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Language model

As explained in Software Testing with Generative AI

A large language model is a machine-learning model trained on extensive text data to generate and transform language from an input prompt.

A large language model (LLM) takes a natural-language prompt and returns a response. Trained on massive datasets, it uses learned statistical weights to predict plausible continuations rather than reasoning like a human. Its value depends on how clearly people frame tasks and evaluate results. section 1.3 section 2.1

LLMs support testing through three related capabilities:

  • Generate test cases, automation code, synthetic data, or other suggested material for a specific task. section 1.1.1 section 3.3.1
  • Transform information between structures, such as test data into SQL, code between languages, or exploratory notes into summaries. section 3.3.2
  • Enhance existing material by reviewing code, adding comments, expanding risk analysis, or suggesting test ideas. section 3.3.3 section 1.1.3

From a vague request to useful test ideas

The prompt “Create tests for a file upload feature” can produce generic checks for valid formats and file-size limits, but it may miss product context. Supplying acceptance criteria—PDF, DOCX, and TXT support; a 20MB limit; progress updates; private initial access; and audit records—gives the LLM a stronger basis for suggestions. A tester must still judge coverage, risks, and correctness. section 3.3.1 section 1.2.2

Figure 1.2 An outline of how tools enhance and extend the reach of testing

Use the area-of-effect model to relate human testing judgment to tools that extend testing reach without replacing its direction. section 1.2.2

LLMs are probabilistic and can hallucinate confidently, so generated code, tests, translations, and recommendations require verification. Prompt engineering improves the chance of useful output by adding context, specifying the task, breaking down complex work, and asking for suitable formats; it does not make results foolproof. section 1.2.3 section 2.4.6 section 2.7

How Software Testing with Generative AI covers it

How deep it goes
Explains prompts, probabilistic prediction, training data, risks, and prompt tactics, but stops short of deep model internals.
Examples
Uses phone keyboard predictions, file-upload test design, code transformation, synthetic data, and Java booking-API code generation.
What it assumes
Assumes testing or development goals, teaches LLM fundamentals from prompt-response behavior and introduces probability-based prediction.
What you can do after
Apply it via prompt engineering to accelerate focused testing work while verifying outputs and retaining human direction.
How it connects
Connects generative AI with machine learning, prompt engineering, software testing, test automation, synthetic data, and hallucination risks.

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