[Utility] Add SingleLineProgressBar

This progress bar is visually better if the terminal is "dumb".

Author: aciidgh

Diff for: Sources/Commands/SwiftTestTool.swift

@@ -463,7 +463,7 @@ final class ParallelTestRunner {
     init(testPath: AbsolutePath, processSet: ProcessSet) {
         self.testPath = testPath
         self.processSet = processSet
-        progressBar = createProgressBar(forStream: stdoutStream, header: "Tests")
+        progressBar = createProgressBar(forStream: stdoutStream, header: "Testing:")
     }
 
     /// Whether to display output from successful tests.
@@ -539,7 +539,7 @@ final class ParallelTestRunner {
 
         // Wait till all threads finish execution.
         workers.forEach { $0.join() }
-        progressBar.complete()
+        progressBar.complete(success: outputs.failure.isEmpty)
 
         if shouldOutputSuccess {
             printOutput(outputs.success)

Diff for: Sources/Utility/ProgressBar.swift

@@ -13,7 +13,44 @@ import Basic
 /// A protocol to operate on terminal based progress bars.
 public protocol ProgressBarProtocol {
     func update(percent: Int, text: String)
-    func complete()
+    func complete(success: Bool)
+}
+
+/// A single line progress bar.
+public final class SingleLineProgressBar: ProgressBarProtocol {
+    private let header: String
+    private var isClear: Bool
+    private var stream: OutputByteStream
+    private var displayed: Set<Int> = []
+
+    init(stream: OutputByteStream, header: String) {
+        self.stream = stream
+        self.header = header
+        self.isClear = true
+    }
+
+    public func update(percent: Int, text: String) {
+        if isClear {
+            stream <<< header
+            stream <<< "\n"
+            stream.flush()
+            isClear = false
+        }
+
+        let displayPercentage = Int(Double(percent / 10).rounded(.down)) * 10
+        if percent != 100, !displayed.contains(displayPercentage) {
+            stream <<< String(displayPercentage) <<< ".. "
+            displayed.insert(displayPercentage)
+        }
+        stream.flush()
+    }
+
+    public func complete(success: Bool) {
+        if success {
+            stream <<< "OK"
+            stream.flush()
+        }
+    }
 }
 
 /// Simple ProgressBar which shows the update text in new lines.
@@ -41,7 +78,7 @@ public final class SimpleProgressBar: ProgressBarProtocol {
         stream.flush()
     }
 
-    public func complete() {
+    public func complete(success: Bool) {
     }
 }
 
@@ -90,15 +127,27 @@ public final class ProgressBar: ProgressBarProtocol {
         term.moveCursor(up: 1)
     }
 
-    public func complete() {
+    public func complete(success: Bool) {
         term.endLine()
     }
 }
 
 /// Creates colored or simple progress bar based on the provided output stream.
 public func createProgressBar(forStream stream: OutputByteStream, header: String) -> ProgressBarProtocol {
-    if let stdStream = stream as? LocalFileOutputByteStream, let term = TerminalController(stream: stdStream) {
+    guard let stdStream = stream as? LocalFileOutputByteStream else {
+        return SimpleProgressBar(stream: stream, header: header)
+    }
+
+    // If we have a terminal, use animated progress bar.
+    if let term = TerminalController(stream: stdStream) {
         return ProgressBar(term: term, header: header)
     }
+
+    // If the terminal is dumb, use single line progress bar.
+    if TerminalController.terminalType(stdStream) == .dumb {
+        return SingleLineProgressBar(stream: stream, header: header)
+    }
+
+    // Use simple progress bar by default.
     return SimpleProgressBar(stream: stream, header: header)
 }

Diff for: Tests/UtilityTests/ProgressBarTests.swift

@@ -99,7 +99,7 @@ final class ProgressBarTests: XCTestCase {
         for i in 0...5 {
             bar.update(percent: i, text: String(i))
         }
-        bar.complete()
+        bar.complete(success: true)
     }
 
     static var allTests = [