[gjs: 2/3] testRegress: Verify that undefined can be passed to C functions

[Philip Chimento <pchimento src gnome org>]

commit 255af607ec3dc3e3d7e20738a775800fc50e5b30
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Mon Mar 8 22:01:26 2021 +0100

    testRegress: Verify that undefined can be passed to C functions
    
    When a C function takes integer values an undefined argument should be
    handled as 0, as expected in JS, if instead the function takes a
    floating point value the function value is set to NaN.
    
    Add tests to ensure we handle undefined in function calls as expected.
    
    Fixes: #379

 gi/js-value-inl.h                 |  7 +++++++
 installed-tests/js/testRegress.js | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)
---
diff --git a/gi/js-value-inl.h b/gi/js-value-inl.h
index da1d5135..7a73b72e 100644
--- a/gi/js-value-inl.h
+++ b/gi/js-value-inl.h
@@ -197,6 +197,13 @@ GJS_JSAPI_RETURN_CONVENTION inline bool js_value_to_c_checked(
     if constexpr (std::is_same_v<WantedType, T>)
         return js_value_to_c(cx, value, out);
 
+    if constexpr (std::is_integral_v<WantedType>) {
+        if (value.isUndefined()) {
+            *out = 0;
+            return true;
+        }
+    }
+
     if constexpr (std::is_arithmetic_v<T>) {
         bool ret = js_value_to_c(cx, value, out);
         if (out_of_range) {
diff --git a/installed-tests/js/testRegress.js b/installed-tests/js/testRegress.js
index 56296d94..f067f1a1 100644
--- a/installed-tests/js/testRegress.js
+++ b/installed-tests/js/testRegress.js
@@ -28,10 +28,13 @@ describe('Life, the Universe and Everything', function () {
             const method = `test_int${bits}`;
             expect(Regress[method](42)).toBe(42);
             expect(Regress[method](-42)).toBe(-42);
+            expect(Regress[method](undefined)).toBe(0);
         });
 
         it(`includes unsigned ${bits}-bit integers`, function () {
-            expect(Regress[`test_uint${bits}`](42)).toBe(42);
+            const method = `test_uint${bits}`;
+            expect(Regress[method](42)).toBe(42);
+            expect(Regress[method](undefined)).toBe(0);
         });
     });
 
@@ -40,12 +43,19 @@ describe('Life, the Universe and Everything', function () {
             const method = `test_${type}`;
             expect(Regress[method](42)).toBe(42);
             expect(Regress[method](-42)).toBe(-42);
+
+            if (['float', 'double'].includes(type))
+                expect(Number.isNaN(Regress[method](undefined))).toBeTruthy();
+            else
+                expect(Regress[method](undefined)).toBe(0);
         });
     });
 
     ['ushort', 'uint', 'ulong', 'size'].forEach(type => {
         it(`includes ${type}s`, function () {
-            expect(Regress[`test_${type}`](42)).toBe(42);
+            const method = `test_${type}`;
+            expect(Regress[method](42)).toBe(42);
+            expect(Regress[method](undefined)).toBe(0);
         });
     });