Live Hacking Before (Formal) Unit Testing¶

Initial Structure ¶

$ tree
.
├── bin
│   └── CMakeLists.txt
├── CMakeLists.txt
├── src
│   └── userdb
│       └── CMakeLists.txt
└── tests
    └── CMakeLists.txt

Talk about project plan

In memory UserDB. Features
- Load/store from/to file
- Search
- Iterate

`User`¶

Talk

Database payload
ID is going to be primary key
⟶ UserDB

`UserDB`¶

Create file from scratch (it is the class that we will be talking about)

void insert(const User& u) { /*not caring about duplicates*/ }

`bin/userdb-write-binaryfile.cpp`¶

Talk

End goal: dump db into file format
Start with program bin/userdb-write-binaryfile.cpp

Pull in write-initial
Think about writing
- Commandline parameter ⟶ filename
- How?
- ⟶ db.write(filename);

Extend `UserDB` To Write ¶

In bin/userdb-write-binaryfile.cpp

Add argv[1] ⟶ filename
Add call db.write(filename)

In src/userdb/userdb.{h,cpp}, implement UserDB::write(const string&)

Write a chapter of method documentation!
Loop over std::map entries (using range based for)
Pull in binary-user
open(... O_CREAT|O_TRUNC|O_WRONLY, 0666) (assert’ing that all is well)

Mode 0666!!
Convert User to BinaryUser
- Use htons() from <arpa/inet.h>
- write(), again only assert’ing
Look into written file, using od -c
Complete bin/userdb-write-binaryfile.cpp, to not write hardwired users
- Pull in user-from-stdin
Finally, use bin/userdb-write-binaryfile to enter
- 666, “Joerg”, “Huber”, “joerg@home.com”
- 42, “Caro”, “Huber”, “caro@home.com”
- 7, “Johanna”, “Huber”, “johanna@home.com”

Extend `UserDB` To Read From File, And Iterate ¶

Pull in read-and-dump into bin/userdb-read-binaryfile.cpp
Add to CMakeLists.txt
Implement UserDB::read()
- Pull in read-binary into body of read()
Compile, and see the iteration still not implemented
Pull userdb-iterator into userdb.h
Pull begin-end into userdb.h

Bug: Use “Faschingbauer” As Last Name ¶

Create a new database,
- 666, “Joerg”, “Faschingbauer”, “joerg@home.com”
Dump it. See that email got overwritten.
Write tests/test-funny-overflow.cpp. Suspecting the inmem DB to loose things (foolishly).
- Pull in test-funny-overflow into empty file
- Add to CMakeLists.txt
- Build
- Implement UserDB::find()
- Run
- Works ⟶ next test
Write tests/test-funny-overflow-file.cpp
- Copy tests/test-funny-overflow.cpp to tests/test-funny-overflow-file.cpp
- Pull in temp-file, right inside main()
- Find bug
Discuss: either change everything (errorhandling!)
- ⟶ no, lets just silently truncate
- ⟶ document that as a feature (i.e. modify the test to require “Faschingb”)

Wrap Up: What Do We Have?¶

Code base that works, somehow
How do we know?
⟶ we have two tests

$ for test in ./test-*; do [ -x $test ] && ( $test && echo "SUCCESS: $test" 1>&2 || echo "FAILURE: $test" 1>&2 ) done
SUCCESS: ./test-funny-overflow
SUCCESS: ./test-funny-overflow-file

test-funny-overflow is actually testing UserDB::find()
Rename to test-find