fix: VTL string escaping

$util.escapeJavaScript() escapes the characters in a string using
JavaScript string rules. This function will turn any regular single
quotes (') into escaped ones (\'). However, the escaped single quotes
are not valid in JSON. Thus, when the output from this function is used
in a JSON property, you must turn any escaped single quotes (\') back to
regular single quotes (').

Author: thibaultdalban

lib/deploy/events/apiGateway/methods.js

@@ -288,7 +288,7 @@ module.exports = {
     return {
       'Fn::Sub': [
         `
-#set( $body = $util.escapeJavaScript($input.json('$')).replaceAll(\"\\\\'\", \"'\") )
+#set( $body = $util.escapeJavaScript($input.json('$')).replaceAll("\\\\'", "'") )
 {"input": "$body", "name": "$context.requestId", "stateMachineArn":"\${StateMachineArn}"}`,
         { StateMachineArn: { Ref: stateMachineLogicalId } },
       ],

lib/deploy/events/apiGateway/methods.test.js

@@ -265,6 +265,25 @@ describe('#methods()', () => {
     });
   });
 
+  describe('#buildDefaultRequestTemplate()', () => {
+    it('should return the default request template', () => {
+      const defaultRequestTemplate = serverlessStepFunctions
+        .buildDefaultRequestTemplate('StateMachineStepFunctionsStateMachine');
+      expect(defaultRequestTemplate['Fn::Sub'][0])
+        .to.contain(
+          '#set( $body = $util.escapeJavaScript($input.json(\'$\')).replaceAll("\\\\\'", "\'") )',
+        );
+      expect(defaultRequestTemplate['Fn::Sub'][0])
+        .to.contain(
+          '{"input": "$body", "name": "$context.requestId", "stateMachineArn":"${StateMachineArn}"}',
+        );
+      expect(defaultRequestTemplate['Fn::Sub'][1])
+        .to.be.deep.equal({
+          StateMachineArn: { Ref: 'StateMachineStepFunctionsStateMachine' },
+        });
+    });
+  });
+
   describe('#getMethodResponses()', () => {
     it('should return a corresponding methodResponses resource', () => {
       expect(serverlessStepFunctions.getMethodResponses().Properties)