Django Data Model Revisited and Testing Introduction

Transcription

1 Django Data Model Revisited and Testing Introduction CS 370 SE Practicum, Cengiz Günay (Some slides courtesy of Eugene Agichtein and the Internets) CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

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3 Agenda Warm-up project: Late submissions due midnight today, deploy on Dutch Dutch compatibility: Python 2.7 and 3.2 (python3) available Django Ask for optional packages! CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

4 Agenda Warm-up project: Late submissions due midnight today, deploy on Dutch Dutch compatibility: Python 2.7 and 3.2 (python3) available Django Main project: Ask for optional packages! Submit ideas, due Tuesday 2/25 before class CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

5 Agenda Warm-up project: Late submissions due midnight today, deploy on Dutch Dutch compatibility: Python 2.7 and 3.2 (python3) available Django Main project: Upcoming: Ask for optional packages! Submit ideas, due Tuesday 2/25 before class Guest: Student startup LikePlum on Thursday 2/27 CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

6 Agenda Warm-up project: Late submissions due midnight today, deploy on Dutch Dutch compatibility: Python 2.7 and 3.2 (python3) available Django Main project: Upcoming: Today: Ask for optional packages! Submit ideas, due Tuesday 2/25 before class Guest: Student startup LikePlum on Thursday 2/27 Django data manipulation Introduction to testing CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

7 Entry/Exit Surveys Exit survey: Mobile Web & Agile Intro What is a responsive webapp? What principles does it use? Now that you know the pros and cons of using mobile webapps vs. native apps, which one would you prefer? What are the main principles of Agile development? Entry survey: Testing What was the worst bug you encountered/heard about in a program? How do you usually test your code? What was the most advantage you gained by testing? CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

8 Django Data Model Revisited

9 Hypothetical Book database Entities: Author (first_name, last_name, , photo) Book (title, authors, publisher, publication_date) Publisher (name, address, city, state, country, website) Relationships: Author-Book, Book-Publisher Logical design (board) 2/12/2013 CS 370, Spring

10 Better with a diagram? Diamonds indicate aggregation Made with Dia CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

11 Better with a diagram? Diamonds indicate aggregation Made with Dia CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

12 Better with a diagram? Diamonds indicate aggregation Made with Dia CS 370, Günay (Emory) Django Data and Testing Intro Spring / 8

13 Django Implementation class Publisher(models.Model): name = models.charfield(maxlength=30) website = models.urlfield() #implicit: ID (primary key) class Author(models.Model): first_name = models.charfield(maxlength=30) last_name = models.charfield(maxlength=40) = models. field() headshot = models.imagefield(upload_to='/tmp') class Book(models.Model): title = models.charfield(maxlength=100) authors = models.manytomanyfield(author) publisher = models.foreignkey(publisher) publication_date = models.datefield() 2/12/2013 CS 370, Spring

14 Important Notes Table names are automatically generated by combining the name of the app (books) and the lowercase name of the model (publisher, book, and author). You can override this behavior. Django adds a primary key for each table automatically the id fields. By convention, Django appends "_id" to the foreign key field name. The foreign key relationship is made explicit by a REFERENCES statement publisher = models.foreignkey(publisher) 2/12/2013 CS 370, Spring

15 Basic Data Access (API) from books.models import Publisher p1 = Publisher(name='Addison-Wesley', address='75 Arlington Street',... city='boston', state_province='ma', country='u.s.a.',... website=' p1.save() To retrieve objects from the database, use the attribute Publisher.objects publisher_list = Publisher.objects.all() 2/12/2013 CS 370, Spring

16 ToString() Add str () method to our Publisher object class Publisher(models.Model): def str (self): return self.name 2/12/2013 CS 370, Spring

17 Selecting objects Publisher.objects.filter(name="Apress Publishing") SELECT id, name, address, city, state_province, country, website FROM book_publisher WHERE name = 'Apress Publishing'; Publisher.objects.filter(name contains="press") Publisher.objects.get(name="Apress Publishing") Can cause exceptions, use Try/Except 2/12/2013 CS 370, Spring

18 Deleting objects p = Publisher.objects.get(name="Addison-Wesley") p.delete() Deletions are permanent, so be careful! avoid deleting objects unless you absolutely have to relational databases don t do undo so well, and restoring from backups is painful. It s often a good idea to add active flags to your data models. You can look up only active objects, and simply set the active field to False instead of deleting the object. 2/12/2013 CS 370, Spring

19 Metadata Django uses internal class Meta as a place to specify additional metadata about a model. It s completely optional, but it can do some very useful things. class Publisher(models.Model):. class Meta: ordering = ["name"] 2/12/2013 CS 370, Spring

20 Making Changes to a Database Schema If you add or change a model s field, or if you delete a model, you ll need to make the change in your database manually. Django will complain if a model contains a field that has not yet been created in the database table. This will cause an error the first time you use the Django database API to query the given table (i.e., it will happen at code execution time, not at compilation time). Django does not care if a database table contains columns that are not defined in the model. Django does not care if a database contains a table that is not represented by a model. 2/12/2013 CS 370, Spring

21 Making Changes to Database Schema (2) 2/12/2013 CS 370, Spring

22 Django book: Onwards and upwords Common mistakes/gotchas: 2/12/2013 CS 370, Spring

23 Introduction to Testing

24 Agile Dev: Test Early and Often "Code without tests is broken by design. J. Kaplan-Moss Providing automated tests for your code is a way to repeatedly ensure that the code you wrote works as advertised. When you first get started, writing tests sounds like extra work. But simple tests are easy to write and having some tests is better than no tests at all. 2/12/2013 CS 370, Spring

