change strongest property type from Array<IntegrityMetadata> to IntegrityMetadataSet

src/index.ts

@@ -241,12 +241,7 @@ export type IntegrityMetadataSetOptions = {
  */
 export class IntegrityMetadataSet {
   #set: ReadonlyArray<IntegrityMetadata>;
-
+  #getPrioritizedHashAlgorithm = getPrioritizedHashAlgorithm;
-  /**
-   * The strongest (most secure) integrity metadata from the set.
-   * @see {@link https://www.w3.org/TR/SRI/#get-the-strongest-metadata-from-set}
-   */
-  readonly strongest: Array<IntegrityMetadata> = [];
 
   /**
    * Create an instance of `IntegrityMetadataSet` from integrity metadata or an array of integrity
@@ -284,40 +279,23 @@ export class IntegrityMetadataSet {
         _getPrioritizedHashAlgorithm = getPrioritizedHashAlgorithm,
     }: IntegrityMetadataSetOptions = {},
   ) {
-    const set: ReadonlyArray<
+    this.#set = [integrity]
-      IntegrityMetadataLike | string | null | undefined
-    > = [integrity]
       .flat()
       .flatMap(
         (
           integrity: IntegrityMetadataLike | string | null | undefined,
-        ): ReadonlyArray<IntegrityMetadataLike | string | null | undefined> =>
+        ): ReadonlyArray<IntegrityMetadataLike | string | null | undefined> => {
-          typeof integrity === "string"
+          if (typeof integrity === "string") {
-            ? integrity.split(SeparatorRegex)
+            return integrity.split(SeparatorRegex);
-            : [integrity],
+          }
-      );
 
-    this.#set = set
+          return [integrity];
+        },
+      )
       .map((integrity) => new IntegrityMetadata(integrity))
       .filter((integrityMetadata) => integrityMetadata.toString() !== "");
 
-    for (const integrityMetadata of this.#set) {
+    this.#getPrioritizedHashAlgorithm = _getPrioritizedHashAlgorithm;
-      const [strongest = new IntegrityMetadata("")] = this.strongest;
-
-      const prioritizedHashAlgorithm = _getPrioritizedHashAlgorithm(
-        strongest.alg as HashAlgorithm,
-        integrityMetadata.alg as HashAlgorithm,
-      );
-
-      switch (prioritizedHashAlgorithm) {
-        case "":
-          this.strongest.push(integrityMetadata);
-          break;
-        case integrityMetadata.alg:
-          this.strongest = [integrityMetadata];
-          break;
-      }
-    }
   }
 
   /**
@@ -330,7 +308,7 @@ export class IntegrityMetadataSet {
    */
   *[Symbol.iterator](): Generator<IntegrityMetadata> {
     for (const integrityMetadata of this.#set) {
-      yield integrityMetadata;
+      yield new IntegrityMetadata(integrityMetadata);
     }
   }
 
@@ -341,11 +319,44 @@ export class IntegrityMetadataSet {
     return this.#set.length;
   }
 
+  /**
+   * The strongest (most secure) integrity metadata from the set.
+   * @see {@link https://www.w3.org/TR/SRI/#get-the-strongest-metadata-from-set}
+   */
+  get strongest(): IntegrityMetadataSet {
+    let strongest = new IntegrityMetadataSet([]);
+
+    for (const integrityMetadata of this.#set) {
+      const [{ alg } = new IntegrityMetadata("")] = strongest;
+
+      const prioritizedHashAlgorithm = this.#getPrioritizedHashAlgorithm(
+        alg as HashAlgorithm,
+        integrityMetadata.alg as HashAlgorithm,
+      );
+
+      switch (prioritizedHashAlgorithm) {
+        case "":
+          strongest = new IntegrityMetadataSet([
+            ...this.strongest,
+            integrityMetadata,
+          ]);
+          break;
+        case integrityMetadata.alg:
+          strongest = new IntegrityMetadataSet(integrityMetadata);
+          break;
+        case alg:
+          break;
+      }
+    }
+
+    return strongest;
+  }
+
   /**
    * Returns an array of the strongest supported hash algorithms in the set.
    */
   get strongestHashAlgorithms(): ReadonlyArray<HashAlgorithm> {
-    const strongestHashAlgorithms = this.strongest
+    const strongestHashAlgorithms = [...this.strongest]
       .map(({ alg }) => alg as HashAlgorithm)
       .filter(Boolean);
 

test/integrity-metadata-set/constructor.ts

@@ -7,11 +7,16 @@ test("supports SHA-256", function () {
     "sha256-MV9b23bQeMQ7isAGTkoBZGErH853yGk0W/yUx1iU7dM=",
   );
 
