feat: add more webhook tests to check for undefined params (#41)

* feat: update webhook's generateSignature undefined checks

* chore: update FormField type link in README

README.md

@@ -112,7 +112,7 @@ the shape
 
 <pre>
 {
-  responses: <a href="https://github.com/opengovsg/formsg-javascript-sdk/blob/master/src/types/index.d.ts#L27">FormField[]</a>
+  responses: <a href="./src/types.ts#L30">FormField</a>[]
   verified?: <a href="https://www.typescriptlang.org/docs/handbook/utility-types.html#recordkt">Record&lt;string, any&gt;</a>
 }
 </pre>

spec/webhooks.spec.ts

@@ -110,6 +110,58 @@ describe('Webhooks', () => {
     ).toThrow(MissingSecretKeyError)
   })
 
+  it('should throw error if generateSignature is called with undefined uri', () => {
+    expect(() =>
+      webhooks.generateSignature({
+        // For TypeScript to accept it since signature only accepts strings, but
+        // still want to test for undefined behavior.
+        uri: undefined!,
+        submissionId,
+        formId,
+        epoch: Date.now(),
+      })
+    ).toThrow(TypeError)
+  })
+
+  it('should throw error if generateSignature is called with undefined submissionId', () => {
+    expect(() =>
+      webhooks.generateSignature({
+        uri,
+        // For TypeScript to accept it since signature only accepts strings, but
+        // still want to test for undefined behavior.
+        submissionId: undefined!,
+        formId,
+        epoch: Date.now(),
+      })
+    ).toThrow(TypeError)
+  })
+
+  it('should throw error if generateSignature is called with undefined formId', () => {
+    expect(() =>
+      webhooks.generateSignature({
+        uri,
+        submissionId,
+        // For TypeScript to accept it since signature only accepts strings, but
+        // still want to test for undefined behavior.
+        formId: undefined!,
+        epoch: Date.now(),
+      })
+    ).toThrow(TypeError)
+  })
+
+  it('should throw error if generateSignature is called with undefined epoch', () => {
+    expect(() =>
+      webhooks.generateSignature({
+        uri,
+        submissionId,
+        formId,
+        // For TypeScript to accept it since signature only accepts strings, but
+        // still want to test for undefined behavior.
+        epoch: undefined!,
+      })
+    ).toThrow(TypeError)
+  })
+
   it('should throw error if constructHeader is called without a secret key in class instantiation', () => {
     const testEpoch = Date.now()
     const validSignature = generateTestSignature(testEpoch)

src/webhooks.ts

@@ -63,6 +63,7 @@ export default class Webhooks {
    * @param params.epoch Number of milliseconds since Jan 1, 1970
    * @returns the generated signature
    * @throws {MissingSecretKeyError} if a secret key is not provided when instantiating this class
+   * @throws {TypeError} if any parameters are undefined
    */
   generateSignature = ({
     uri,
@@ -71,14 +72,18 @@ export default class Webhooks {
     epoch,
   }: {
     uri: string
-    submissionId: Object
+    submissionId: string
     formId: string
     epoch: number
   }) => {
     if (!this.secretKey) {
       throw new MissingSecretKeyError()
     }
 
+    if (!submissionId || !uri || !formId || !epoch) {
+      throw new TypeError('submissionId, uri, formId, or epoch must be provided to generate a webhook signature')
+    }
+
     const baseString = `${
       url.parse(uri).href
     }.${submissionId}.${formId}.${epoch}`