feat: add support for defining Info.plist files using a variable

Sources/XcodeGraph/Models/Plist.swift

@@ -103,6 +103,9 @@ public enum InfoPlist: Equatable, Codable, Sendable {
     // User defined dictionary of keys/values for an info.plist file.
     case dictionary([String: Plist.Value], configuration: BuildConfiguration? = nil)
 
+    // A user defined xcconfig variable map to .entitlements file
+    case variable(String, configuration: BuildConfiguration? = nil)
+
     // User defined dictionary of keys/values for an info.plist file extending the default set of keys/values
     // for the target type.
     case extendingDefault(with: [String: Plist.Value], configuration: BuildConfiguration? = nil)
@@ -123,7 +126,12 @@ public enum InfoPlist: Equatable, Codable, Sendable {
 
 extension InfoPlist: ExpressibleByStringLiteral {
     public init(stringLiteral value: String) {
-        self = .file(path: try! AbsolutePath(validating: value)) // swiftlint:disable:this force_try
+        let regexPattern = #"^\$\((.+)\)|^\$\{(.+)\}"#
+        if let _ = value.range(of: regexPattern, options: .regularExpression) {
+            self = .variable(value)
+        } else {
+            self = .file(path: try! AbsolutePath(validating: value)) // swiftlint:disable:this force_try
+        }
     }
 }
 

Tests/XcodeGraphTests/Models/InfoPlistTests.swift

@@ -41,4 +41,14 @@ final class InfoPlistTests: XCTestCase {
         // Then
         XCTAssertEqual(subject.path, try AbsolutePath(validating: "/path/Info.list"))
     }
+
+    func test_expressive_by_string_literal_using_build_variable() {
+        // Given
+        let subject1: InfoPlist = "$(CONFIGURATION)/Info.list"
+        let subject2: InfoPlist = "${CONFIGURATION}/Info.list"
+
+        // Then
+        XCTAssertEqual(subject1, .variable("$(CONFIGURATION)/Info.list", configuration: nil))
+        XCTAssertEqual(subject2, .variable("${CONFIGURATION}/Info.list", configuration: nil))
+    }
 }