226: support for array-shaped payloads

README-INPUT-OUTPUT.md

@@ -10,7 +10,7 @@ The state machine accepts the following input parameters:
 * **lambdaARN** (required, string): unique identifier of the Lambda function you want to optimize
 * **powerValues** (optional, string or list of integers): the list of power values to be tested; if not provided, the default values configured at deploy-time are used (by default: 128MB, 256MB, 512MB, 1024MB, 1536MB, and 3008MB); you can provide any power values between 128MB and 10,240MB (⚠️ [New AWS accounts have reduced concurrency and memory quotas, 3008MB max](https://docs.aws.amazon.com/lambda/latest/dg/gettingstarted-limits.html))
 * **num** (required, integer): the # of invocations for each power configuration (minimum 5, recommended: between 10 and 100)
-* **payload** (string, object, or list): the static payload that will be used for every invocation (object or string); when using a list, a weighted payload is expected in the shape of `[{"payload": {...}, "weight": X }, {"payload": {...}, "weight": Y }, {"payload": {...}, "weight": Z }]`, where the weights `X`, `Y`, and `Z` are treated as relative weights (not percentages); more details below in the [Weighted Payloads section](#user-content-weighted-payloads)
+* **payload** (string, object, or list): the static payload that will be used for every invocation (object or string); when using a list the payload will be treated as a weighted payload if and only if it's in the shape of `[{"payload": {...}, "weight": X }, {"payload": {...}, "weight": Y }, {"payload": {...}, "weight": Z }]`, where the weights `X`, `Y`, and `Z` are treated as relative weights (not percentages); more details below in the [Weighted Payloads section](#user-content-weighted-payloads)
 * **payloadS3** (string): a reference to Amazon S3 for large payloads (>256KB), formatted as `s3://bucket/key`; it requires read-only IAM permissions, see `payloadS3Bucket` and `payloadS3Key` below and find more details in the [S3 payloads section](#user-content-s3-payloads)
 * **parallelInvocation** (false by default): if true, all the invocations will be executed in parallel (note: depending on the value of `num`, you may experience throttling when setting `parallelInvocation` to true)
 * **strategy** (string): it can be `"cost"` or `"speed"` or `"balanced"` (the default value is `"cost"`); if you use `"cost"` the state machine will suggest the cheapest option (disregarding its performance), while if you use `"speed"` the state machine will suggest the fastest option (disregarding its cost). When using `"balanced"` the state machine will choose a compromise between `"cost"` and `"speed"` according to the parameter `"balancedWeight"`
@@ -65,6 +65,9 @@ You can use different alias names such as `dev`, `test`, `production`, etc. If y
 
 ### Weighted Payloads
 
+> [!IMPORTANT]
+> Your payload will only be treated as a weighted payload if it adheres to the JSON structure that follows. Otherwise, it's assumed to be an array-shaped payload.
+
 Weighted payloads can be used in scenarios where the payload structure and the corresponding performance/speed could vary a lot in production and you'd like to include multiple payloads in the tuning process.
 
 You may want to use weighted payloads also in case of functions with side effects that would be hard or impossible to test with the very same payload (for example, a function that deletes records from a database).

lambda/utils.js

@@ -383,13 +383,8 @@ module.exports._fetchS3Object = async(bucket, key) => {
  * Generate a list of `num` payloads (repeated or weighted)
  */
 module.exports.generatePayloads = (num, payloadInput) => {
-    if (Array.isArray(payloadInput)) {
-        // if array, generate a list of payloads based on weights
-
-        // fail if empty list or missing weight/payload
-        if (payloadInput.length === 0 || payloadInput.some(p => !p.weight || !p.payload)) {
-            throw new Error('Invalid weighted payload structure');
-        }
+    if (utils.isWeightedPayload(payloadInput)) {
+        // if weighted array, generate a list of payloads based on weights
 
         if (num < payloadInput.length) {
             throw new Error(`You have ${payloadInput.length} payloads and only "num"=${num}. Please increase "num".`);
@@ -429,6 +424,17 @@ module.exports.generatePayloads = (num, payloadInput) => {
     }
 };
 
