@@ -17,6 +17,7 @@ const {
   buildSyncAutolinkingScript,
   flavorForBuildConfiguration,
   frameworkConditionalSettings,
+  generateReactNativeXcconfig,
   generateXcscheme,
   readScriptPhasesManifest,
 } = require('../generate-spm-xcodeproj');
@@ -604,6 +605,127 @@ describe('configuration-driven framework settings', () => {
   });
 });
 
+describe('generateReactNativeXcconfig', () => {
+  const DEVICE_ONLY = {...FRAMEWORK, slices: [FRAMEWORK.slices[0]]};
+
+  it('writes every setting the app target needs, extending inherited lists', () => {
+    expect(
+      generateReactNativeXcconfig(
+        ['Debug', 'Release'],
+        '../node_modules/react-native',
+        [DEVICE_ONLY],
+        [],
+      ),
+    ).toBe(
+      `// Generated by React Native on every \`spm add\` and \`spm update\`.
+// Do not edit: changes are overwritten.
+
+CLANG_CXX_LANGUAGE_STANDARD = c++20
+REACT_NATIVE_PATH = $(SRCROOT)/../node_modules/react-native
+
+HEADER_SEARCH_PATHS = $(inherited) "$(SRCROOT)/build/generated/autolinking/headers"
+OTHER_LDFLAGS = $(inherited) -ObjC "$(RN_SPM_REACT_BINARY)"
+FRAMEWORK_SEARCH_PATHS = $(inherited) "$(RN_SPM_REACT_SEARCH_PATH)"
+LD_RUNPATH_SEARCH_PATHS = $(inherited) @executable_path/Frameworks
+
+RN_SPM_FLAVOR = release
+RN_SPM_FLAVOR[config=Debug] = debug
+SWIFT_ACTIVE_COMPILATION_CONDITIONS[config=Debug] = $(inherited) DEBUG
+RN_SPM_FLAVOR[config=Release] = release
+
+RN_SPM_REACT_FRAMEWORK[sdk=iphoneos*] = $(SRCROOT)/build/xcframeworks/$(RN_SPM_FLAVOR)/React.xcframework/ios-arm64/React.framework
+RN_SPM_REACT_BINARY[sdk=iphoneos*] = $(SRCROOT)/build/xcframeworks/$(RN_SPM_FLAVOR)/React.xcframework/ios-arm64/React.framework/React
+RN_SPM_REACT_SEARCH_PATH[sdk=iphoneos*] = $(SRCROOT)/build/xcframeworks/$(RN_SPM_FLAVOR)/React.xcframework/ios-arm64
+`,
+    );
+  });
+
+  it('anchors REACT_NATIVE_PATH on SRCROOT itself when react-native sits there', () => {
+    expect(
+      generateReactNativeXcconfig(['Debug'], '', [FRAMEWORK], []),
+    ).toContain('\nREACT_NATIVE_PATH = $(SRCROOT)\n');
+  });
+
+  it("conditions the flavor on the project's own configuration names", () => {
+    const xcconfig = generateReactNativeXcconfig(
+      ['Development', 'Staging'],
+      '../node_modules/react-native',
+      [FRAMEWORK],
+      [],
+    );
+    expect(xcconfig).toContain('RN_SPM_FLAVOR[config=Development] = debug\n');
+    expect(xcconfig).toContain(
+      'SWIFT_ACTIVE_COMPILATION_CONDITIONS[config=Development] = $(inherited) DEBUG\n',
+    );
+    expect(xcconfig).toContain('RN_SPM_FLAVOR[config=Staging] = release\n');
+    expect(xcconfig).not.toContain(
+      'SWIFT_ACTIVE_COMPILATION_CONDITIONS[config=Staging]',
+    );
+    expect(xcconfig).not.toMatch(/\[config=(Debug|Release)\]/);
+  });
+
+  // A configuration duplicated in Xcode keeps the base reference but has no
+  // line of its own until the next sync, and an unset flavor would resolve
+  // every framework path to nothing.
+  it('falls back to the release flavor for a configuration it does not list', () => {
+    const lines = generateReactNativeXcconfig(
+      ['Debug', 'Release'],
+      '../node_modules/react-native',
+      [FRAMEWORK],
+      [],
+    ).split('\n');
+    const fallback = lines.indexOf('RN_SPM_FLAVOR = release');
+    expect(fallback).toBeGreaterThan(-1);
+    expect(fallback).toBeLessThan(
+      lines.findIndex(line => line.startsWith('RN_SPM_FLAVOR[config=')),
+    );
+    expect(
+      lines.some(line =>
+        line.startsWith('SWIFT_ACTIVE_COMPILATION_CONDITIONS ='),
+      ),
+    ).toBe(false);
+  });
+
+  it('writes no plist quoting around conditional keys or path values', () => {
+    const xcconfig = generateReactNativeXcconfig(
+      ['Debug'],
+      '../node_modules/react-native',
+      [FRAMEWORK],
+      [],
+    );
+    expect(xcconfig).toContain(
+      '\nRN_SPM_REACT_BINARY[sdk=iphonesimulator*] = $(SRCROOT)/',
+    );
+    expect(xcconfig).toContain('\nRN_SPM_REACT_SEARCH_PATH[sdk=macosx*] = ');
+    expect(xcconfig).not.toMatch(/^"/m);
+    expect(xcconfig).not.toContain('= "$(SRCROOT)/build/xcframeworks');
+  });
+
+  it('defines the opted-in C++ stable API macros for every configuration', () => {
+    const xcconfig = generateReactNativeXcconfig(
+      ['Debug', 'Release'],
+      '../node_modules/react-native',
+      [FRAMEWORK],
+      ['RN_STRICT_API', 'RN_ALLOW_FRAMEWORKS'],
+    );
+    expect(xcconfig).toContain(
+      '\nGCC_PREPROCESSOR_DEFINITIONS = $(inherited) RN_STRICT_API RN_ALLOW_FRAMEWORKS\n',
+    );
+    expect(xcconfig).not.toContain('GCC_PREPROCESSOR_DEFINITIONS[');
+  });
+
+  it('writes no GCC_PREPROCESSOR_DEFINITIONS without an opted-in macro', () => {
+    expect(
+      generateReactNativeXcconfig(
+        ['Debug', 'Release'],
+        '../node_modules/react-native',
+        [FRAMEWORK],
+        [],
+      ),
+    ).not.toContain('GCC_PREPROCESSOR_DEFINITIONS');
+  });
+});
+
 describe('embed framework phase script', () => {
   const script = buildEmbedFrameworksScript([FRAMEWORK]);