Chore: Rework examples for thorough extension testing

1 files changed, 41 insertions, 0 deletions

diff --git a/examples/snippets/fibonacci.zig b/examples/snippets/fibonacci.zig
new file mode 100644
index 0000000..327bbd3
--- /dev/null
+++ b/examples/snippets/fibonacci.zig
@@ -0,0 +1,41 @@
+const std = @import("std");
+
+/// Compute the nth Fibonacci number iteratively.
+pub fn fibonacci(n: u64) u64 {
+    if (n <= 1) return n;
+    var a: u64 = 0;
+    var b: u64 = 1;
+    var i: u64 = 2;
+    while (i <= n) : (i += 1) {
+        const next = a + b;
+        a = b;
+        b = next;
+    }
+    return b;
+}
+
+pub fn main(init: std.process.Init) !void {
+    const io = init.io;
+    var buf: [4096]u8 = undefined;
+    var fw: std.Io.File.Writer = .init(.stdout(), io, &buf);
+    defer fw.interface.flush() catch {};
+    const w = &fw.interface;
+
+    try w.print("Fibonacci sequence (first 12 terms):\n", .{});
+    for (0..12) |n| {
+        try w.print("  fib({d}) = {d}\n", .{ n, fibonacci(n) });
+    }
+}
+
+test "fibonacci base cases" {
+    try std.testing.expectEqual(@as(u64, 0), fibonacci(0));
+    try std.testing.expectEqual(@as(u64, 1), fibonacci(1));
+    try std.testing.expectEqual(@as(u64, 1), fibonacci(2));
+}
+
+test "fibonacci sequence" {
+    const expected = [_]u64{ 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 };
+    for (expected, 0..) |v, n| {
+        try std.testing.expectEqual(v, fibonacci(n));
+    }
+}