unix: small fixes for TestPipe

Check error returned by Pipe, use %v to format error values and strip
trailing newlines from Errorf messages. Also move TestPipe above the
test helper functions.

Change-Id: Id431c8ffbcf525347cb4c138df69f92cc730f54a
Reviewed-on: https://go-review.googlesource.com/c/sys/+/283592
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/syscall_unix_test.go

@@ -782,6 +782,48 @@ func TestMkdev(t *testing.T) {
 	}
 }
 
+func TestPipe(t *testing.T) {
+	const s = "hello"
+	var pipes [2]int
+	err := unix.Pipe(pipes[:])
+	if err != nil {
+		t.Fatalf("pipe: %v", err)
+	}
+	r := pipes[0]
+	w := pipes[1]
+	go func() {
+		n, err := unix.Write(w, []byte(s))
+		if err != nil {
+			t.Errorf("bad write: %v", err)
+			return
+		}
+		if n != len(s) {
+			t.Errorf("bad write count: %d", n)
+			return
+		}
+		err = unix.Close(w)
+		if err != nil {
+			t.Errorf("bad close: %v", err)
+			return
+		}
+	}()
+	var buf [10 + len(s)]byte
+	n, err := unix.Read(r, buf[:])
+	if err != nil {
+		t.Fatalf("bad read: %v", err)
+	}
+	if n != len(s) {
+		t.Fatalf("bad read count: %d", n)
+	}
+	if string(buf[:n]) != s {
+		t.Fatalf("bad contents: %s", string(buf[:n]))
+	}
+	err = unix.Close(r)
+	if err != nil {
+		t.Fatalf("bad close: %v", err)
+	}
+}
+
 func TestRenameat(t *testing.T) {
 	defer chtmpdir(t)()
 
@@ -896,42 +938,3 @@ func chtmpdir(t *testing.T) func() {
 		os.RemoveAll(d)
 	}
 }
-
-func TestPipe(t *testing.T) {
-	const s = "hello"
-	var pipes [2]int
-	unix.Pipe(pipes[:])
-	r := pipes[0]
-	w := pipes[1]
-	go func() {
-		n, err := unix.Write(w, []byte(s))
-		if err != nil {
-			t.Errorf("bad write: %s\n", err)
-			return
-		}
-		if n != len(s) {
-			t.Errorf("bad write count: %d\n", n)
-			return
-		}
-		err = unix.Close(w)
-		if err != nil {
-			t.Errorf("bad close: %s\n", err)
-			return
-		}
-	}()
-	var buf [10 + len(s)]byte
-	n, err := unix.Read(r, buf[:])
-	if err != nil {
-		t.Fatalf("bad read: %s\n", err)
-	}
-	if n != len(s) {
-		t.Fatalf("bad read count: %d\n", n)
-	}
-	if string(buf[:n]) != s {
-		t.Fatalf("bad contents: %s\n", string(buf[:n]))
-	}
-	err = unix.Close(r)
-	if err != nil {
-		t.Fatalf("bad close: %s\n", err)
-	}
-}