test:zig

guide/language/runtime-safety.zig

@@ -0,0 +1,36 @@
+// Zig provides a level of safety, where problems may be found during execution.
+// Safety can be left on, or turned off.
+// Zig has many cases of so-called `detectable illegal behaviour`,
+// meaning that illegal behaviour will be caught (causing a panic) with safety on,
+// but will result in undefined behaviour with safety off.
+// Users are strongly recommended to develop and test their software with safety on, despite its speed penalties.
+
+// For example, runtime safety protects you from out of bounds indices.
+
+test "out of bounds" {
+    const a = [3]u8{ 1, 2, 3 };
+    var index: u8 = 5;
+    const b = a[index];
+
+    _ = b;
+    index = index;
+}
+
+// test "out of bounds"...index out of bounds
+// .\tests.zig:43:14: 0x7ff698cc1b82 in test "out of bounds" (test.obj)
+//    const b = a[index];
+//             ^
+
+// The user may disable runtime safety for the current block using the built-in function `@setRuntimeSafety`.
+test "out of bounds, no safety" {
+    @setRuntimeSafety(true);
+    // defer @setRuntimeSafety(false);
+    const a = [3]u8{ 1, 2, 3 };
+    var index: u8 = 5;
+    const b = a[index]; // no panic
+
+    _ = b;
+    index = index; // no panic
+}
+
+// Safety is off for some build modes (to be discussed later).