feat: add --show-errors flag to show detailed compiler errors

src/args.mts

@@ -0,0 +1,26 @@
+type Command = 'check-files' | 'overwrite' | 'stage-record-file' | 'check-all'
+
+type ParsedArgs = {
+    command: Command
+    filePaths: string[]
+    showErrors: boolean
+}
+
+const FLAG_TO_COMMAND: Record<string, Command> = {
+    '--check-files': 'check-files',
+    '--overwrite': 'overwrite',
+    '--stage-record-file': 'stage-record-file',
+}
+
+function parseArgs(argv: string[]): ParsedArgs {
+    const showErrors = argv.includes('--show-errors')
+    const argsWithoutShowErrors = argv.filter((arg) => arg !== '--show-errors')
+
+    const flag = argsWithoutShowErrors[0] ?? ''
+    const filePaths = argsWithoutShowErrors.slice(1)
+    const command = FLAG_TO_COMMAND[flag] ?? 'check-all'
+
+    return { command, filePaths, showErrors }
+}
+
+export { parseArgs, type ParsedArgs }

src/args.test.mts

@@ -0,0 +1,68 @@
+import { describe, expect, it } from 'vitest'
+import { parseArgs } from './args.mjs'
+
+describe('parseArgs', () => {
+    it('parses --check-files with files', () => {
+        const result = parseArgs(['--check-files', 'file.ts'])
+        expect(result).toEqual({
+            command: 'check-files',
+            filePaths: ['file.ts'],
+            showErrors: false,
+        })
+    })
+
+    it('parses --show-errors before command', () => {
+        const result = parseArgs(['--show-errors', '--check-files', 'file.ts'])
+        expect(result).toEqual({
+            command: 'check-files',
+            filePaths: ['file.ts'],
+            showErrors: true,
+        })
+    })
+
+    it('parses --show-errors after command', () => {
+        const result = parseArgs(['--check-files', '--show-errors', 'file.ts'])
+        expect(result.showErrors).toBe(true)
+        expect(result.filePaths).toEqual(['file.ts'])
+    })
+
+    it('parses --show-errors at end', () => {
+        const result = parseArgs(['--check-files', 'file.ts', '--show-errors'])
+        expect(result.showErrors).toBe(true)
+        expect(result.filePaths).toEqual(['file.ts'])
+    })
+
+    it('parses --overwrite with --show-errors', () => {
+        const result = parseArgs(['--show-errors', '--overwrite'])
+        expect(result.command).toBe('overwrite')
+        expect(result.showErrors).toBe(true)
+    })
+
+    it('defaults to check-all when no command', () => {
+        const result = parseArgs([])
+        expect(result.command).toBe('check-all')
+    })
+
+    it('parses --stage-record-file with files', () => {
+        const result = parseArgs(['--stage-record-file', 'file1.ts', 'file2.ts'])
+        expect(result).toEqual({
+            command: 'stage-record-file',
+            filePaths: ['file1.ts', 'file2.ts'],
+            showErrors: false,
+        })
+    })
+
+    it('parses --overwrite without files', () => {
+        const result = parseArgs(['--overwrite'])
+        expect(result).toEqual({
+            command: 'overwrite',
+            filePaths: [],
+            showErrors: false,
+        })
+    })
+
+    it('treats unknown flags as check-all command', () => {
+        const result = parseArgs(['--unknown-flag'])
+        expect(result.command).toBe('check-all')
+    })
+})

src/index.integration.test.mts

@@ -33,65 +33,95 @@ describe('CLI', () => {
         }
     })
 
-    it('runs check on all files when no flag provided', () => {
-        const output = runCLI()
+    describe('no flag (default check-all)', () => {
+        it('runs check on all files when no flag provided', () => {
+            const output = runCLI()
 
-        expect(output).toContain('🔍 Checking all 5 source files for React Compiler errors…')
-        expect(output).toContain('⚠️  Found 4 React Compiler issues across 2 files')
-        expect(() => JSON.parse(readFileSync(recordsPath, 'utf8'))).toThrow()
-    })
+            expect(output).toContain('🔍 Checking all 5 source files for React Compiler errors…')
+            expect(output).toContain('⚠️  Found 4 React Compiler issues across 2 files')
+            expect(() => JSON.parse(readFileSync(recordsPath, 'utf8'))).toThrow()
+        })
+
+        it('--show-errors works with default check-all', () => {
+            const output = runCLI(['--show-errors'])
 
-    it('accepts --check-files flag with file arguments', () => {
-        const output = runCLI(['--check-files', 'src/bad-component.tsx', 'src/bad-hook.ts'])
-
-        expect(output).toContain('🔍 Checking 2 files for React Compiler errors…')
-        expect(output).toContain('React Compiler errors have increased in:')
-        expect(output).toContain('• src/bad-component.tsx: +1')
-        expect(output).toContain('• src/bad-hook.ts: +3')
-        expect(output).toContain('Please fix the errors and run the command again.')
-        expect(output).not.toContain('src/good-component.tsx')
-        expect(output).not.toContain('src/good-hook.ts')
-        expect(() => JSON.parse(readFileSync(recordsPath, 'utf8'))).toThrow()
+            expect(output).toContain('Found 4 React Compiler issues')
+            expect(output).toContain('Detailed errors:')
+            expect(output).toMatch(/Line \d+:/)
+        })
     })
 
