Fallback to the latest major.minor on select

Sources/XcodesKit/Models+FirstWithVersion.swift

@@ -41,7 +41,28 @@ public extension Array where Element == InstalledXcode {
     /// If there are multiple matches, or no matches, nil is returned.
     func first(withVersion version: Version) -> InstalledXcode? {
         findXcode(version: version, in: self, versionKeyPath: \.version)
-    } 
+    }
+
+    /// Returns the newest InstalledXcode that shares the requested major and minor versions when:
+    ///   - No prerelease or build metadata identifiers were specified.
+    ///   - The requested patch version is 0 (i.e. not explicitly provided).
+    ///   - An exact match via `first(withVersion:)` could not be found.
+    /// Prefers release builds when available, otherwise falls back to prerelease builds.
+    func latestMatchingMajorMinorVersion(withVersion version: Version) -> InstalledXcode? {
+        let matchingVersions = filter {
+            $0.version.major == version.major &&
+            $0.version.minor == version.minor
+        }
+
+        if matchingVersions.isEmpty {
+            return nil
+        }
+
+        let releaseVersions = matchingVersions.filter { $0.version.prereleaseIdentifiers.isEmpty }
+        let candidates = releaseVersions.isEmpty ? matchingVersions : releaseVersions
+
+        return candidates.max(by: { $0.version < $1.version })
+    }
 }
 
 extension Version {

Sources/XcodesKit/XcodeSelect.swift

@@ -24,16 +24,27 @@ public func selectXcode(shouldPrint: Bool, pathOrVersion: String, directory: Pat
 
         let versionToSelect = pathOrVersion.isEmpty ? Version.fromXcodeVersionFile() : Version(xcodeVersion: pathOrVersion)
         let installedXcodes = Current.files.installedXcodes(directory)
-        if let version = versionToSelect,
-           let installedXcode = installedXcodes.first(withVersion: version) {
+        if let version = versionToSelect {
             let selectedInstalledXcodeVersion = installedXcodes.first { output.out.hasPrefix($0.path.string) }.map { $0.version }
-            if installedXcode.version == selectedInstalledXcodeVersion {
+            if version == selectedInstalledXcodeVersion {
                 Current.logging.log("Xcode \(version) is already selected".green)
                 Current.shell.exit(0)
                 return Promise.value(())
             }
 
-            return selectXcodeAtPath(installedXcode.path.string)
+            var xcodeToSelect = installedXcodes.first(withVersion: version)
+            if xcodeToSelect == nil, let fallbackInstalledXcode = installedXcodes.latestMatchingMajorMinorVersion(withVersion: version) {
+                Current.logging.log("Xcode \(version) is not installed. Selecting \(fallbackInstalledXcode.version) instead.".green)
+                xcodeToSelect = fallbackInstalledXcode
+            }
+
+            guard let selectedXcode = xcodeToSelect else {
+                Current.logging.log("Xcode \(version) is not installed".red)
+                Current.shell.exit(1)
+                return Promise.value(())
+            }
+
+            return selectXcodeAtPath(selectedXcode.path.string)
                 .done { output in
                     Current.logging.log("Selected \(output.out)".green)
                     Current.shell.exit(0)

Tests/XcodesKitTests/XcodesKitTests.swift

@@ -1169,6 +1169,38 @@ final class XcodesKitTests: XCTestCase {
 
         """)
     }
+
+    func test_SelectFallsBackToLatestPatchVersion() {
+        var log = ""
+        XcodesKit.Current.logging.log = { log.append($0 + "\n") }
+
+        let fallbackXcode = InstalledXcode(path: Path("/Applications/Xcode-2.0.1.app")!, version: Version(2, 0, 1))
+        Current.files.installedXcodes = { _ in [fallbackXcode] }
+
+        var xcodeSelectPrintPathCallCount = 0
+        Current.shell.xcodeSelectPrintPath = {
+            defer { xcodeSelectPrintPathCallCount += 1 }
+            if xcodeSelectPrintPathCallCount == 0 {
+                return Promise.value((status: 0, out: "/Applications/Xcode-1.0.0.app/Contents/Developer", err: ""))
+            } else {
+                return Promise.value((status: 0, out: "\(fallbackXcode.path.string)/Contents/Developer", err: ""))
+            }
+        }
+
+        Current.shell.xcodeSelectSwitch = { _, path in
+            XCTAssertEqual(path, fallbackXcode.path.string)
+            return Promise.value((status: 0, out: "", err: ""))
+        }
+
+        selectXcode(shouldPrint: false, pathOrVersion: "2.0", directory: Path.root.join("Applications"))
+            .cauterize()
+
+        XCTAssertEqual(log, """
+        Xcode 2.0 is not installed. Selecting 2.0.1 instead.
+        Selected /Applications/Xcode-2.0.1.app/Contents/Developer
+
+        """)
+    }
 
     func test_Installed_InteractiveTerminal() {
         var log = ""