test(snapshot): Avoid mutating example app sources

cameroncooke · codex · cameroncooke · commit b7e981389ea8 · 2026-05-01T22:01:30.000+01:00
Trigger compiler-error snapshot cases with a guarded Swift compile flag instead of patching example project files during test execution. This keeps snapshot tests deterministic and avoids leaving tracked source files corrupted if a run is interrupted. Refs GH-387 Co-Authored-By: Codex <codex@openai.com>
diff --git a/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift b/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift
@@ -28,3 +28,7 @@ struct CalculatorApp: App {
 #Preview {
     ContentView()
 }
+
+#if SNAPSHOT_COMPILER_ERROR
+private let snapshotCompilerError: Int = "not an int"
+#endif
diff --git a/example_projects/macOS/MCPTest/MCPTestApp.swift b/example_projects/macOS/MCPTest/MCPTestApp.swift
@@ -15,3 +15,7 @@ struct MCPTestApp: App {
         }
     }
 }
+
+#if SNAPSHOT_COMPILER_ERROR
+private let snapshotCompilerError: Int = "not an int"
+#endif
diff --git a/src/snapshot-tests/__fixtures__/cli/device/build--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/device/build--error-compiler.txt
@@ -10,7 +10,7 @@
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32:42
+    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33:42
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_device_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/device/build-and-run--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/device/build-and-run--error-compiler.txt
@@ -11,7 +11,7 @@
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32:42
+    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33:42
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_run_device_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/device/test--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/device/test--error-compiler.txt
@@ -16,7 +16,7 @@ Discovered 1 test(s):
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32:42
+    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33:42
 
 ❌ Test failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/test_device_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/macos/build--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/macos/build--error-compiler.txt
@@ -10,7 +10,7 @@
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/macOS/MCPTest/MCPTestApp.swift:19:42
+    example_projects/macOS/MCPTest/MCPTestApp.swift:20:42
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_macos_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/macos/build-and-run--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/macos/build-and-run--error-compiler.txt
@@ -10,7 +10,7 @@
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/macOS/MCPTest/MCPTestApp.swift:19:42
+    example_projects/macOS/MCPTest/MCPTestApp.swift:20:42
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_run_macos_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/macos/test--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/macos/test--error-compiler.txt
@@ -17,7 +17,7 @@ Discovered 2 test(s):
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/macOS/MCPTest/MCPTestApp.swift:19:42
+    example_projects/macOS/MCPTest/MCPTestApp.swift:20:42
 
 ❌ Test failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/test_macos_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/simulator/build--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/simulator/build--error-compiler.txt
@@ -11,7 +11,7 @@
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32:42
+    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33:42
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_sim_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/simulator/build-and-run--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/simulator/build-and-run--error-compiler.txt
@@ -11,7 +11,7 @@
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32:42
+    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33:42
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_run_sim_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/cli/simulator/test--error-compiler.txt b/src/snapshot-tests/__fixtures__/cli/simulator/test--error-compiler.txt
@@ -16,7 +16,7 @@ Discovered 1 test(s):
 Compiler Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32:42
+    example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33:42
 
 ❌ Test failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/test_sim_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/json/device/build--error-compiler.json b/src/snapshot-tests/__fixtures__/json/device/build--error-compiler.json
@@ -25,7 +25,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32"
+          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33"
         }
       ]
     }
diff --git a/src/snapshot-tests/__fixtures__/json/device/build-and-run--error-compiler.json b/src/snapshot-tests/__fixtures__/json/device/build-and-run--error-compiler.json
@@ -27,7 +27,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32"
+          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33"
         }
       ]
     }
diff --git a/src/snapshot-tests/__fixtures__/json/device/test--error-compiler.json b/src/snapshot-tests/__fixtures__/json/device/test--error-compiler.json
@@ -42,7 +42,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32"
+          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33"
         }
       ],
       "testFailures": []
diff --git a/src/snapshot-tests/__fixtures__/json/macos/build--error-compiler.json b/src/snapshot-tests/__fixtures__/json/macos/build--error-compiler.json
@@ -25,7 +25,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:19"
+          "location": "<ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:20"
         }
       ]
     }
diff --git a/src/snapshot-tests/__fixtures__/json/macos/build-and-run--error-compiler.json b/src/snapshot-tests/__fixtures__/json/macos/build-and-run--error-compiler.json
@@ -25,7 +25,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:19"
+          "location": "<ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:20"
         }
       ]
     }
diff --git a/src/snapshot-tests/__fixtures__/json/macos/test--error-compiler.json b/src/snapshot-tests/__fixtures__/json/macos/test--error-compiler.json
@@ -42,7 +42,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:19"
+          "location": "<ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:20"
         }
       ],
       "testFailures": []
diff --git a/src/snapshot-tests/__fixtures__/json/simulator/build--error-compiler.json b/src/snapshot-tests/__fixtures__/json/simulator/build--error-compiler.json
@@ -25,7 +25,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32"
+          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33"
         }
       ]
     }
diff --git a/src/snapshot-tests/__fixtures__/json/simulator/build-and-run--error-compiler.json b/src/snapshot-tests/__fixtures__/json/simulator/build-and-run--error-compiler.json
@@ -25,7 +25,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32"
+          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33"
         }
       ]
     }
diff --git a/src/snapshot-tests/__fixtures__/json/simulator/test--error-compiler.json b/src/snapshot-tests/__fixtures__/json/simulator/test--error-compiler.json
@@ -40,7 +40,7 @@
       "errors": [
         {
           "message": "cannot convert value of type 'String' to specified type 'Int'",
-          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32"
+          "location": "<ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33"
         }
       ],
       "testFailures": []
diff --git a/src/snapshot-tests/__fixtures__/mcp/device/build--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/device/build--error-compiler.txt
@@ -10,7 +10,7 @@
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32
+    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_device_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/device/build-and-run--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/device/build-and-run--error-compiler.txt
@@ -11,7 +11,7 @@
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32
+    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_run_device_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/device/test--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/device/test--error-compiler.txt
@@ -16,7 +16,7 @@ Discovered 1 test(s):
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32
+    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33
 