-    it('errors when file does not exist', () => {
-        const output = runCLI(['--check-files', 'src/nonexistent-file.tsx'])
+    describe('--check-files', () => {
+        it('accepts --check-files flag with file arguments', () => {
+            const output = runCLI(['--check-files', 'src/bad-component.tsx', 'src/bad-hook.ts'])
 
-        expect(output).toContain('File not found: src/nonexistent-file.tsx')
-    })
+            expect(output).toContain('🔍 Checking 2 files for React Compiler errors…')
+            expect(output).toContain('React Compiler errors have increased in:')
+            expect(output).toContain('• src/bad-component.tsx: +1')
+            expect(output).toContain('• src/bad-hook.ts: +3')
+            expect(output).toContain('Please fix the errors and run the command again.')
+            expect(output).not.toContain('src/good-component.tsx')
+            expect(output).not.toContain('src/good-hook.ts')
+            expect(() => JSON.parse(readFileSync(recordsPath, 'utf8'))).toThrow()
+        })
+
+        it('errors when file does not exist', () => {
+            const output = runCLI(['--check-files', 'src/nonexistent-file.tsx'])
+
+            expect(output).toContain('File not found: src/nonexistent-file.tsx')
+        })
+
+        it('handles shell-escaped file paths with $ character', () => {
+            // Simulate what CI tools do when passing filenames with $ through shell variables
+            const output = runCLI(['--check-files', 'src/route.\\$param.tsx'])
+
+            expect(output).toContain('🔍 Checking 1 file for React Compiler errors…')
+            expect(output).not.toContain('File not found')
+        })
 
-    it('handles shell-escaped file paths with $ character', () => {
-        // Simulate what CI tools do when passing filenames with $ through shell variables
-        const output = runCLI(['--check-files', 'src/route.\\$param.tsx'])
+        it('--show-errors shows detailed error info', () => {
+            const output = runCLI(['--check-files', '--show-errors', 'src/bad-hook.ts'])
 
-        expect(output).toContain('🔍 Checking 1 file for React Compiler errors…')
-        expect(output).not.toContain('File not found')
+            expect(output).toContain('React Compiler errors have increased')
+            expect(output).toContain('Detailed errors:')
+            expect(output).toMatch(/Line \d+:/)
+        })
     })
 
-    it('accepts --overwrite flag', () => {
-        const output = runCLI(['--overwrite'])
-
-        expect(output).toContain(
-            '🔍 Checking all 5 source files for React Compiler errors and recreating records…',
-        )
-        expect(output).toContain(
-            '✅ Records saved to .react-compiler.rec.json. Found 4 total React Compiler issues across 2 files',
-        )
-
-        const records = JSON.parse(readFileSync(recordsPath, 'utf8'))
-        expect(records.recordVersion).toBe(1)
-        expect(records['react-compiler-version']).toBe('1.0.0')
-        expect(records.files).toEqual({
-            'src/bad-component.tsx': {
-                CompileError: 1,
-            },
-            'src/bad-hook.ts': {
-                CompileError: 3,
-            },
+    describe('--overwrite', () => {
+        it('accepts --overwrite flag', () => {
+            const output = runCLI(['--overwrite'])
+
+            expect(output).toContain(
+                '🔍 Checking all 5 source files for React Compiler errors and recreating records…',
+            )
+            expect(output).toContain(
+                '✅ Records saved to .react-compiler.rec.json. Found 4 total React Compiler issues across 2 files',
+            )
+
+            const records = JSON.parse(readFileSync(recordsPath, 'utf8'))
+            expect(records.recordVersion).toBe(1)
+            expect(records['react-compiler-version']).toBe('1.0.0')
+            expect(records.files).toEqual({
+                'src/bad-component.tsx': {
+                    CompileError: 1,
+                },
+                'src/bad-hook.ts': {
+                    CompileError: 3,
+                },
+            })
+        })
+
+        it('--show-errors shows detailed errors while saving', () => {
+            const output = runCLI(['--overwrite', '--show-errors'])
+
+            expect(output).toContain('Records saved to')
+            expect(output).toContain('Detailed errors:')
+            expect(output).toMatch(/Line \d+:/)
         })
     })
 
-    describe('--stage-record-file flag', () => {
+    describe('--stage-record-file', () => {
         it('exits cleanly when no files provided', () => {
             const output = runCLI(['--stage-record-file'])
 
@@ -113,6 +143,14 @@ describe('CLI', () => {
             expect(output).toContain('• src/bad-hook.ts: +3')
         })
 
+        it('--stage-record-file --show-errors shows detailed errors', () => {
+            const output = runCLI(['--stage-record-file', '--show-errors', 'src/bad-hook.ts'])
+
+            expect(output).toContain('React Compiler errors have increased')
+            expect(output).toContain('Detailed errors:')
+            expect(output).toMatch(/Line \d+:/)
+        })
+
         it('checks provided files with existing records', () => {
             // First create records
             runCLI(['--overwrite'])