The Testament of Job was composed in Greek. A fragmentary fourth-century Coptic manuscript is our earliest witness to it. We have published a translation by Gesa Schenke ("The Testament of Job: Coptic Fragments") in Old Testament Pseudepigrapha: More Noncanonical Scriptures (Ed. Bauckham, Davila, and Panayotov; Eerdmans, 2013), pp. 160-175. So you should buy this book.
For Phil Long's blog series on the Old Testament Pseudepigrapha start here and follow the links. He is currently working through the Testaments and he just finished the Testaments of the Twelve Patriarchs. Cross-file under Old Testament Pseudepigrapha Watch.
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