A.F. Mitchell traces the history of the catechism in The Westminster Assembly: Its History and Standards (1884), pp. 408-421; but the text itself has only been published twice: 1) W. Carruthers, The Shorter Catechism of the Westminster Assembly of Divines (1897), pp. 21-26; and 2) Wayne Spear, "The Unfinished Westminster Catechism," in John L. Carson and David W. Hall, To Glorify and Enjoy God: A Commemoration of the 350th Anniversary of the Westminster Assembly (1994), pp. 259-266. The numbering of the questions is inconsistent but there are a total of 55 questions and answers. It begins by teaching that the Scriptures are the only rule of faith and obedience and ends with what is required by the Fourth Commandment.
Although not as polished as the later catechisms produced by the Assembly, this first unfinished catechism is worthy of study, and one is able to see how it helped lay the groundwork for those which followed after, and in which new directions the Assembly decided to go with the later catechisms. One may read the text of the catechism at the link provided above. Below is a sample:
[3. What is the rule of faith and obedience ?]
The only rule of faith and obedience is the written Word of God, contained in the Bible or the Scriptures of the Old and New Testament
[4.] What special proofs are there that the Scriptures of the Old and New Testament are the very Word of God ?
The Scriptures are proved to be the very Word of God by their majesty and holiness of doctrine, and the fulfilling of the prophecies, by their exalting God and debasing man, and yet offering him sufficient means of comfort and salvation, and by their light and power in convincing and converting.
5. Are all these proofs sufficient of themselves to persuade a man to believe that the Scriptures are the Word of God?
It is only the Spirit of God that makes any proofs effectual to assure the soul of this truth, that the Scriptures are the Word of God.