Local Explorer MCP

/** * Tests for line-aware pagination utility * Critical for handling large files, minified files, and mixed-line-length files */ import { describe, it, expect } from 'vitest'; import { sliceByCharRespectLines } from '../../src/utils/pagination.js'; describe('sliceByCharRespectLines', () => { describe('Basic line-aware slicing', () => { it('should slice at line boundaries', () => { const text = 'line1\nline2\nline3\nline4\n'; const result = sliceByCharRespectLines(text, 0, 12); // charLength=12 from position 0 ends at position 12 // text[11] = '\n' (after line2), so we're AT a line boundary // No extension needed expect(result.sliced).toBe('line1\nline2\n'); expect(result.actualOffset).toBe(0); expect(result.actualLength).toBe(12); expect(result.lineCount).toBe(2); expect(result.hasMore).toBe(true); }); it('should adjust offset to line start if mid-line', () => { const text = 'line1\nline2\nline3\n'; // Request starting at position 8 (middle of line2) const result = sliceByCharRespectLines(text, 8, 10); // Should adjust to start of line2 (position 6) expect(result.actualOffset).toBe(6); expect(result.sliced).toBe('line2\nline3\n'); expect(result.lineCount).toBe(2); }); it('should adjust end to line boundary', () => { const text = 'line1\nline2\nline3\n'; // Request 8 chars from start (ends mid-line2) const result = sliceByCharRespectLines(text, 0, 8); // Should extend to end of line2 (include newline) expect(result.sliced).toBe('line1\nline2\n'); expect(result.actualLength).toBe(12); }); }); describe('Minified files (single long line)', () => { it('should handle single-line files', () => { const text = 'x'.repeat(50000); // 50K chars, no newlines const result = sliceByCharRespectLines(text, 0, 10000); // Should return the entire line (no newlines to break on) expect(result.sliced).toBe(text); expect(result.actualLength).toBe(50000); expect(result.lineCount).toBe(0); // No newlines expect(result.hasMore).toBe(false); }); it('should handle single-line file with trailing newline', () => { const text = 'x'.repeat(50000) + '\n'; const result = sliceByCharRespectLines(text, 0, 10000); // Should return entire line including newline expect(result.sliced).toBe(text); expect(result.actualLength).toBe(50001); expect(result.lineCount).toBe(1); }); }); describe('Edge cases', () => { it('should handle empty text', () => { const result = sliceByCharRespectLines('', 0, 100); expect(result.sliced).toBe(''); expect(result.actualOffset).toBe(0); expect(result.actualLength).toBe(0); expect(result.hasMore).toBe(false); expect(result.lineCount).toBe(0); }); it('should handle offset beyond text length', () => { const text = 'line1\nline2\n'; const result = sliceByCharRespectLines(text, 1000, 100); expect(result.sliced).toBe(''); expect(result.hasMore).toBe(false); }); it('should handle charLength larger than remaining text', () => { const text = 'line1\nline2\nline3\n'; const result = sliceByCharRespectLines(text, 0, 100000); // Should return all text expect(result.sliced).toBe(text); expect(result.totalChars).toBe(text.length); expect(result.hasMore).toBe(false); }); it('should handle text without trailing newline', () => { const text = 'line1\nline2\nline3'; const result = sliceByCharRespectLines(text, 12, 10); // Should include last line even without newline expect(result.sliced).toBe('line3'); expect(result.hasMore).toBe(false); }); }); describe('Pagination continuity', () => { it('should provide correct nextOffset for continued pagination', () => { const text = 'line1\nline2\nline3\nline4\nline5\n'; // First page - exactly at line boundary const page1 = sliceByCharRespectLines(text, 0, 12); expect(page1.sliced).toBe('line1\nline2\n'); expect(page1.hasMore).toBe(true); expect(page1.nextOffset).toBe(12); // Second page using nextOffset const page2 = sliceByCharRespectLines(text, page1.nextOffset, 12); expect(page2.sliced).toBe('line3\nline4\n'); expect(page2.hasMore).toBe(true); // Third page const page3 = sliceByCharRespectLines(text, page2.nextOffset, 12); expect(page3.sliced).toBe('line5\n'); expect(page3.hasMore).toBe(false); }); it('should not have overlapping content between pages', () => { const text = 