Add unit tests for various collection-based utility functions

src/utils/arrays.ts

@@ -1,5 +1,5 @@
 /*
-Copyright 2020 The Matrix.org Foundation C.I.C.
+Copyright 2020, 2021 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -15,23 +15,47 @@ limitations under the License.
 */
 
 /**
- * Quickly resample an array to have less data points. This isn't a perfect representation,
- * though this does work best if given a large array to downsample to a much smaller array.
- * @param {number[]} input The input array to downsample.
+ * Quickly resample an array to have less/more data points. If an input which is larger
+ * than the desired size is provided, it will be downsampled. Similarly, if the input
+ * is smaller than the desired size then it will be upsampled.
+ * @param {number[]} input The input array to resample.
  * @param {number} points The number of samples to end up with.
- * @returns {number[]} The downsampled array.
+ * @returns {number[]} The resampled array.
  */
 export function arrayFastResample(input: number[], points: number): number[] {
-    // Heavily inpired by matrix-media-repo (used with permission)
+    if (input.length === points) return input; // short-circuit a complicated call
+
+    // Heavily inspired by matrix-media-repo (used with permission)
     // https://github.com/turt2live/matrix-media-repo/blob/abe72c87d2e29/util/util_audio/fastsample.go#L10
-    const everyNth = Math.round(input.length / points);
-    const samples: number[] = [];
-    for (let i = 0; i < input.length; i += everyNth) {
-        samples.push(input[i]);
+    let samples: number[] = [];
+    if (input.length > points) {
+        // Danger: this loop can cause out of memory conditions if the input is too small.
+        const everyNth = Math.round(input.length / points);
+        for (let i = 0; i < input.length; i += everyNth) {
+            samples.push(input[i]);
+        }
+    } else {
+        // Smaller inputs mean we have to spread the values over the desired length. We
+        // end up overshooting the target length in doing this, so we'll resample down
+        // before returning. This recursion is risky, but mathematically should not go
+        // further than 1 level deep.
+        const spreadFactor = Math.ceil(points / input.length);
+        for (const val of input) {
+            samples.push(...arraySeed(val, spreadFactor));
+        }
+        samples = arrayFastResample(samples, points);
     }
+
+    // Sanity fill, just in case
     while (samples.length < points) {
         samples.push(input[input.length - 1]);
     }
+
+    // Sanity trim, just in case
+    if (samples.length > points) {
+        samples = samples.slice(0, points);
+    }
+
     return samples;
 }
 
@@ -178,6 +202,13 @@ export class GroupedArray<K, T> {
     constructor(private val: Map<K, T[]>) {
     }
 
+    /**
+     * The value of this group, after all applicable alterations.
+     */
+    public get value(): Map<K, T[]> {
+        return this.val;
+    }
+
     /**
      * Orders the grouping into an array using the provided key order.
      * @param keyOrder The key order.

src/utils/enums.ts

@@ -1,5 +1,5 @@
 /*
-Copyright 2020 The Matrix.org Foundation C.I.C.
+Copyright 2020, 2021 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -19,11 +19,23 @@ limitations under the License.
  * @param e The enum.
  * @returns The enum values.
  */
-export function getEnumValues<T>(e: any): T[] {
+export function getEnumValues(e: any): (string | number)[] {
+    // String-based enums will simply be objects ({Key: "value"}), but number-based
+    // enums will instead map themselves twice: in one direction for {Key: 12} and
+    // the reverse for easy lookup, presumably ({12: Key}). In the reverse mapping,
+    // the key is a string, not a number.
+    //
+    // For this reason, we try to determine what kind of enum we're dealing with.
+
     const keys = Object.keys(e);
-    return keys
-        .filter(k => ['string', 'number'].includes(typeof(e[k])))
-        .map(k => e[k]);
+    const values: (string | number)[] = [];
+    for (const key of keys) {
+        const value = e[key];
+        if (Number.isFinite(value) || e[value.toString()] !== Number(key)) {
+            values.push(value);
+        }
+    }
+    return values;
 }
 
 /**

src/utils/objects.ts

@@ -1,5 +1,5 @@
 /*
-Copyright 2020 The Matrix.org Foundation C.I.C.
+Copyright 2020, 2021 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -141,3 +141,21 @@ export function objectKeyChanges<O extends {}>(a: O, b: O): (keyof O)[] {
 export function objectClone<O extends {}>(obj: O): O {
     return JSON.parse(JSON.stringify(obj));
 }
+
+/**
+ * Converts a series of entries to an object.
+ * @param entries The entries to convert.
+ * @returns The converted object.
+ */
+// NOTE: Deprecated once we have Object.fromEntries() support.
+// @ts-ignore - return type is complaining about non-string keys, but we know better
+export function objectFromEntries<K, V>(entries: Iterable<[K, V]>): {[k: K]: V} {
+    const obj: {
+        // @ts-ignore - same as return type
+        [k: K]: V} = {};
+    for (const e of entries) {
+        // @ts-ignore - same as return type
+        obj[e[0]] = e[1];
+    }
+    return obj;
+}

test/Singleflight-test.ts → test/utils/Singleflight-test.ts

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {Singleflight} from "../src/utils/Singleflight";
+import {Singleflight} from "../../src/utils/Singleflight";
 
 describe('Singleflight', () => {
     afterEach(() => {