const ts = require('typescript');

const files = {
  'main.ts': 'import "./module";',
  'module.d.ts': 'declare const foo: any;'
};

const host = ts.createCompilerHost({})
const originalReadFile = host.readFile;
host.readFile = (fileName) => files[fileName] || originalReadFile(fileName);

const program = ts.createProgram({ host, rootNames: ['main.ts'], options: { types: [] } });
const typeChecker = program.getDiagnosticsProducingTypeChecker();
const sourceFile = program.getSourceFile('main.ts');

typeChecker.getSymbolAtLocation(sourceFile.statements[0].moduleSpecifier);

console.log(program.getSemanticDiagnostics());