feat: Allow variable nesting (#294)

Author: doosuu

src/modules/variables.ts

@@ -162,9 +162,16 @@ export class VariableCollection {
     }
 
     substitute(str: string): string {
-        for (const kv of this._variables.entries()) {
-            str = str.replaceAll(`\$\{\{ ${kv[0]} \}\}`, kv[1]);
+        // Number of variable nestings allowed.
+        // E.g. a variable can include a reference to another variable value
+        const ALLOWED_VARIABLE_REFERENCE_LEVELS = 1;
+
+        for (let i = 0; i <= ALLOWED_VARIABLE_REFERENCE_LEVELS; ++i) {
+            for (const kv of this._variables.entries()) {
+                str = str.replaceAll(`\$\{\{ ${kv[0]} \}\}`, kv[1]);
+            }
         }
+
         return str;
     }
 

test/unit/variables.test.ts

@@ -86,6 +86,18 @@ describe('variables - module', () => {
                     description: 'A bool with a default value',
                     default: false,
                 },
+                {
+                    name: 'testLevelTwoNesting',
+                    type: 'string',
+                    description: 'A variable with a variable reference',
+                    default: 'I am unable to hold another level of reference ${{ testWithDefault }}',
+                },
+                {
+                    name: 'testVariableReference',
+                    type: 'string',
+                    description: 'A variable with a variable reference',
+                    default: 'I reference the value of ${{ testNumber }} and ${{ testLevelTwoNesting }}',
+                },
             ],
         };
         pkg2Comp1Manifest = {
@@ -241,6 +253,12 @@ describe('variables - module', () => {
             expect(envVars['builtin_package_github_ref']).to.equal('v1.1.1');
             expect(envVars['builtin_component_id']).to.equal('test-component');
         });
+        it('should allow one level of variable references', () => {
+            const vars = VariableCollection.build([componentContext], variablesMapProjCfg, componentContext);
+            expect(vars.substitute('${{ testVariableReference }}')).to.equal(
+                'I reference the value of 1 and I am unable to hold another level of reference ${{ testWithDefault }}',
+            );
+        });
         it('should not throw an error when trying to build VariableCollection with identical VariableDefinition names', () => {
             const buildVariableCollection = () => {
                 const alreadyExistingVariableDefName = {