add tests

examples/src/01-01.zig

@@ -1,20 +1,27 @@
 const std = @import("std");
 const fs = std.fs;
 const print = std.debug.print;
+const expectEqualStrings = std.testing.expectEqualStrings;
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
-    const file = try fs.cwd().openFile("build.zig", .{});
+    const file = try fs.cwd().openFile("tests/hello-world.txt", .{});
     defer file.close();
 
     const rdr = file.reader();
     var line_no: usize = 0;
+    const expected = [_][]const u8{
+        "Hello Zig. 😁",
+        "",
+        "I love Zig very much!",
+    };
     while (try rdr.readUntilDelimiterOrEofAlloc(allocator, '\n', 4096)) |line| {
         defer allocator.free(line);
 
+        try expectEqualStrings(expected[line_no], line);
         line_no += 1;
         print("{d}--{s}\n", .{ line_no, line });
     }

examples/src/02-01.zig

@@ -22,7 +22,7 @@ pub fn main() !void {
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
-    const file = try fs.cwd().openFile("build.zig", .{});
+    const file = try fs.cwd().openFile("tests/hello-world.txt", .{});
     defer file.close();
 
     const digest = try sha256_digest(allocator, file);

examples/tests/hello-world.txt

@@ -0,0 +1,3 @@
+Hello Zig. 😁
+
+I love Zig very much!