How to Use Tabnine Chat in VS Code and JetBrains to Test, Explain, and Refactor Code

Tabnine Chat brings conversational AI directly into the developer workflow inside Visual Studio Code and JetBrains IDEs (such as IntelliJ IDEA, PyCharm, WebStorm, and GoLand). Rather than copying code snippets back and forth into external web chats, developers use Tabnine Chat to generate comprehensive unit tests, unravel complex or legacy logic, and execute surgical refactoring without leaving their editor.

This guide walks through how software engineers interact with Tabnine Chat across VS Code and JetBrains IDEs to handle these three core everyday development tasks, detailing the interface triggers, context-grounding syntax, prompting patterns, and in-editor diff controls.

1. Accessing and Triggering Tabnine Chat

Tabnine Chat operates as an in-IDE side panel and contextual overlay designed for rapid invocation.

Launching the Chat Panel

• In Visual Studio Code: Click the Tabnine logo in the primary Activity Bar on the left sidebar (or press Ctrl+Shift+P / Cmd+Shift+P and search for Tabnine: Open Chat). The chat interface opens docked on the side.
• In JetBrains IDEs: Click the Tabnine tool window tab on the right sidebar (or use the tool windows shortcut). The chat panel opens docked on the right side of the workspace.

The Three Modes of Interaction

1. Method-Level CodeLens: Above function declarations in supported languages (Java, Python, TypeScript, JavaScript, Go, Rust, C#, PHP, Swift, and C/C++), Tabnine displays inline clickable CodeLens actions. Clicking Explain or Test opens the chat panel pre-targeted at that exact method.
2. Global Quick Actions (/): Typing / in the chat input or clicking quick-action chips on a new chat session reveals built-in commands such as /explain-code, /generate-test-for-code, /fix-code, and /document-code.
3. Free-Form Chat with Workspace Context: Developers can highlight code in the active editor, type natural language prompts, and enrich the query using workspace mentions (@ and %).

2. Generating Unit Tests

Writing repetitive test boilerplate and covering tricky edge cases is one of the most effective uses of Tabnine Chat.

Method A: One-Click Quick Action

1. Highlight the function or class you want to test in the editor.
2. In the Tabnine Chat input, type /generate-test-for-code (or select the /generate-test-for-code quick action chip).
3. Tabnine analyzes the highlighted implementation and generates a test suite covering the primary execution path and standard edge cases.

Method B: Context-Enriched Testing Prompts

Built-in actions produce great standard templates, but enterprise projects often require specific testing frameworks, mock configurations, and assertions. Use free-form prompts combined with context anchors:

• Specify Framework and Libraries: Explicitly define the target framework (e.g., JUnit 5 with Mockito, pytest with pytest-mock, Vitest with Jest DOM).
• Ground with Mentions (@ and %):
  • Type @ followed by 2–3 characters to reference workspace classes, interfaces, or dependency types (e.g., @PaymentGateway, @UserRepository).
  • Type % to reference test configuration or helper files (e.g., %test_helpers.py, %setup.ts).
• Define Scenario Requirements: Request edge cases, negative tests, and boundary value conditions.

Prompt Example:
Generate a comprehensive unit test suite for the selected method using JUnit 5 and Mockito.
Context: @OrderRepository, @PaymentClient
Requirements:
1. Test successful order placement with 200 OK.
2. Test insufficient inventory throwing OutOfStockException.
3. Test payment failure rollback.
4. Mock all database calls and remote API requests.

Team-Wide Test Commands (.tabnine_commands)

If your engineering team enforces a specific test harness (e.g., custom test wrappers or mocking conventions), define a shared custom command:

1. In Tabnine Chat, click Settings (gear icon) > Add under Define custom commands.
2. Name the command (e.g., /test-service) and specify the prompt template using the $selected_code token.
3. Export and commit the generated .tabnine_commands file to the root of your Git repository so every team member shares identical test prompting standards.

3. Explaining Code Logic

Deciphering legacy code, complex regex, recursive algorithms, or unfamiliar third-party libraries can stall development. Tabnine Chat breaks down code logic interactively.

Quick Logic Explanation

1. Highlight the unfamiliar block of code in VS Code or JetBrains.
2. Click the floating Explain CodeLens directly above the method, or type /explain-code in the chat window.
3. Tabnine returns a step-by-step breakdown explaining:
   • The core purpose and input/output parameters.
   • Key conditional branches and loops.
   • Potential side effects or dependencies.

Interactive Deep Dives

Unlike static documentation, Tabnine Chat supports multi-turn inquiry. Once the initial explanation appears, follow up with targeted technical questions:

• "What is the time and space complexity of this algorithm?"
• "Are there concurrency or thread-safety risks in the cache invalidation branch?"
• "What exceptions can this block throw if the external payload has null values?"

Customizing Chat Tone and Depth

In Tabnine Chat Settings:

• Response Length: Switch between Concise (brief bullet points for quick glance) and Comprehensive (in-depth line-by-line analysis with architectural context).
• Custom Chat Behaviors: Set a persistent persona prompt (e.g., "Explain code like a senior software architect with emphasis on edge cases and performance bottlenecks").

4. Refactoring Existing Functions

Refactoring legacy functions requires precision to improve readability and maintainability without altering runtime behavior.

Constructing an Effective Refactoring Prompt

Avoid generic requests like "clean up this code". Follow Tabnine's structured prompting strategy:

1. Task: Specify the exact refactoring technique (e.g., Extract Method, Replace Nested Conditional with Guard Clauses, Convert Loop to Streams/LINQ).
2. Context: Link relevant domain models or helpers using @ClassName.
3. Constraints: Explicitly declare boundary conditions, such as "Preserve public function signature" and "Maintain identical return types and exception semantics".
4. Validation: Instruct the model to ensure the refactored code satisfies existing unit tests.

Prompt Example:
Goal: Refactor the selected function to reduce cyclomatic complexity.
Technique: Replace deeply nested if-else blocks with guard clauses and early returns.
Constraints:
- Preserve the method signature and public API.
- Do not modify error logging formats.
- Retain identical runtime behavior and exception handling.
Source: @OrderValidationService

Reviewing and Applying Refactored Code in the IDE

Tabnine provides dedicated UI mechanisms so you do not have to copy and paste manually:

5. Best Practices for Maximizing Accuracy

• Keep Conversations Focused: Context windows carry prior conversation history. When switching from refactoring an authentication module to writing tests for a billing service, click the + (New Conversation) icon. This clears old tokens and avoids hallucinated crossover context.
• Combine Selections with Workspace Mentions: The editor's selected code and active file receive the highest context priority. Use @ for types and % for files to pull in distant symbols without cluttering the prompt.
• Privacy and Compliance: Tabnine processes code requests under strict privacy protections. Tabnine models are trained exclusively on permissively licensed open-source code, never train on private customer code, and enterprise plans allow organizations to choose between protected proprietary models and switchable LLMs.

By pairing quick actions with structured prompts, CodeLens triggers, and in-IDE diff reviews, developers turn Tabnine Chat into a fast, privacy-conscious co-pilot for testing, understanding, and modernizing code in both VS Code and JetBrains IDEs.

References

• Overview | Tabnine Docs
• Tabnine Chat | Tabnine Docs
• Interacting with Tabnine Chat | Tabnine Docs
• Reviewing suggestions | Tabnine Docs
• Launching Tabnine Chat | Tabnine Docs
• Tabnine's Prompting Guide | Tabnine Docs