 ❌ Test failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/test_device_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/macos/build--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/macos/build--error-compiler.txt
@@ -10,7 +10,7 @@
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:19
+    <ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:20
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_macos_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/macos/build-and-run--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/macos/build-and-run--error-compiler.txt
@@ -10,7 +10,7 @@
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:19
+    <ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:20
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_run_macos_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/macos/test--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/macos/test--error-compiler.txt
@@ -17,7 +17,7 @@ Discovered 2 test(s):
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:19
+    <ROOT>/example_projects/macOS/MCPTest/MCPTestApp.swift:20
 
 ❌ Test failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/test_macos_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/simulator/build--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/simulator/build--error-compiler.txt
@@ -11,7 +11,7 @@
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32
+    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_sim_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/simulator/build-and-run--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/simulator/build-and-run--error-compiler.txt
@@ -11,7 +11,7 @@
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32
+    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33
 
 ❌ Build failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/build_run_sim_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/__fixtures__/mcp/simulator/test--error-compiler.txt b/src/snapshot-tests/__fixtures__/mcp/simulator/test--error-compiler.txt
@@ -16,7 +16,7 @@ Discovered 1 test(s):
 Errors (1):
 
   ✗ cannot convert value of type 'String' to specified type 'Int'
-    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:32
+    <ROOT>/example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift:33
 
 ❌ Test failed. (⏱️ <DURATION>)
   └ Build Logs: <HOME>/Library/Developer/XcodeBuildMCP/logs/test_sim_<TIMESTAMP>_pid<PID>.log
diff --git a/src/snapshot-tests/suites/device-suite.ts b/src/snapshot-tests/suites/device-suite.ts
@@ -6,9 +6,9 @@ import {
   extractProcessIdFromSnapshotOutput,
 } from '../output-parsers.ts';
 import {
+  compilerErrorExtraArgs,
   createHarnessForRuntime,
   createWorkflowFixtureMatcher,
-  withCalculatorAppCompilerError,
 } from './helpers.ts';
 
 const WORKSPACE = 'example_projects/iOS_Calculator/CalculatorApp.xcworkspace';
@@ -67,12 +67,11 @@ export function registerDeviceSnapshotSuite(runtime: SnapshotRuntime): void {
       });
 
       it('error - compiler error', async () => {
-        const { text, isError } = await withCalculatorAppCompilerError(() =>
-          harness.invoke('device', 'build', {
-            workspacePath: WORKSPACE,
-            scheme: 'CalculatorApp',
-          }),
-        );
+        const { text, isError } = await harness.invoke('device', 'build', {
+          workspacePath: WORKSPACE,
+          scheme: 'CalculatorApp',
+          extraArgs: compilerErrorExtraArgs(),
+        });
         expect(isError).toBe(true);
         expectFixture(text, 'build--error-compiler');
       });
@@ -156,13 +155,12 @@ export function registerDeviceSnapshotSuite(runtime: SnapshotRuntime): void {
       });
 
       it('error - compiler error', async () => {
-        const { text, isError } = await withCalculatorAppCompilerError(() =>
-          harness.invoke('device', 'build-and-run', {
-            workspacePath: WORKSPACE,
-            scheme: 'CalculatorApp',
-            deviceId: DEVICE_ID,
-          }),
-        );
+        const { text, isError } = await harness.invoke('device', 'build-and-run', {
+          workspacePath: WORKSPACE,
+          scheme: 'CalculatorApp',
+          deviceId: DEVICE_ID,
+          extraArgs: compilerErrorExtraArgs(),
+        });
         expect(isError).toBe(true);
         expectFixture(text, 'build-and-run--error-compiler');
       });
@@ -245,14 +243,14 @@ export function registerDeviceSnapshotSuite(runtime: SnapshotRuntime): void {
       }, 300_000);
 
