Merge pull request #1988 from codeflash-ai/fix/vitest-coverage-override

Fix Vitest coverage collection by overriding coverage.reporter

Author: Saga4

codeflash/languages/javascript/vitest_runner.py

@@ -259,6 +259,13 @@ def _ensure_codeflash_vitest_config(project_root: Path) -> Path | None:
     // incorrectly when tests are in subdirectories (e.g., extensions/discord/test/).
     // Codeflash-generated tests are self-contained and don't require project setup files.
     setupFiles: [],
+    // Override coverage settings to ensure JSON reporter is used.
+    // Vitest's mergeConfig doesn't properly handle nested coverage object merge with
+    // command-line flags, so we explicitly set reporter here to guarantee coverage
+    // files are written to the expected location (coverage-final.json).
+    coverage: {{
+      reporter: ['json'],
+    }},
   }},
 }});
 """
@@ -275,6 +282,10 @@ def _ensure_codeflash_vitest_config(project_root: Path) -> Path | None:
     exclude: ['**/node_modules/**', '**/dist/**'],
     // Use forks pool so timing markers from process.stdout.write flow to parent stdout
     pool: 'forks',
+    // Override coverage settings to ensure JSON reporter is used
+    coverage: {
+      reporter: ['json'],
+    },
   },
 });
 """

tests/languages/javascript/test_vitest_coverage_config.py

@@ -0,0 +1,79 @@
+"""Test that Codeflash Vitest config properly overrides coverage settings."""
+
+from pathlib import Path
+
+import pytest
+
+from codeflash.languages.javascript.vitest_runner import _ensure_codeflash_vitest_config
+
+
+def test_codeflash_vitest_config_overrides_coverage(tmp_path: Path) -> None:
+    project_root = tmp_path.resolve()
+
+    vitest_config = project_root / "vitest.config.ts"
+    vitest_config.write_text(
+        """
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    include: ['test/**/*.test.ts'],
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'lcov'],
+      all: false,
+      thresholds: {
+        lines: 70,
+        functions: 70,
+      },
+    },
+  },
+});
+""",
+        encoding="utf-8",
+    )
+
+    config_path = _ensure_codeflash_vitest_config(project_root)
+
+    assert config_path is not None, "Config should be created"
+    assert config_path.exists(), "Config file should exist"
+
+    config_content = config_path.read_text(encoding="utf-8")
+
+    assert "mergeConfig" in config_content, "Should use mergeConfig"
+    assert "import originalConfig from './vitest.config.ts'" in config_content
+    assert "coverage:" in config_content, (
+        "Config must explicitly override coverage settings to ensure "
+        "json reporter is used regardless of project config"
+    )
+    assert "reporter:" in config_content, "Config must override coverage.reporter to ['json']"
+    assert "['json']" in config_content or '["json"]' in config_content, (
+        "Coverage reporter must be set to ['json'] to ensure coverage files are written in the expected format"
+    )
+
+
+def test_codeflash_vitest_config_without_original_coverage(tmp_path: Path) -> None:
+    project_root = tmp_path.resolve()
+
+    vitest_config = project_root / "vitest.config.ts"
+    vitest_config.write_text(
+        """
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    include: ['test/**/*.test.ts'],
+  },
+});
+""",
+        encoding="utf-8",
+    )
+
+    config_path = _ensure_codeflash_vitest_config(project_root)
+
+    assert config_path is not None
+    assert config_path.exists()
+
+    config_content = config_path.read_text(encoding="utf-8")
+
+    assert "coverage:" in config_content, "Config must explicitly set coverage even when original doesn't have it"