Update chr to be compatible with CPython

src/runtime/builtin_modules/builtins.cpp

@@ -202,11 +202,12 @@ Box* open(Box* arg1, Box* arg2) {
 
 extern "C" Box* chr(Box* arg) {
     if (arg->cls != int_cls) {
-        fprintf(stderr, "TypeError: coercing to Unicode: need string of buffer, %s found\n", getTypeName(arg)->c_str());
-        raiseExcHelper(TypeError, "");
+        raiseExcHelper(TypeError, "an integer is required");
     }
     i64 n = static_cast<BoxedInt*>(arg)->n;
-    RELEASE_ASSERT(n >= 0 && n < 256, "");
+    if (n < 0 || n >= 256) {
+        raiseExcHelper(ValueError, "chr() arg not in range(256)");
+    }
 
     return boxString(std::string(1, (char)n));
 }

test/tests/test_chr.py

+
+
+assert chr(0) == '\x00'
+assert chr(1) == '\x01'
+assert chr(128) == '\x80'
+assert chr(255) == '\xff'
+
+try:
+    chr('a')
+    assert False
+except TypeError as e:
+    assert e.message == 'an integer is required'
+
+try:
+    chr(256)
+    assert 'chr(256) should throw chr() arg not in range(256)' == False
+except ValueError as e:
+    assert e.message == 'chr() arg not in range(256)'
+
+try:
+    chr(-1)
+    assert 'chr(-1) should throw chr() arg not in range(256)' == False
+except ValueError as e:
+    assert e.message == 'chr() arg not in range(256)'