       it('error - compiler error', async () => {
-        const { text, isError } = await withCalculatorAppCompilerError(() =>
-          harness.invoke('device', 'test', {
-            workspacePath: WORKSPACE,
-            scheme: 'CalculatorApp',
-            deviceId: DEVICE_ID,
-            extraArgs: ['-only-testing:CalculatorAppTests/CalculatorAppTests/testAddition'],
-          }),
-        );
+        const { text, isError } = await harness.invoke('device', 'test', {
+          workspacePath: WORKSPACE,
+          scheme: 'CalculatorApp',
+          deviceId: DEVICE_ID,
+          extraArgs: compilerErrorExtraArgs([
+            '-only-testing:CalculatorAppTests/CalculatorAppTests/testAddition',
+          ]),
+        });
         expect(isError).toBe(true);
         expectFixture(text, 'test--error-compiler');
       }, 300_000);
diff --git a/src/snapshot-tests/suites/helpers.ts b/src/snapshot-tests/suites/helpers.ts
@@ -1,20 +1,10 @@
-import fs from 'node:fs';
-import path from 'node:path';
 import type { SnapshotRuntime, WorkflowSnapshotHarness } from '../contracts.ts';
 import { createFixtureMatcher, type FixtureMatchOptions } from '../fixture-io.ts';
 import { createSnapshotHarness } from '../harness.ts';
 import { createJsonSnapshotHarness } from '../json-harness.ts';
 import { createMcpSnapshotHarness } from '../mcp-harness.ts';
 
-const CALCULATOR_APP_SOURCE_PATH = path.resolve(
-  process.cwd(),
-  'example_projects/iOS_Calculator/CalculatorApp/CalculatorApp.swift',
-);
-const MACOS_APP_SOURCE_PATH = path.resolve(
-  process.cwd(),
-  'example_projects/macOS/MCPTest/MCPTestApp.swift',
-);
-const COMPILER_ERROR_SNIPPET = 'private let snapshotCompilerError: Int = "not an int"';
+const COMPILER_ERROR_EXTRA_ARGS = ['OTHER_SWIFT_FLAGS=$(inherited) -D SNAPSHOT_COMPILER_ERROR'];
 
 export function createHarnessForRuntime(
   runtime: SnapshotRuntime,
@@ -34,36 +24,8 @@ export interface WorkflowFixtureMatcherOptions extends FixtureMatchOptions {
   fixtureRuntime?: SnapshotRuntime;
 }
 
-export async function withCalculatorAppCompilerError<T>(action: () => Promise<T>): Promise<T> {
-  const originalSource = fs.readFileSync(CALCULATOR_APP_SOURCE_PATH, 'utf8');
-
-  try {
-    fs.writeFileSync(
-      CALCULATOR_APP_SOURCE_PATH,
-      `${originalSource}\n${COMPILER_ERROR_SNIPPET}\n`,
-      'utf8',
-    );
-
-    return await action();
-  } finally {
-    fs.writeFileSync(CALCULATOR_APP_SOURCE_PATH, originalSource, 'utf8');
-  }
-}
-
-export async function withMacosAppCompilerError<T>(action: () => Promise<T>): Promise<T> {
-  const originalSource = fs.readFileSync(MACOS_APP_SOURCE_PATH, 'utf8');
-
-  try {
-    fs.writeFileSync(
-      MACOS_APP_SOURCE_PATH,
-      `${originalSource}\n${COMPILER_ERROR_SNIPPET}\n`,
-      'utf8',
-    );
-
-    return await action();
-  } finally {
-    fs.writeFileSync(MACOS_APP_SOURCE_PATH, originalSource, 'utf8');
-  }
+export function compilerErrorExtraArgs(extraArgs: string[] = []): string[] {
+  return [...extraArgs, ...COMPILER_ERROR_EXTRA_ARGS];
 }
 
 export function createWorkflowFixtureMatcher(
diff --git a/src/snapshot-tests/suites/macos-suite.ts b/src/snapshot-tests/suites/macos-suite.ts
diff --git a/src/snapshot-tests/suites/simulator-suite.ts b/src/snapshot-tests/suites/simulator-suite.ts

Original file line number	Diff line number	Diff line change
`@@ -28,3 +28,7 @@ struct CalculatorApp: App {`
`28`	`28`	`#Preview {`
`29`	`29`	`ContentView()`
`30`	`30`	`}`
	`31`	`+`
	`32`	`+#if SNAPSHOT_COMPILER_ERROR`
	`33`	`+private let snapshotCompilerError: Int = "not an int"`
	`34`	`+#endif`
Original file line number	Diff line number	Diff line change
`@@ -15,3 +15,7 @@ struct MCPTestApp: App {`
`15`	`15`	`}`
`16`	`16`	`}`
`17`	`17`	`}`
	`18`	`+`
	`19`	`+#if SNAPSHOT_COMPILER_ERROR`
	`20`	`+private let snapshotCompilerError: Int = "not an int"`
	`21`	`+#endif`