Fall back to Xcode DerivedData when using --skip-build

Sources/XcodeSupport/Xcodebuild.swift

@@ -61,13 +61,19 @@ public final class Xcodebuild {
 
     public func indexStorePath(project: XcodeProjectlike, schemes: [String]) throws -> FilePath {
         let derivedDataPath = try derivedDataPath(for: project, schemes: schemes)
-        let pathsToTry = ["Index.noindex/DataStore", "Index/DataStore"]
-            .map { derivedDataPath.appending($0) }
-        guard let path = pathsToTry.first(where: { $0.exists }) else {
-            throw PeripheryError.indexStoreNotFound(derivedDataPath: derivedDataPath.string)
+
+        if let path = findIndexStorePath(in: derivedDataPath) {
+            return path
         }
 
-        return path
+        // Periphery's own DerivedData may not exist when --skip-build is used and
+        // the project was built by Xcode or xcodebuild. Fall back to searching
+        // Xcode's default DerivedData location for a matching project directory.
+        if let path = findIndexStoreInDefaultDerivedData(projectName: project.name) {
+            return path
+        }
+
+        throw PeripheryError.indexStoreNotFound(derivedDataPath: derivedDataPath.string)
     }
 
     func schemes(project: XcodeProjectlike, additionalArguments: [String]) throws -> Set<String> {
@@ -119,6 +125,51 @@ public final class Xcodebuild {
         }
     }
 
+    func findIndexStorePath(in derivedDataPath: FilePath) -> FilePath? {
+        ["Index.noindex/DataStore", "Index/DataStore"]
+            .map { derivedDataPath.appending($0) }
+            .first { $0.exists }
+    }
+
+    func findIndexStoreInDefaultDerivedData(projectName: String) -> FilePath? {
+        let defaultDerivedData = FilePath(
+            NSHomeDirectory()
+        ).appending("Library/Developer/Xcode/DerivedData")
+
+        return findIndexStoreInDerivedData(projectName: projectName, derivedDataRoot: defaultDerivedData)
+    }
+
+    func findIndexStoreInDerivedData(projectName: String, derivedDataRoot: FilePath) -> FilePath? {
+        guard derivedDataRoot.exists else { return nil }
+
+        // Xcode names DerivedData subdirectories as "<ProjectName>-<hash>".
+        // Find the most recently modified one matching the project name.
+        let fm = FileManager.default
+        guard let entries = try? fm.contentsOfDirectory(atPath: derivedDataRoot.string) else {
+            return nil
+        }
+
+        let candidates = entries
+            .filter { $0.hasPrefix("\(projectName)-") }
+            .compactMap { entry -> (path: FilePath, modified: Date)? in
+                let entryPath = derivedDataRoot.appending(entry)
+                guard let attrs = try? fm.attributesOfItem(atPath: entryPath.string),
+                      let modified = attrs[.modificationDate] as? Date else {
+                    return nil
+                }
+                return (entryPath, modified)
+            }
+            .sorted { $0.modified > $1.modified }
+
+        for candidate in candidates {
+            if let path = findIndexStorePath(in: candidate.path) {
+                return path
+            }
+        }
+
+        return nil
+    }
+
     private func derivedDataPath(for project: XcodeProjectlike, schemes: [String]) throws -> FilePath {
         // Given a project with two schemes: A and B, a scenario can arise where the index store contains conflicting
         // data. If scheme A is built, then the source file modified and then scheme B built, the index store will

