• Dates: 3/25.
• Reading: This notes.

Testing Concepts

• testing as an important part of quality assurance
• basic steps:
  • prepare test (test cases + procedure)
  • run program against test and take measurement (trace)
  • determine success vs failure
  • if failure => locate/fix fault => re-test
  • repeat until some stopping criteria met (coverage or reliability)
• basic testing techniques:
  • black box: test external functions
  • white box: test internal implementation
  • coverage-based: cover function/implementation
    specific: control/data/transaction/domain testing
  • usage-based: scenarios and frequencies by users
    list/tree/Markov-chain models
• most applicable to OS/process testing
  transaction flow testing (TFT)

TFT Concepts

• basic concept
  • system level suite of operations
  • abstracted as transaction
  • transactions carried by tokens
  • dynamically serviced by system over time
  • elements of
    CFT (control-flow testing),
    DFT (data-flow testing)
    and beyond
• what is transaction?
  • suite/units of processing
    (typically user oriented)
  • represented in graphs as transaction tokens
  • tokens processed/handled by system
    system services and structure
    routing through the system
    depend on sys. arch. & token type
• examples of transactions:
  • bank transaction/service
  • database transaction/operation
  • processes in operating systems
  • workload in queuing networks
• TFT system = architecture + tokens

TFT: Queuing Testing

• transaction/token handling and queuing
  • multiple tokens to a single link
  • service decisions = queuing discipline
    (scheduling or contention resolution)
  • information carried by tokens:
    time-stamp/history/priority/etc.
• queuing principles at single server:
  • priority: time vs. other:
  • time: FIFO/FCFS, LIFO/stack, etc.
  • other/explicit: SJF, priority#, etc.
  • Pre-emption allowed?
  • (buffer) bounded or unbounded?
  • mixture/combination of queues
  • batch and synchronization

• Testing a single queue
• test case design/selection:
  • conformance to queuing discipline.
  • boundary test: similar to loop test.
  • test cases: input + expected output.
  • combined cases of the above.
• testing specific boundary conditions:
  • bounded queue with bound B
  • lower bound: 0, 1, 2 (always)
  • server busy/idle at lower bound
  • upper bounds: B, B+1, B-1 (bounded Q)
• other test cases:
  • typical case: usage-based testing idea.
  • unbounded Q: capacity testing still needed

• mixed queues: test case combinations
• multiple queues: queuing network testing.

TFT: Synchronization Testing

• Basic synchronization types:
  • merger of two incoming tokens:
    a new outgoing token generated
    similar to DFT in "A = B + C"
    both B and C present to generate A
  • absorption} of one token by another:
    only one incoming token survives
    similar to DFT in "S = S + X"
    both S (orig) and X present
    => S (updated)
• other synchronization possible
• multi-way synchronization:
• N-M synchronization:
  • N-way incoming
  • M-way outgoing
  • treat as multiple N-1 synchronization
  • may involve queuing as well
  • if not possible, ad hoc logic
  • key: relating incoming and outgoing tokens
  • more common in OS synchronization

• Synchronization testing}
  • correct tokens input/produced
  • synchronization of arrivals (timing)
• correct tokens input/produced:
  • input tokens and expected output
  • merger or absorption => output tokens
• synchronization of arrivals (timing):
  • input tokens in different arriving orders
  • example with two way synchronization
  • nothing arrives => no output
  • one arrives => no output
  • two arrive (3 cases: A-B, B-A, AB) => correct token generated
  • combination with correct tokens
• Multi-way synchronization testing:
  • similar: correct token and timing
  • more cases: combinatorial explosion
  • solution: simplify via stages
  • M-N synchronization: earlier discussion
• Multi-stage synchronization:
  • solves combinatorial explosion problem
  • token grouping possibilities
  • in-group synchronization and then cross-group synchronization
  • example: 5-way synchronization
  • shares idea of hierarchical testing

Review for Exam #2

• material covered:
  • deadlocks: Ch 8
  • memory management: Ch. 9
  • virtual memory: Ch. 10
  • OS/process testing: class notes.
• type of questions:
  • multiple choice: all
  • definition/discussion: basic concepts and technique/solution comparisons
  • problem solving: techniques/models/algorithms
    RAG, avoidance/detection algorithms, memory mapping schemes, allocation and replacement algorithms.