'aaa\nbbb\nccc\nddd\n'; const page1 = sliceByCharRespectLines(text, 0, 5); const page2 = sliceByCharRespectLines(text, page1.nextOffset, 5); // Page 1: charLength=5 from 0 ends at char 5 (middle of bbb), extends to include bbb expect(page1.sliced).toBe('aaa\nbbb\n'); // Page 2: starts from nextOffset (8), extends to include rest expect(page2.sliced).toBe('ccc\nddd\n'); // Verify no overlap const page1LastLine = page1.sliced.split('\n').slice(-2, -1)[0]; const page2FirstLine = page2.sliced.split('\n')[0]; expect(page1LastLine).not.toBe(page2FirstLine); }); }); describe('Mixed line lengths', () => { it('should handle varied line lengths', () => { const text = 'short\n' + 'x'.repeat(1000) + '\nshort again\n'; const result = sliceByCharRespectLines(text, 0, 500); // Should include complete lines, adjusting length as needed expect(result.sliced).toContain('short\n'); expect(result.actualLength).toBeGreaterThan(500); // Adjusted to include full line expect(result.lineCount).toBeGreaterThan(0); }); it('should handle realistic code file structure', () => { const text = [ 'import foo from "bar";', 'import baz from "qux";', '', 'function test() {', ' const x = 1;', ' return x;', '}', '', ].join('\n'); const result = sliceByCharRespectLines(text, 0, 50); // Should slice cleanly at line boundaries expect(result.sliced).toMatch(/\n$/); // Ends with newline expect(result.sliced.split('\n').length - 1).toBe(result.lineCount); }); }); describe('Line count accuracy', () => { it('should count lines correctly', () => { const text = 'a\nb\nc\n'; const result = sliceByCharRespectLines(text, 0, 100); expect(result.lineCount).toBe(3); }); it('should count lines in partial slice', () => { const text = 'a\nb\nc\nd\ne\n'; const result = sliceByCharRespectLines(text, 0, 6); // charLength=6 from 0 ends at position 6 // text[5] = '\n' (after 'c'), so we're AT a line boundary expect(result.sliced).toBe('a\nb\nc\n'); expect(result.lineCount).toBe(3); }); it('should handle lines without newlines', () => { const text = 'single line no newline'; const result = sliceByCharRespectLines(text, 0, 100); expect(result.lineCount).toBe(0); // No newlines }); }); describe('Real-world scenarios', () => { it('should handle ripgrep output with line numbers', () => { const text = [ '1:match one', '2:match two', '3:match three', '4:match four', ].join('\n') + '\n'; const result = sliceByCharRespectLines(text, 0, 25); // Should include complete lines with line numbers intact expect(result.sliced).toMatch(/^\d+:/); // Starts with line number expect(result.sliced).toMatch(/\n$/); // Ends with newline expect(result.sliced.split('\n').every( line => line === '' || /^\d+:/.test(line) )).toBe(true); }); it('should handle JSON output from ripgrep', () => { const text = [ '{"type":"match","data":{"path":{"text":"file.ts"}}}', '{"type":"match","data":{"path":{"text":"file2.ts"}}}', '{"type":"match","data":{"path":{"text":"file3.ts"}}}', ].join('\n') + '\n'; const result = sliceByCharRespectLines(text, 0, 60); // Should not cut JSON objects mid-line const lines = result.sliced.trim().split('\n'); lines.forEach(line => { if (line) { expect(() => JSON.parse(line)).not.toThrow(); } }); }); it('should handle context lines from ripgrep', () => { const text = [ '100-context before', '101:match line', '102-context after', '103-more context', ].join('\n') + '\n'; const result = sliceByCharRespectLines(text, 0, 40); // Should preserve line structure (context markers) expect(result.sliced).toContain('100-'); expect(result.sliced).toContain('101:'); const lines = result.sliced.split('\n'); expect(lines.some(l => l.includes('-'))).toBe(true); expect(lines.some(l => l.includes(':'))).toBe(true); }); }); describe('Performance characteristics', () => { it('should handle large files efficiently', () => { // Create a large file: 10K lines, 100 chars each const lines = Array(10000).fill('x'.repeat(99)).join('\n') + '\n'; const text = lines; // ~1MB const start = Date.now(); const result = sliceByCharRespectLines(text, 0, 10000); const duration = Date.now() - start; // Should complete quickly (< 100ms for 1MB) expect(duration).toBeLessThan(100); expect(result.sliced).toBeTruthy(); }); }); });