speculative partial fix for typed configs

packages/core/src/context/sidecar/SidecarLoader.test.ts

@@ -0,0 +1,62 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import * as fs from 'node:fs';
+import { SidecarLoader } from './SidecarLoader.js';
+import { defaultSidecarProfile } from './profiles.js';
+
+vi.mock('node:fs');
+
+describe('SidecarLoader', () => {
+  beforeEach(() => {
+    vi.resetAllMocks();
+  });
+
+  const mockConfig = {
+    getExperimentalContextSidecarConfig: () => '/path/to/sidecar.json'
+  } as any;
+
+  it('returns default profile if file does not exist', () => {
+    vi.mocked(fs.existsSync).mockReturnValue(false);
+    const result = SidecarLoader.fromConfig(mockConfig);
+    expect(result).toBe(defaultSidecarProfile);
+  });
+
+  it('returns default profile if file exists but is 0 bytes', () => {
+    vi.mocked(fs.existsSync).mockReturnValue(true);
+    vi.mocked(fs.statSync).mockReturnValue({ size: 0 } as any);
+    const result = SidecarLoader.fromConfig(mockConfig);
+    expect(result).toBe(defaultSidecarProfile);
+  });
+
+  it('throws an error if file is empty whitespace', () => {
+    vi.mocked(fs.existsSync).mockReturnValue(true);
+    vi.mocked(fs.statSync).mockReturnValue({ size: 5 } as any);
+    vi.mocked(fs.readFileSync).mockReturnValue('   \n  ');
+    
+    expect(() => SidecarLoader.fromConfig(mockConfig)).toThrow('is empty');
+  });
+
+  it('returns parsed config if file is valid', () => {
+    vi.mocked(fs.existsSync).mockReturnValue(true);
+    vi.mocked(fs.statSync).mockReturnValue({ size: 100 } as any);
+    const validConfig = {
+      budget: { retainedTokens: 1000, maxTokens: 2000 },
+      gcBackstop: { strategy: 'truncate', target: 'max' },
+      pipelines: []
+    };
+    vi.mocked(fs.readFileSync).mockReturnValue(JSON.stringify(validConfig));
+    const result = SidecarLoader.fromConfig(mockConfig);
+    expect(result).toEqual(validConfig);
+  });
+
+  it('throws an error if schema validation fails', () => {
+    vi.mocked(fs.existsSync).mockReturnValue(true);
+    vi.mocked(fs.statSync).mockReturnValue({ size: 100 } as any);
+    const invalidConfig = {
+      budget: { retainedTokens: "invalid string" }, // Invalid type
+      pipelines: []
+    };
+    vi.mocked(fs.readFileSync).mockReturnValue(JSON.stringify(invalidConfig));
+    
+    expect(() => SidecarLoader.fromConfig(mockConfig)).toThrow('Validation error:');
+  });
+});