-  assert.deepEqual(set.strongest[0], {
+  assert.deepEqual(
+    [...set],
+    [
+      {
         alg: "sha256",
         val: "MV9b23bQeMQ7isAGTkoBZGErH853yGk0W/yUx1iU7dM=",
         opt: [],
-  });
+      },
+    ],
+  );
 });
 
 test("supports SHA-384", function () {
@@ -19,11 +24,16 @@ test("supports SHA-384", function () {
     "sha384-VbxVaw0v4Pzlgrpf4Huq//A1ZTY4x6wNVJTCpkwL6hzFczHHwSpFzbyn9MNKCJ7r",
   );
 
-  assert.deepEqual(set.strongest[0], {
+  assert.deepEqual(
+    [...set],
+    [
+      {
         alg: "sha384",
         val: "VbxVaw0v4Pzlgrpf4Huq//A1ZTY4x6wNVJTCpkwL6hzFczHHwSpFzbyn9MNKCJ7r",
         opt: [],
-  });
+      },
+    ],
+  );
 });
 
 test("supports SHA-512", function () {
@@ -31,11 +41,16 @@ test("supports SHA-512", function () {
     "sha512-wVJ82JPBJHc9gRkRlwyP5uhX1t9dySJr2KFgYUwM2WOk3eorlLt9NgIe+dhl1c6ilKgt1JoLsmn1H256V/eUIQ==",
   );
 
-  assert.deepEqual(set.strongest[0], {
+  assert.deepEqual(
+    [...set],
+    [
+      {
         alg: "sha512",
         val: "wVJ82JPBJHc9gRkRlwyP5uhX1t9dySJr2KFgYUwM2WOk3eorlLt9NgIe+dhl1c6ilKgt1JoLsmn1H256V/eUIQ==",
         opt: [],
-  });
+      },
+    ],
+  );
 });
 
 test("accepts options", function () {
@@ -43,11 +58,16 @@ test("accepts options", function () {
     "sha256-MV9b23bQeMQ7isAGTkoBZGErH853yGk0W/yUx1iU7dM=?foo?bar",
   );
 
-  assert.deepEqual(set.strongest[0], {
+  assert.deepEqual(
+    [...set],
+    [
+      {
         alg: "sha256",
         val: "MV9b23bQeMQ7isAGTkoBZGErH853yGk0W/yUx1iU7dM=",
         opt: ["foo", "bar"],
-  });
+      },
+    ],
+  );
 });
 
 test("accepts an IntegrityMetadata like object as input", function () {

test/integrity-metadata-set/strongest.ts

@@ -1,6 +1,6 @@
 import assert from "node:assert";
 import { test } from "node:test";
-import { IntegrityMetadata, IntegrityMetadataSet } from "../../src/index.ts";
+import { IntegrityMetadataSet } from "../../src/index.ts";
 
 test("pick the strongest metadata from set", function () {
   const integrityMetadataSet = new IntegrityMetadataSet(`
@@ -9,11 +9,12 @@ sha384-VbxVaw0v4Pzlgrpf4Huq//A1ZTY4x6wNVJTCpkwL6hzFczHHwSpFzbyn9MNKCJ7r
 sha512-wVJ82JPBJHc9gRkRlwyP5uhX1t9dySJr2KFgYUwM2WOk3eorlLt9NgIe+dhl1c6ilKgt1JoLsmn1H256V/eUIQ==
 `);
 
-  assert.deepEqual(integrityMetadataSet.strongest, [
+  assert.deepEqual(
-    new IntegrityMetadata(
+    integrityMetadataSet.strongest,
+    new IntegrityMetadataSet(
       "sha512-wVJ82JPBJHc9gRkRlwyP5uhX1t9dySJr2KFgYUwM2WOk3eorlLt9NgIe+dhl1c6ilKgt1JoLsmn1H256V/eUIQ==",
     ),
-  ]);
+  );
 });
 
 test("if there are no supported algorithms, return the empty set", function () {
@@ -22,7 +23,10 @@ sha1-lDpwLQbzRZmu4fjajvn3KWAx1pk=
 md5-bNNVbesNpUvKBgtMOUeYOQ==
 `);
 
-  assert.deepEqual(integrityMetadataSet.strongest, []);
+  assert.deepEqual(
+    integrityMetadataSet.strongest,
+    new IntegrityMetadataSet([]),
+  );
 });
 
 test("custom getPrioritizedHashAlgorithm function can be used", function () {
@@ -39,9 +43,10 @@ sha512-wVJ82JPBJHc9gRkRlwyP5uhX1t9dySJr2KFgYUwM2WOk3eorlLt9NgIe+dhl1c6ilKgt1JoLs
     },
   );
 
-  assert.deepEqual(integrityMetadataSet.strongest, [
+  assert.deepEqual(
-    new IntegrityMetadata(
+    integrityMetadataSet.strongest,
+    new IntegrityMetadataSet(
       "sha384-VbxVaw0v4Pzlgrpf4Huq//A1ZTY4x6wNVJTCpkwL6hzFczHHwSpFzbyn9MNKCJ7r",
     ),
-  ]);
+  );
 });