Refactor to improve iterations

- Use function abstractions (such as map, reduce, filter etc.) over
  for-of loops to gain benefits of having less side effects and easier
  readability.
- Enable `downLevelIterations` for writing modern code with lazy evaluation.
- Refactor for of loops to named abstractions to clearly express their
  intentions without needing to analyse the loop itself.
- Add missing cases for changes that had no tests.

tests/unit/stubs/CategoryCollectionStub.ts

@@ -61,46 +61,27 @@ export class CategoryCollectionStub implements ICategoryCollection {
   }
 
   public getAllScripts(): ReadonlyArray<IScript> {
-    const scripts = [];
-    for (const category of this.actions) {
-      const categoryScripts = getScriptsRecursively(category);
-      scripts.push(...categoryScripts);
-    }
-    return scripts;
+    return this.actions.flatMap((category) => getScriptsRecursively(category));
   }
 
   public getAllCategories(): ReadonlyArray<ICategory> {
-    const categories = [];
-    categories.push(...this.actions);
-    for (const category of this.actions) {
-      const subCategories = getSubCategoriesRecursively(category);
-      categories.push(...subCategories);
-    }
-    return categories;
+    return this.actions.flatMap(
+      (category) => [category, ...getSubCategoriesRecursively(category)],
+    );
   }
 }
 
 function getSubCategoriesRecursively(category: ICategory): ReadonlyArray<ICategory> {
-  const subCategories = [];
-  if (category.subCategories) {
-    for (const subCategory of category.subCategories) {
-      subCategories.push(subCategory);
-      subCategories.push(...getSubCategoriesRecursively(subCategory));
-    }
-  }
-  return subCategories;
+  return (category.subCategories || []).flatMap(
+    (subCategory) => [subCategory, ...getSubCategoriesRecursively(subCategory)],
+  );
 }
 
 function getScriptsRecursively(category: ICategory): ReadonlyArray<IScript> {
-  const categoryScripts = [];
-  if (category.scripts) {
-    categoryScripts.push(...category.scripts);
-  }
-  if (category.subCategories) {
-    for (const subCategory of category.subCategories) {
-      const subCategoryScripts = getScriptsRecursively(subCategory);
-      categoryScripts.push(...subCategoryScripts);
-    }
-  }
-  return categoryScripts;
+  return [
+    ...(category.scripts || []),
+    ...(category.subCategories || []).flatMap(
+      (subCategory) => getScriptsRecursively(subCategory),
+    ),
+  ];
 }

tests/unit/stubs/CategoryStub.ts

@@ -27,10 +27,9 @@ export class CategoryStub extends BaseEntity<number> implements ICategory {
   }
 
   public withScriptIds(...scriptIds: string[]): CategoryStub {
-    for (const scriptId of scriptIds) {
-      this.withScript(new ScriptStub(scriptId));
-    }
-    return this;
+    return this.withScripts(
+      ...scriptIds.map((id) => new ScriptStub(id)),
+    );
   }
 
   public withScripts(...scripts: IScript[]): CategoryStub {

tests/unit/stubs/ExpressionsCompilerStub.ts

@@ -58,12 +58,9 @@ function deepEqual(
   if (!scrambledEqual(expectedParameterNames, actualParameterNames)) {
     return false;
   }
-  for (const parameterName of expectedParameterNames) {
+  return expectedParameterNames.every((parameterName) => {
     const expectedValue = expected.getArgument(parameterName).argumentValue;
     const actualValue = actual.getArgument(parameterName).argumentValue;
-    if (expectedValue !== actualValue) {
-      return false;
-    }
-  }
-  return true;
+    return expectedValue === actualValue;
+  });
 }

tests/unit/stubs/FunctionCallArgumentCollectionStub.ts

@@ -14,9 +14,8 @@ export class FunctionCallArgumentCollectionStub implements IFunctionCallArgument
   }
 
   public withArguments(args: { readonly [index: string]: string }) {
-    for (const parameterName of Object.keys(args)) {
-      const parameterValue = args[parameterName];
-      this.withArgument(parameterName, parameterValue);
+    for (const [name, value] of Object.entries(args)) {
+      this.withArgument(name, value);
     }
     return this;
   }

tests/unit/stubs/ScriptStub.ts

@@ -13,7 +13,7 @@ export class ScriptStub extends BaseEntity<string> implements IScript {
 
   public readonly documentationUrls = new Array<string>();
 
-  public level = RecommendationLevel.Standard;
+  public level? = RecommendationLevel.Standard;
 
   constructor(public readonly id: string) {
     super(id);
@@ -23,7 +23,7 @@ export class ScriptStub extends BaseEntity<string> implements IScript {
     return Boolean(this.code.revert);
   }
 
-  public withLevel(value: RecommendationLevel): ScriptStub {
+  public withLevel(value?: RecommendationLevel): ScriptStub {
     this.level = value;
     return this;
   }