c
commit 5064b0e
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Showing 2 changed files with 55 additions and 14 deletions.
diff --git a/src/lib/encoder.test.ts b/src/lib/encoder.test.ts
@@ -132,11 +132,6 @@ describe('encoder', () => {
         decodedValue: [`0x${'cafe'.repeat(256)}`, `0x${'beef'.repeat(250)}`],
         encodedValue: `0x0200${'cafe'.repeat(256)}01f4${'beef'.repeat(250)}`,
       },
-      {
-        valueType: 'bytes[CompactBytesArray]',
-        decodedValue: ['0xaabb', '0x', '0x', '0xbeefbeefbeefbeefbeef'],
-        encodedValue: '0x0002aabb00000000000abeefbeefbeefbeefbeef',
-      },
     ];
 
     testCases.forEach((testCase) => {
@@ -154,6 +149,52 @@ describe('encoder', () => {
       });
     });
 
+    describe('when encoding bytes[CompactBytesArray]', () => {
+      it('should encode `0x` elements as `0x0000`', async () => {
+        const testCase = {
+          valueType: 'bytes[CompactBytesArray]',
+          decodedValue: ['0xaabb', '0x', '0x', '0xbeefbeefbeefbeefbeef'],
+          encodedValue: '0x0002aabb00000000000abeefbeefbeefbeefbeef',
+        };
+
+        const encodedValue = encodeValueType(
+          testCase.valueType,
+          testCase.decodedValue,
+        );
+        assert.deepStrictEqual(encodedValue, testCase.encodedValue);
+      });
+
+      it("should encode '' (empty strings) elements as `0x0000`", async () => {
+        const testCase = {
+          valueType: 'bytes[CompactBytesArray]',
+          decodedValue: ['0xaabb', '', '', '0xbeefbeefbeefbeefbeef'],
+          encodedValue: '0x0002aabb00000000000abeefbeefbeefbeefbeef',
+        };
+
+        const encodedValue = encodeValueType(
+          testCase.valueType,
+          testCase.decodedValue,
+        );
+        assert.deepStrictEqual(encodedValue, testCase.encodedValue);
+      });
+    });
+
+    describe('when decoding a bytes[CompactBytesArray] that contains `0000` entries', () => {
+      it("should decode as '' (empty string) in the decoded array", async () => {
+        const testCase = {
+          valueType: 'bytes[CompactBytesArray]',
+          decodedValue: ['0xaabb', '', '', '0xbeefbeefbeefbeefbeef'],
+          encodedValue: '0x0002aabb00000000000abeefbeefbeefbeefbeef',
+        };
+
+        const decodedValue = decodeValueType(
+          testCase.valueType,
+          testCase.encodedValue,
+        );
+        assert.deepStrictEqual(decodedValue, testCase.decodedValue);
+      });
+    });
+
     it('should throw when valueType is unknown', () => {
       assert.throws(
         () => {

diff --git a/src/lib/encoder.ts b/src/lib/encoder.ts
@@ -84,12 +84,6 @@ const decodeDataSourceWithHash = (value: string): URLDataWithHash => {
 const encodeCompactBytesArray = (values: string[]): string => {
   const compactBytesArray = values
     .filter((value, index) => {
-      if (value === '') {
-        throw new Error(
-          `Couldn't encode, value at index ${index} is '', expected '0x'`,
-        );
-      }
-
       if (!isHex(value)) {
         throw new Error(`Couldn't encode, value at index ${index} is not hex`);
       }
@@ -121,9 +115,15 @@ const decodeCompactBytesArray = (compactBytesArray: string): string[] => {
     const length = hexToNumber(
       '0x' + compactBytesArray.slice(pointer, pointer + 4),
     );
-    encodedValues.push(
-      '0x' + compactBytesArray.slice(pointer + 4, pointer + 2 * (length + 2)),
-    );
+
+    if (length === 0) {
+      // empty entries (`0x0000`) in a CompactBytesArray are returned as empty entries in the array
+      encodedValues.push('');
+    } else {
+      encodedValues.push(
+        '0x' + compactBytesArray.slice(pointer + 4, pointer + 2 * (length + 2)),
+      );
+    }
 
     pointer += 2 * (length + 2);
   }