Add option to disable spellcheck

Add input-validator and tests

src/input-validator.ts

@@ -24,13 +24,23 @@ export function checkArch(arch: string): void {
 }
 
 export function checkDisableAnimations(disableAnimations: string): void {
-  if (disableAnimations !== 'true' && disableAnimations !== 'false') {
+  if (!isValidBoolean(disableAnimations)) {
     throw new Error(`Input for input.disable-animations should be either 'true' or 'false'.`);
   }
 }
 
+export function checkDisableSpellchecker(disableSpellchecker: string): void {
+  if (!isValidBoolean(disableSpellchecker)) {
+    throw new Error(`Input for input.disable-spellchecker should be either 'true' or 'false'.`);
+  }
+}
+
 export function checkEmulatorBuild(emulatorBuild: string): void {
   if (isNaN(Number(emulatorBuild)) || !Number.isInteger(Number(emulatorBuild))) {
     throw new Error(`Unexpected emulator build: '${emulatorBuild}'.`);
   }
 }
+
+function isValidBoolean(value: string): boolean {
+  return value === 'true' || value === 'false';
+}