25 Testing: The First Bugs Hopper s bug (moth stuck in a relay on an early machine) It has been just so in all of my inventions. The first step is an intuition, and comes with a burst, then difficulties arise this thing gives out and [it is] then that 'Bugs' as such little faults and difficulties are called show themselves and months of intense watching, study and labor are requisite... Thomas Edison Ammann & Offutt 14

26 Costly Software Failures NIST report, The Economic Impacts of Inadequate Infrastructure for Software Testing (2002) Inadequate software testing costs the US alone between $22 and $59 billion annually Better approaches could cut this amount in half Huge losses due to web application failures Financial services : $6.5 million per hour (just in USA!) Credit card sales applications : $2.4 million per hour (in USA) In Dec 2006, Amazon.com s BOGO offer turned into a double discount 2007 : Symantec says that most security vulnerabilities are due to faulty software Ammann & Offutt 15

27 Spectacular Software Failures NASA s Mars lander: September 1999, crashed due to a units integration fault Mars Polar Lander crash site? Toyota brakes : Dozens dead, thousands of crashes Major failures: Ariane 5 explosion, Mars Polar Lander, Intel s Pentium FDIV bug Poor testing of safety-critical software can cost lives : THERAC-25 radiation machine: 3 dead Ariane 5: exception-handling bug : forced self destruct on maiden flight (64-bit to 16-bit conversion: about 370 million $ lost) THERAC-25 design Ammann & Offutt 16

28 Software is a Skin that Surrounds Our Civilization Introduction to Software Testing (Ch 1) Quote due to Dr. Mark Harman Ammann & Offutt 17

29 Airbus 319 Safety Critical Software Control Loss of autopilot Loss of most flight deck lighting and intercom Loss of both the commander s and the co-pilot s primary flight and navigation displays! Ammann & Offutt 18

30 Northeast Blackout of generating units and 256 power plants shut down Affected 10 million people in Ontario, Canada Affected 40 million people in 8 US states Financial losses of $6 Billion USD The alarm system in the energy management system failed due to a software error and operators were not informed of the power overload in the system Ammann & Offutt 19

31 Test Design in Context Test Design is the process of designing input values that will effectively test software Test design is one of several activities for testing software Most mathematical Most technically challenging Ammann & Offutt 20

32 Types of Test Activities Testing can be broken up into four general types of activities 1. Test Design 1.a) Criteria-based 2. Test Automation 1.b) Human-based 3. Test Execution 4. Test Evaluation Each type of activity requires different skills, background knowledge, education and training Ammann & Offutt 21

33 1. Test Design (a) Criteria-Based This is the most technical job in software testing Requires knowledge of : Discrete math Programming Testing This is intellectually stimulating, rewarding, and challenging Test design is analogous to software architecture on the development side Ammann & Offutt 22

34 2. Test Automation Fairly straightforward programming small pieces and simple algorithms Requires very little theory Who is responsible for determining and embedding the expected outputs? Test designers may not always know the expected outputs Test evaluators need to get involved early to help with this Ammann & Offutt 23

35 3. Test Execution This is easy and trivial if the tests are automated Requires basic computer skills Interns Employees with no technical background If, for example, GUI tests are not well automated, this requires a lot of manual labor Ammann & Offutt 24

36 Types of Test Activities Summary These four general test activities are quite different 1a. Design Design test values to satisfy engineering goals It is a poor use of resources to use people Criteria inappropriately Requires knowledge of discrete math, programming and testing 1b. Design Design test values from domain knowledge and intuition Human 2. Automatio n Requires knowledge of domain, UI, testing Embed test values into executable scripts Requires knowledge of scripting 3. Execution Run tests on the software and record the results Requires very little knowledge 4. Evaluation Evaluate results of testing, report to developers Requires domain knowledge Ammann & Offutt 25

37 Common Types of Testing Unit tests cover very small, highly-specific areas of code. There's usually relatively few interactions with other areas of the software. useful for critical components Integration tests cover multiple different facets of the application working together to produce a result. ensure that data flow is right handle multiple user interactions. 2/12/2013 CS 370, Spring

38 What is Unit Testing? unittest: testing framework used to write and run repeatable automated tests A structure for writing test drivers unittest features include: Assertions for testing expected results Test features for sharing common test data Test suites for easily organizing and running tests Graphical and textual test runners Junit (equivalent for Java) is widely used in industry Ammann & Offutt 27

39 Unit Tests (cont d) Can be used to test an entire object part of an object a method or some interacting methods interaction between several objects It is primarily for unit and integration testing, not system testing Each test is embedded into one test method A test class contains one or more test methods Test classes include : A test runner to run the tests (main()) A collection of test methods Methods to set up the state before and update the state after each test and before and after all tests Ammann & Offutt 28

40 Software Testing in Django References: ng/?from=olddocs Unit tests Fixtures Practical examples 2/12/2013 CS 370, Spring

41 What To Test? If your model has custom methods, you should test that, usually with unit tests. Custom views, forms, template tags, context processors 2/12/2013 CS 370, Spring

42 When to Test? Test-first is where you write the necessary tests to demonstrate proper behavior of the code BEFORE you write the code to solve the problem at hand. Test-after is when you've already written the code to solve the problem, then you go back & create tests to make sure the behavior of the code you wrote is correct. 2/12/2013 CS 370, Spring

43 Basic Unit Testing in Django (Tutorial) /12/2013 CS 370, Spring

44 Next Class: User stories, use cases, scenarios, UI design (online make-up class)