Add more and unify tests for absent object cases

- Unify test data for nonexistence of an object/string and collection.
- Introduce more test through adding missing test data to existing tests.
- Improve logic for checking absence of values to match tests.
- Add missing tests for absent value validation.
- Update documentation to include shared test functionality.

src/application/Context/ApplicationContext.ts

@@ -27,12 +27,12 @@ export class ApplicationContext implements IApplicationContext {
     initialContext: OperatingSystem,
   ) {
     validateApp(app);
-    assertInRange(initialContext, OperatingSystem);
     this.states = initializeStates(app);
     this.changeContext(initialContext);
   }
 
   public changeContext(os: OperatingSystem): void {
+    assertInRange(os, OperatingSystem);
     if (this.currentOs === os) {
       return;
     }
@@ -51,7 +51,7 @@ export class ApplicationContext implements IApplicationContext {
 
 function validateApp(app: IApplication) {
   if (!app) {
-    throw new Error('undefined app');
+    throw new Error('missing app');
   }
 }