Add some tests to test utf16_to_utf8 and wstring_to_utf8

core/sys/win32/tests/general.odin

@@ -0,0 +1,44 @@
+package win32_tests
+
+import "core:fmt"
+import "core:sys/win32"
+
+main :: proc(){
+    test_utf16_to_utf8 :: proc(str: []u16, comparison: string, expected_result: bool, loc := #caller_location) {
+        result := win32.utf16_to_utf8(str[:]);
+        fmt.assertf((result == comparison) == expected_result, 
+                    "Incorrect utf16_to_utf8 conversion: %q %s %q\nloc = %#v\n", 
+                    result, "!=" if expected_result else "==", comparison, loc);
+    }
+
+    test_utf16_to_utf8([]u16{}, "", true); 
+    test_utf16_to_utf8([]u16{0}, "", true); 
+    test_utf16_to_utf8([]u16{0, 't', 'e', 's', 't'}, "", true); 
+    test_utf16_to_utf8([]u16{0, 't', 'e', 's', 't', 0}, "", true); 
+    test_utf16_to_utf8([]u16{'t', 'e', 's', 't'}, "test", true); 
+    test_utf16_to_utf8([]u16{'t', 'e', 's', 't', 0}, "test", true); 
+    test_utf16_to_utf8([]u16{'t', 'e', 0, 's', 't'}, "te", true); 
+    test_utf16_to_utf8([]u16{'t', 'e', 0, 's', 't', 0}, "te", true); 
+
+    test_wstring_to_utf8 :: proc(str: []u16, comparison: string, expected_result: bool, loc := #caller_location) {
+        result := win32.wstring_to_utf8(nil if len(str) == 0 else cast(win32.Wstring)&str[0], -1);
+        fmt.assertf((result == comparison) == expected_result, 
+                    "Incorrect wstring_to_utf8 conversion: %q %s %q\nloc = %#v\n", 
+                    result, "!=" if expected_result else "==", comparison, loc);
+    }
+
+    test_wstring_to_utf8([]u16{}, "", true); 
+    test_wstring_to_utf8([]u16{0}, "", true); 
+    test_wstring_to_utf8([]u16{0, 't', 'e', 's', 't'}, "", true); 
+    test_wstring_to_utf8([]u16{0, 't', 'e', 's', 't', 0}, "", true); 
+    test_wstring_to_utf8([]u16{'t', 'e', 's', 't', 0}, "test", true); 
+    test_wstring_to_utf8([]u16{'t', 'e', 0, 's', 't'}, "te", true); 
+    test_wstring_to_utf8([]u16{'t', 'e', 0, 's', 't', 0}, "te", true); 
+
+    // WARNING: Passing a non-zero-terminated string to wstring_to_utf8 is dangerous, 
+    //          as it will go out of bounds looking for a zero. 
+    //          It will "fail" or "succeed" by having a zero just after the end of the input string or not.
+    test_wstring_to_utf8([]u16{'t', 'e', 's', 't'}, "test", false); 
+    test_wstring_to_utf8([]u16{'t', 'e', 's', 't', 0}[:4], "test", true); 
+    test_wstring_to_utf8([]u16{'t', 'e', 's', 't', 'q'}[:4], "test", false); 
+}