Function getDeclaration

packages/compiler-cli/src/ngtsc/testing/src/utils.ts:69–90

(
  program: ts.Program,
  fileName: AbsoluteFsPath,
  name: string,
  assert: (value: any) => value is T,
)

 * the `predicate` test.
 */
export function getDeclaration<T extends DeclarationNode>(
  program: ts.Program,
  fileName: AbsoluteFsPath,
  name: string,
  assert: (value: any) => value is T,
): T {
  const sf = getSourceFileOrError(program, fileName);
  const chosenDecls = walkForDeclarations(name, sf);

  if (chosenDecls.length === 0) {
    throw new Error(`No such symbol: ${name} in ${fileName}`);
  }
  const chosenDecl = chosenDecls.find(assert);
  if (chosenDecl === undefined) {
    throw new Error(
      `Symbols with name ${name} in ${fileName} have types: ${chosenDecls.map(
        (decl) => ts.SyntaxKind[decl.kind],
      )}. Expected one to pass predicate "${assert.name}()".`,
    );
  }
  return chosenDecl;
}

/**
 * Walk the AST tree from the `rootNode` looking for a declaration that has the given `name`.