Fix windows test (#16321)

[test_windows_full]

Author: dwijnand

compiler/test/dotty/tools/dotc/TupleShowTests.scala

@@ -4,6 +4,7 @@ package dotc
 import core.*, Decorators.*, Symbols.*
 import printing.Texts.*
 
+import java.lang.System.{ lineSeparator => EOL }
 import org.junit.Test
 
 class TupleShowTests extends DottyTest:
@@ -51,22 +52,27 @@ class TupleShowTests extends DottyTest:
     ))
     chkEq(exp, obt)
 
-  @Test def tup3_show10 = chkEq("(Int,\n  Long,\n  Short)", tup3.toText(ctx.printer).mkString(10, false))
+  @Test def tup3_show10 = chkEq("(Int,\n  Long,\n  Short)".normEOL, tup3.toText(ctx.printer).mkString(10, false))
 
   val res21 = """|(Int, Int, Int, Int, Int, Long, Long, Long, Long, Long, Int, Int, Int, Int,
-                 |  Int, Long, Long, Long, Long, Long, Int)""".stripMargin
+                 |  Int, Long, Long, Long, Long, Long, Int)""".stripMargin.normEOL
 
   val res22 = """|(Int, Int, Int, Int, Int, Long, Long, Long, Long, Long, Int, Int, Int, Int,
-                 |  Int, Long, Long, Long, Long, Long, Int, Long)""".stripMargin
+                 |  Int, Long, Long, Long, Long, Long, Int, Long)""".stripMargin.normEOL
 
   val res23 = """|(Int, Int, Int, Int, Int, Long, Long, Long, Long, Long, Int, Int, Int, Int,
-                 |  Int, Long, Long, Long, Long, Long, Int, Long, Short)""".stripMargin
+                 |  Int, Long, Long, Long, Long, Long, Int, Long, Short)""".stripMargin.normEOL
 
   val res24 = """|(Int, Int, Int, Int, Int, Long, Long, Long, Long, Long, Int, Int, Int, Int,
-                 |  Int, Long, Long, Long, Long, Long, Int, Long, Short, Short)""".stripMargin
+                 |  Int, Long, Long, Long, Long, Long, Int, Long, Short, Short)""".stripMargin.normEOL
 
   def chkEq[A](expected: A, obtained: A) = assert(expected == obtained, diff(s"$expected", s"$obtained"))
 
+  /** On Windows the string literal in this test source file will be read with `\n` (b/c of "-encoding UTF8")
+  *   but the compiler will correctly emit \r\n as the line separator.
+  *   So we align the expected result to faithfully compare test results. */
+  extension (str: String) def normEOL = if EOL == "\n" then str else str.replace("\n", EOL).nn
+
   def diff(exp: String, obt: String) =
     val min = math.min(exp.length, obt.length)
     val pre =