refactor(config): set default module CommonJS after resolving tsconfig (#2280)

Author: ahnpnl

src/config/config-set.spec.ts

@@ -43,8 +43,11 @@ describe('parsedTsConfig', () => {
     expect(get({ tsconfig: { target: 'esnext' } as any }).options.target).toBe(ts.ScriptTarget.ESNext)
   })
 
-  it('should fallback to ES2015 as default target when no target defined in tsconfig', () => {
-    expect(get({ tsconfig: 'tsconfig.spec.json' }).options.target).toBe(ts.ScriptTarget.ES2015)
+  it('should fallback to ES2015 as default target and CommonJS as default module when no target or module defined in tsconfig', () => {
+    const compilerOptions = get({ tsconfig: 'tsconfig.spec.json' }).options
+
+    expect(compilerOptions.target).toBe(ts.ScriptTarget.ES2015)
+    expect(compilerOptions.module).toBe(ts.ModuleKind.CommonJS)
   })
 
   it('should override some options', () => {

src/config/config-set.ts

@@ -447,7 +447,13 @@ export class ConfigSet {
       this.logger.warn(message)
     }
 
-    return result
+    return {
+      ...result,
+      options: {
+        ...result.options,
+        module: result.options.module ?? this.compilerModule.ModuleKind.CommonJS,
+      },
+    }
   }
 
   /**