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Best AI model for Unit Test Generation (2026)
Generating thorough test suites for existing functions. Ranked from 346 live models on the OpenRouter catalog, weighted for reasoning quality, structured output, context window.
| # | Model | Score | In / 1M | Out / 1M | Context | |
|---|---|---|---|---|---|---|
| 1 | Qwen: Qwen3.6 Plusqwen/qwen3.6-plus | 124 | $0.33 | $1.95 | 1,000,000 | Try → |
| 2 | xAI: Grok 4.20x-ai/grok-4.20 | 124 | $2.00 | $6.00 | 2,000,000 | Try → |
| 3 | OpenAI: GPT-5.4 Nanoopenai/gpt-5.4-nano | 124 | $0.20 | $1.25 | 400,000 | Try → |
| 4 | OpenAI: GPT-5.4 Miniopenai/gpt-5.4-mini | 124 | $0.75 | $4.50 | 400,000 | Try → |
| 5 | OpenAI: GPT-5.4openai/gpt-5.4 | 124 | $2.50 | $15.00 | 1,050,000 | Try → |
| 6 | Google: Gemini 3.1 Flash Lite Previewgoogle/gemini-3.1-flash-lite-preview | 124 | $0.25 | $1.50 | 1,048,576 | Try → |
| 7 | Qwen: Qwen3.5-Flashqwen/qwen3.5-flash-02-23 | 124 | $0.07 | $0.26 | 1,000,000 | Try → |
| 8 | Google: Gemini 3.1 Pro Preview Custom Toolsgoogle/gemini-3.1-pro-preview-customtools | 124 | $2.00 | $12.00 | 1,048,576 | Try → |
| 9 | OpenAI: GPT-5.3-Codexopenai/gpt-5.3-codex | 124 | $1.75 | $14.00 | 400,000 | Try → |
| 10 | Google: Gemini 3.1 Pro Previewgoogle/gemini-3.1-pro-preview | 124 | $2.00 | $12.00 | 1,048,576 | Try → |
| 11 | Qwen: Qwen3.5 Plus 2026-02-15qwen/qwen3.5-plus-02-15 | 124 | $0.26 | $1.56 | 1,000,000 | Try → |
| 12 | Google: Gemini 3 Flash Previewgoogle/gemini-3-flash-preview | 124 | $0.50 | $3.00 | 1,048,576 | Try → |
| 13 | OpenAI: GPT-5.2openai/gpt-5.2 | 124 | $1.75 | $14.00 | 400,000 | Try → |
| 14 | xAI: Grok 4.1 Fastx-ai/grok-4.1-fast | 124 | $0.20 | $0.50 | 2,000,000 | Try → |
| 15 | OpenAI: GPT-5.1openai/gpt-5.1 | 124 | $1.25 | $10.00 | 400,000 | Try → |
How we ranked these
For Unit Test Generation, we weight models on reasoning quality, structured output, context window. Higher means better. Scores combine OpenRouter's model metadata (context length, modality support, tool calling, structured output, reasoning capability) with public pricing. See full methodology →
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