Add more complex test case for readArray; minor code cleanup

Author: robertwayne

typescript/src/bufferfish.test.ts

@@ -459,3 +459,40 @@ test("should return error for arrays exceeding maximum length", () => {
         Error("array length 65536 exceeds maximum size of 65535"),
     )
 })
+
+test("should read an array of objects implementing read methods", () => {
+    const arr = [
+        { id: 1, name: "Alice", key: { inner: 1 } },
+        { id: 2, name: "Bob", key: { inner: 2 } },
+        { id: 3, name: "Charlie", key: { inner: 3 } },
+    ]
+
+    const decodeKey = (bf: Bufferfish) => {
+        const inner = bf.readUint8()
+        if (inner instanceof Error) {
+            throw inner
+        }
+        return { inner }
+    }
+
+    const decodePerson = (bf: Bufferfish) => {
+        const id = bf.readUint8()
+        const name = bf.readString()
+        const key = decodeKey(bf)
+        if (id instanceof Error || name instanceof Error) {
+            throw id instanceof Error ? id : name
+        }
+        return { id, name, key }
+    }
+
+    const bf = new Bufferfish()
+
+    bf.writeArray(arr, (person) => {
+        bf.writeUint8(person.id)
+        bf.writeString(person.name)
+        bf.writeUint8(person.key.inner)
+    })
+
+    const people = bf.readArray(() => decodePerson(bf))
+    expect(people).toEqual(arr)
+})

typescript/src/bufferfish.ts

@@ -583,23 +583,26 @@ export class Bufferfish {
     /**
      * Attempts to read a variable-length array of elements from the buffer.
      */
-    public readArray<T>(readFn: () => T): Array<T> | Error {
+    public readArray<T>(readFn: () => T | Error): Array<T> | Error {
         const lengthOrError = this.readUint16()
         if (lengthOrError instanceof Error) {
             return lengthOrError
         }
 
-        const length = lengthOrError as number
-        const values: Array<T> = []
-        for (let i = 0; i < length; i++) {
-            const valueOrError = readFn()
-            if (valueOrError instanceof Error) {
-                return valueOrError
-            }
+        const length = lengthOrError
+        const values: Array<T> = new Array(length)
 
-            values.push(valueOrError as T)
+        try {
+            for (let i = 0; i < length; i++) {
+                const valueOrError = readFn()
+                if (valueOrError instanceof Error) {
+                    return valueOrError
+                }
+                values[i] = valueOrError as T
+            }
+            return values
+        } catch (error) {
+            return error instanceof Error ? error : new Error(String(error))
         }
-
-        return values
     }
 }