Tests/XcodeTests/XcodebuildIndexStoreTest.swift

@@ -0,0 +1,144 @@
+import Foundation
+import Logger
+import SystemPackage
+@testable import XcodeSupport
+import XCTest
+
+final class XcodebuildIndexStoreTest: XCTestCase {
+    private var xcodebuild: Xcodebuild!
+    private var tmpDir: FilePath!
+
+    override func setUp() {
+        super.setUp()
+
+        let logger = Logger(quiet: true, verbose: false, colorMode: .never)
+        let shell = ShellMock(output: "")
+        xcodebuild = Xcodebuild(shell: shell, logger: logger)
+        tmpDir = FilePath(NSTemporaryDirectory()).appending("XcodebuildIndexStoreTest-\(UUID().uuidString)")
+        try! FileManager.default.createDirectory(atPath: tmpDir.string, withIntermediateDirectories: true)
+    }
+
+    override func tearDown() {
+        try? FileManager.default.removeItem(atPath: tmpDir.string)
+        xcodebuild = nil
+        tmpDir = nil
+        super.tearDown()
+    }
+
+    // MARK: - findIndexStorePath(in:)
+
+    func testFindIndexStorePathFindsIndexNoindex() throws {
+        let dataStore = tmpDir.appending("Index.noindex/DataStore")
+        try FileManager.default.createDirectory(atPath: dataStore.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStorePath(in: tmpDir)
+        XCTAssertEqual(result, dataStore)
+    }
+
+    func testFindIndexStorePathFindsLegacyIndex() throws {
+        let dataStore = tmpDir.appending("Index/DataStore")
+        try FileManager.default.createDirectory(atPath: dataStore.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStorePath(in: tmpDir)
+        XCTAssertEqual(result, dataStore)
+    }
+
+    func testFindIndexStorePathPrefersIndexNoindex() throws {
+        let noindex = tmpDir.appending("Index.noindex/DataStore")
+        let legacy = tmpDir.appending("Index/DataStore")
+        try FileManager.default.createDirectory(atPath: noindex.string, withIntermediateDirectories: true)
+        try FileManager.default.createDirectory(atPath: legacy.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStorePath(in: tmpDir)
+        XCTAssertEqual(result, noindex)
+    }
+
+    func testFindIndexStorePathReturnsNilWhenNoneExist() {
+        let result = xcodebuild.findIndexStorePath(in: tmpDir)
+        XCTAssertNil(result)
+    }
+
+    // MARK: - findIndexStoreInDerivedData(projectName:derivedDataRoot:)
+
+    func testFindIndexStoreInDerivedDataFindsMatchingProject() throws {
+        let projectDir = tmpDir.appending("MyProject-abc123")
+        let dataStore = projectDir.appending("Index.noindex/DataStore")
+        try FileManager.default.createDirectory(atPath: dataStore.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: tmpDir)
+        XCTAssertEqual(result, dataStore)
+    }
+
+    func testFindIndexStoreInDerivedDataReturnsNilForNonMatchingProject() throws {
+        let projectDir = tmpDir.appending("OtherProject-abc123")
+        let dataStore = projectDir.appending("Index.noindex/DataStore")
+        try FileManager.default.createDirectory(atPath: dataStore.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: tmpDir)
+        XCTAssertNil(result)
+    }
+
+    func testFindIndexStoreInDerivedDataReturnsNilWhenRootDoesNotExist() {
+        let nonexistent = tmpDir.appending("nonexistent")
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: nonexistent)
+        XCTAssertNil(result)
+    }
+
+    func testFindIndexStoreInDerivedDataReturnsNilWhenNoIndexStore() throws {
+        let projectDir = tmpDir.appending("MyProject-abc123")
+        try FileManager.default.createDirectory(atPath: projectDir.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: tmpDir)
+        XCTAssertNil(result)
+    }
+
+    func testFindIndexStoreInDerivedDataPrefersMostRecentlyModified() throws {
+        let fm = FileManager.default
+
+        // Create an older project directory with a valid index store
+        let olderDir = tmpDir.appending("MyProject-older111")
+        let olderDataStore = olderDir.appending("Index.noindex/DataStore")
+        try fm.createDirectory(atPath: olderDataStore.string, withIntermediateDirectories: true)
+
+        // Set its modification date to the past
+        try fm.setAttributes(
+            [.modificationDate: Date.distantPast],
+            ofItemAtPath: olderDir.string
+        )
+
+        // Create a newer project directory with a valid index store
+        let newerDir = tmpDir.appending("MyProject-newer222")
+        let newerDataStore = newerDir.appending("Index.noindex/DataStore")
+        try fm.createDirectory(atPath: newerDataStore.string, withIntermediateDirectories: true)
+
+        // Set its modification date to now
+        try fm.setAttributes(
+            [.modificationDate: Date()],
+            ofItemAtPath: newerDir.string
+        )
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: tmpDir)
+        XCTAssertEqual(result, newerDataStore)
+    }
+
+    func testFindIndexStoreInDerivedDataDoesNotMatchExactName() throws {
+        // A directory named exactly "MyProject" (no hash suffix) should not match
+        let projectDir = tmpDir.appending("MyProject")
+        let dataStore = projectDir.appending("Index.noindex/DataStore")
+        try FileManager.default.createDirectory(atPath: dataStore.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: tmpDir)
+        XCTAssertNil(result)
+    }
+
+    func testFindIndexStoreInDerivedDataDoesNotMatchPrefix() throws {
+        // "MyProjectExtra-abc123" should not match project name "MyProject"
+        let projectDir = tmpDir.appending("MyProjectExtra-abc123")
+        let dataStore = projectDir.appending("Index.noindex/DataStore")
+        try FileManager.default.createDirectory(atPath: dataStore.string, withIntermediateDirectories: true)
+
+        let result = xcodebuild.findIndexStoreInDerivedData(projectName: "MyProject", derivedDataRoot: tmpDir)
+        XCTAssertNil(result)
+    }
+}