[UtilityTests] Close master fd explicitly

It looks like if deinit wasn't called for pesudoterminal in time the
master won't be closed and OS would assign slave fd to new pipe (because it was already closed)
and that turns out to be a bad file descriptor somehow...
Closing explicitly fixes the issue.

- <rdar://problem/28411803> POSIX.popen() sometimes breaks the build
- https://bugs.swift.org/browse/SR-2703

Author: aciidgh

Tests/UtilityTests/ProgressBarTests.swift

@@ -43,11 +43,11 @@ final class PseudoTerminal {
         return String(cString: buf)
     }
 
-    func close() {
+    func closeSlave() {
         _ = libc.close(slave)
     }
 
-    deinit {
+    func closeMaster() {
         _ = libc.close(master)
     }
 }
@@ -79,9 +79,10 @@ final class ProgressBarTests: XCTestCase {
         }
         thread.start()
         runProgressBar(bar)
-        pty.close()
+        pty.closeSlave()
         // Make sure to read the complete output before checking it.
         thread.join()
+        pty.closeMaster()
         XCTAssertTrue(output.chuzzle()?.hasPrefix("\u{1B}[36m\u{1B}[1mTestHeader\u{1B}[0m") ?? false)
     }
 

Tests/UtilityTests/ShellTests.swift

@@ -16,27 +16,18 @@ import Utility
 class ShellTests: XCTestCase {
 
     func testPopen() {
-        // FIXME: Disabled due to https://bugs.swift.org/browse/SR-2703
-      #if false
         XCTAssertEqual(try! popen(["echo", "foo"]), "foo\n")
-      #endif
     }
 
     func testPopenWithBufferLargerThanThatAllocated() {
-        // FIXME: Disabled due to https://bugs.swift.org/browse/SR-2703
-      #if false
         let path = AbsolutePath(#file).parentDirectory.parentDirectory.appending(components: "GetTests", "VersionGraphTests.swift")
         XCTAssertGreaterThan(try! popen(["cat", path.asString]).characters.count, 4096)
-      #endif
     }
 
     func testPopenWithBinaryOutput() {
-        // FIXME: Disabled due to https://bugs.swift.org/browse/SR-2703
-      #if false
         if (try? popen(["cat", "/bin/cat"])) != nil {
             XCTFail("popen succeeded but should have faileds")
         }
-      #endif
     }
 
     static var allTests = [