A Symbolic Execution Algorithm for Constraint-Based Testing of Database Programs

In so-called constraint-based testing, symbolic execution is a common technique used as a part of the process to generate test data for imperative programs. Databases are ubiquitous in software and testing of programs manipulating databases is thus essential to enhance the reliability of software. This work proposes and evaluates experimentally a symbolic ex- ecution algorithm for constraint-based testing of database programs. First, we describe SimpleDB, a formal language which offers a minimal and well-defined syntax and seman- tics, to model common interaction scenarios between pro- grams and databases. Secondly, we detail the proposed al- gorithm for symbolic execution of SimpleDB models. This algorithm considers a SimpleDB program as a sequence of operations over a set of relational variables, modeling both the database tables and the program variables. By inte- grating this relational model of the program with classical static symbolic execution, the algorithm can generate a set of path constraints for any finite path to test in the control- flow graph of the program. Solutions of these constraints are test inputs for the program, including an initial content for the database. When the program is executed with respect to these inputs, it is guaranteed to follow the path with re- spect to which the constraints were generated. Finally, the algorithm is evaluated experimentally using representative SimpleDB models.Comment: 12 pages - preliminary wor

Making the Rerum vulgarium fragmenta

The collection of lyric poems that Petrarch worked on for nearly forty years reflects, through successive stages of composition, his evolving poetic and philosophical values. The genesis of the collection, the stratification of its many forms and stages, and its gradually emerging status as Petrarch's crowning achievement have all been studied since the sixteenth century and retraced by many modern scholars, especially after the fundamental reconstruction of the internal history of the text by Ernest Hatch Wilkins and its refinement by Marco Santagata, H. Wayne Storey, and Arnaldo Soldani. In addition to drawing on information from Petrarch's biography and other works, scholars have also made use of the direct testimony of the author, including statements in his letters to Ludwig van Kempen in 1351 (Fam. I.1) and to Pandolfo Malatesta in 1373 (Sen. XIII.11), drafts and marginal notes, and erasures in the final version of the work, which is the basis of what we read today. Petrarch's RVF, along with its contemporary, Boccaccio's Decameron, is the first classical work of Italian literature whose diffusion originates with an autograph; that is, a copy, or rather a series of copies, written in the hand of the author himself. This copy is known as the Vat. Lat. 3195 codex. It is a parchment volume measuring 27 × 20.3 cm, comprising seventy-three pages, and written in semi-gothic script, in part by Petrarch and mainly by his trusted copyist Giovanni Malpaghini, who was in his service from 1364 to April 1367. According to most authorities, the manuscript was completed by Petrarch himself shortly before his death. Besides its philological and linguistic features, it is particularly important due to its status as an “authorial book”; that is to say, Petrarch himself saw to the disposition of the single poems and to the ordering and formatting of the collection. Among the most important paratextual features are the title, “Francisci Petrarche laureati poete Rerum vulgarium fragmenta,” written in Malpaghini's hand in a rubric on f. 1r; the white pages separating the first and the second parts of the collection; and the initial letters of the first sonnet and of canzone 264, “I’ vo’ pensando” (“I go thinking”), painted in red on a golden background with floral ornamentation