fix read-line test / closes #314

Author: Sobeston

website/versioned_docs/version-0.15.x/02-standard-library/04-readers-and-writers.mdx

@@ -23,7 +23,7 @@ will return `error.StreamTooLong`.
 
 A common usecase for readers is to read until the next line (e.g. for user
 input). Here we will do this with the
-[`std.io.getStdIn()`](https://ziglang.org/documentation/master/std/#std.io.getStdIn)
+[`std.fs.File.stdin()`](https://ziglang.org/documentation/0.15.2/std/#std.fs.File.stdin)
 file.
 
 {/* Code snippet not tested as it uses stdin/stdout */}
@@ -34,33 +34,22 @@ const std = @import("std");
 const expect = std.testing.expect;
 const eql = std.mem.eql;
 // hide-end
+test "read until next line" {
+    var stdout_buf: [1024]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buf);
+    const stdout: *std.io.Writer = &stdout_writer.interface;
 
-fn nextLine(reader: anytype, buffer: []u8) !?[]const u8 {
-    var line = (try reader.readUntilDelimiterOrEof(
-        buffer,
-        '\n',
-    )) orelse return null;
-    // trim annoying windows-only carriage return character
-    if (@import("builtin").os.tag == .windows) {
-        return std.mem.trimRight(u8, line, "\r");
-    } else {
-        return line;
-    }
-}
+    var stdin_buf: [1024]u8 = undefined;
+    var stdin_reader = std.fs.File.stdin().reader(&stdin_buf);
+    const stdin: *std.io.Reader = &stdin_reader.interface;
 
-test "read until next line" {
-    const stdout = std.io.getStdOut();
-    const stdin = std.io.getStdIn();
+    try stdout.writeAll("Enter your name\n");
+    try stdout.flush();
 
-    try stdout.writeAll(
-        \\ Enter your name:
-    );
+    const bare_line = try stdin.takeDelimiter('\n') orelse unreachable;
+    const line = std.mem.trim(u8, bare_line, "\r");
 
-    var buffer: [100]u8 = undefined;
-    const input = (try nextLine(stdin.reader(), &buffer)).?;
-    try stdout.writer().print(
-        "Your name is: \"{s}\"\n",
-        .{input},
-    );
+    try stdout.print("Your name is: \"{s}\"\n", .{line});
+    try stdout.flush();
 }
 ```