+/**
+ * Check if payload is an array where each element contains the property "weight"
+ */
+module.exports.isWeightedPayload = (payload) => {
+    /**
+     * Return true only if the input is a non-empty array where the elements contain a weight property.
+     * e.g. [{ "payload": {...}, "weight": 5 }, ...]
+     */
+    return Array.isArray(payload) && payload.every(p => p.weight && p.payload) && !!payload.length;
+};
+
 /**
  * Convert payload to string, if it's not a string already
  */

test/unit/test-utils.js

@@ -37,7 +37,7 @@ lambdaMock.on(DeleteFunctionCommand).resolves({});
 lambdaMock.on(CreateAliasCommand).resolves({});
 lambdaMock.on(DeleteAliasCommand).resolves({});
 lambdaMock.on(InvokeCommand).resolves({});
-lambdaMock.on(UpdateAliasCommand).resolves({})
+lambdaMock.on(UpdateAliasCommand).resolves({});
 const s3Mock = awsV3Mock.mockClient(S3Client);
 s3Mock.reset();
 s3Mock.on(GetObjectCommand).resolves({
@@ -611,12 +611,22 @@ describe('Lambda Utils', () => {
             });
         });
 
-        it('should explode if invalid weighted payloads', async () => {
-            expect(() => utils.generatePayloads(10, [])).to.throwError();
-            expect(() => utils.generatePayloads(10, [{}])).to.throwError();
-            expect(() => utils.generatePayloads(10, [1, 2, 3])).to.throwError();
-            expect(() => utils.generatePayloads(10, [{ weight: 1 }])).to.throwError();
-            expect(() => utils.generatePayloads(10, [{ payload: {} }])).to.throwError();
+        it('should return input array as output if not weighted', async() => {
+            let payloads = [
+                [],
+                [{}],
+                [1, 2, 3],
+                [{ weight: 1 }],
+                [{ payload: {}, weight: 1 }, { payload: {}}],
+                [{ payload: {} }],
+            ];
+
+            payloads.forEach(payload => {
+                let output = utils.generatePayloads(10, payload);
+
+                expect(output.length).to.be(10);
+                expect(output.every(p => p === JSON.stringify(payload))).to.be(true);
+            });
         });
 
         it('should explode if num < count(payloads)', async () => {
@@ -826,6 +836,55 @@ describe('Lambda Utils', () => {
 
     });
 
+    describe('isWeightedPayload', () => {
+        it('should return true for a correctly weighted payload', () => {
+            const validPayload = [
+                { payload: { data: 'foo' }, weight: 5 },
+                { payload: { data: 'bar' }, weight: 10 },
+            ];
+            expect(utils.isWeightedPayload(validPayload)).to.be(true);
+        });
+
+        it('should return false for payload only containing weights (no "payload" property)', () => {
+            const validPayload = [
+                { weight: 5 },
+                { weight: 10 },
+            ];
+            expect(utils.isWeightedPayload(validPayload)).to.be(false);
+        });
+
+        it('should return false for a payload that is not an array', () => {
+            const invalidPayload = { payload: { data: 'foo' }, weight: 5 };
+            expect(utils.isWeightedPayload(invalidPayload)).to.be(false);
+        });
+
+        it('should return false for an undefined payload', () => {
+            const invalidPayload = undefined;
+            expect(utils.isWeightedPayload(invalidPayload)).to.be(false);
+        });
+
+        it('should return false for an empty array payload', () => {
+            const invalidPayload = [];
+            expect(utils.isWeightedPayload(invalidPayload)).to.be(false);
+        });
+
+        it('should return false for an invalid payload array (elements missing weight property)', () => {
+            const invalidPayload = [
+                { payload: { data: 'foo' } },
+                { payload: { data: 'bar' }, weight: 10 },
+            ];
+            expect(utils.isWeightedPayload(invalidPayload)).to.be(false);
+        });
+
+        it('should return false for an invalid payload (elements missing payload property)', () => {
+            const invalidPayload = [
+                { weight: 5 },
+                { payload: { data: 'bar' }, weight: 10 },
+            ];
+            expect(utils.isWeightedPayload(invalidPayload)).to.be(false);
+        });
+    });
+
     describe('fetchPayloadFromS3', () => {
 
         it('should fetch the object from S3 if valid URI', async () => {