AGENTS.md

Elixirij

A new from-scratch Elixir language support plugin for all IntelliJ Platform-based IDEs.

Rules

• you may be running in parallel with other agents; cooperate to avoid conflicts, but avoid commiting changes made by others
• write tests for every change, unless introducing "declarative" features (code commenter etc.)
• when bugfixing: write minimal reproduction test that fails, then fix, then confirm test passes
• remember to run tests for related changes
• don’t mock IntelliJ Platform internals; prefer real platform test fixtures and pipelines instead
• ensure any feature/bugfix work is covered in @CHANGELOG.md

Code rules

• target the latest IntelliJ Platform version (2026.01+) and modern Elixir language conventions (1.20+)

• use light services and Kotlin coroutines-powered threading model of IntelliJ Platform

• prefer expression functions (fun f() = ...) instead of statement ones (fun f() { ... }) for simple cases

• name tests like this, unless base class (fixtures) requires testCamelCase:

  fun `test something is happening`() { ... }

• prefer parent / child instead of parent.resolve(child) when glueing java.nio.file.Paths together

• when writing fixture tests, always prefer comparing whole actual and expected fixture states:

  Good example:

  fun `test double quote typing`() {
      myFixture.configureByText("test.ex", "x = <caret>")
      myFixture.type('"')
      myFixture.checkResult("x = \"<caret>\"")
  }

  Bad example:

  fun `test double quote typing`() {
      myFixture.configureByText("test.ex", "x = <caret>")
      myFixture.type('"')
      assertTrue("Should have paired quotes", myFixture.editor.document.text.contains("\"<caret>\""))
  }

Tools

# Build whole project
./gradlew buildPlugin

# Run all tests
./gradlew check

# Run single test
./gradlew test --tests "dev.murek.elixirij.lang.ExLexerTest.testIntegerLiterals"

# Regenerate test fixtures
# Use this to regenerate expected output files for ParsingTestCase and similar tests
JAVA_TOOL_OPTIONS="-Didea.tests.overwrite.data=true" ./gradlew test --tests "dev.murek.elixirij.lang.parser.ExParserTest"

# Format code
# This project uses .editorconfig for code style conventions.
# Format code using your IDE's auto-format feature (Ctrl+Alt+L in IntelliJ).
# The build will use the configured EditorConfig settings automatically.