Narrow StringOutput.OutputType to non-optional

README.md

@@ -140,8 +140,8 @@ let result = try await run(
     return lineCount
 }
 
-print(result.closureResult)         // The line count returned from the closure.
-print(result.standardError ?? "")   // The captured standard error.
+print(result.closureResult) // The line count returned from the closure.
+print(result.standardError) // The captured standard error.
 ```
 
 Stream both standard output and standard error, writing to standard input from the same closure:

Sources/Subprocess/IO/Output.swift

@@ -109,10 +109,10 @@ public struct FileDescriptorOutput: OutputProtocol, ErrorOutputProtocol {
 
 /// An output type that collects the subprocess's output as decoded text using the given encoding.
 public struct StringOutput<Encoding: Unicode.Encoding>: OutputProtocol, ErrorOutputProtocol {
-    public typealias OutputType = String?
+    public typealias OutputType = String
     public let maxSize: Int
 
-    public func output(from span: RawSpan) throws -> String? {
+    public func output(from span: RawSpan) throws -> String {
         span.withUnsafeBytes { ptr in
             let array = Array(ptr)
             return String(decodingBytes: array, as: Encoding.self)

Tests/SubprocessTests/DarwinTests.swift

@@ -65,9 +65,8 @@ struct SubprocessDarwinTests {
             output: .string(limit: .max)
         )
         #expect(pwdResult.terminationStatus.isSuccess)
-        let currentDir = try #require(
-            pwdResult.standardOutput
-        ).trimmingCharacters(in: .whitespacesAndNewlines)
+        let currentDir = pwdResult.standardOutput
+            .trimmingCharacters(in: .whitespacesAndNewlines)
         // On Darwin, /var is linked to /private/var; /tmp is linked /private/tmp
         var expected = FilePath(intendedWorkingDir)
         if expected.starts(with: "/var") || expected.starts(with: "/tmp") {