fix: caching: resetting global static variable for each run, fixed actual setting of caching true/false (#238)

Author: gethrok

expression-src/main/src/interpreter/EnvironmentCache.cls

@@ -10,12 +10,16 @@ public with sharing class EnvironmentCache {
         isStandardFunctionCacheDisabled = true;
     }
 
+    public static void enableCache() {
+        isStandardFunctionCacheDisabled = false;
+    }
+
     public static void cacheStandardFunctionCall(
         Environment env,
         Expr.FunctionCall function,
         Object result
     ) {
-        cacheFunctionCall(isStandardFunctionCacheDisabled, env, function, result);
+        cacheFunctionCall(!isStandardFunctionCacheDisabled, env, function, result);
     }
 
     public static void cacheCustomMetadataFunctionCall(

expression-src/main/src/interpreter/tests/EvaluatorCustomContextCacheTest.cls

@@ -0,0 +1,35 @@
+@IsTest
+private class EvaluatorCustomContextCacheTest {
+
+    @IsTest
+    static void standardFunctionCacheDisabled_doesNotReuseFirstCustomContext() {
+        Configuration config1 = new Configuration();
+        config1.cacheStandardFunctionResults = false;
+        config1.customContext = new Map<String, Object>{
+                'value' => 'first'
+        };
+
+        Configuration config2 = new Configuration();
+        config2.cacheStandardFunctionResults = false;
+        config2.customContext = new Map<String, Object>{
+                'value' => 'second'
+        };
+
+        Test.startTest();
+        Object firstResult = Evaluator.run('UPPER(@value)', config1);
+        Object secondResult = Evaluator.run('UPPER(@value)', config2);
+        Test.stopTest();
+
+        System.assertEquals(
+                'FIRST',
+                firstResult,
+                'First evaluation must use the first customContext, not cached result from first run.'
+        );
+        System.assertEquals(
+                'SECOND',
+                secondResult,
+                'Second evaluation must use the second customContext, not cached result from first run.'
+        );
+    }
+
+}

expression-src/main/src/interpreter/tests/EvaluatorCustomContextCacheTest.cls-meta.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
+    <apiVersion>65.0</apiVersion>
+    <status>Active</status>
+</ApexClass>

expression-src/main/src/resolver/EvaluatorResolver.cls

@@ -87,7 +87,9 @@ public with sharing abstract class EvaluatorResolver {
         eventNotifier.notify(new OnEvaluationStartEvent(config));
 
         // Disable cache if disabled in the congif
-        if (!config.cacheStandardFunctionResults) {
+        if (config.cacheStandardFunctionResults) {
+            EnvironmentCache.enableCache();
+        } else {
             EnvironmentCache.disableCache();
         }