Add msg-arg for lang.assert

Rafflesiaceae · May 22, 2022 · 602df4b · 602df4b
1 parent 3234dec
commit 602df4b
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 4 deletions.
diff --git a/lang/assert.go b/lang/assert.go
@@ -11,10 +11,13 @@ func Assert(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple,
 	// @TODO return an AssertionError that also involves a backtrace
 	var err error
 
-	var x, y starlark.Comparable
-	var xfail starlark.Bool
+	var (
+		msg   string
+		x, y  starlark.Comparable
+		xfail starlark.Bool
+	)
 
-	if err := starlark.UnpackArgs("assert", args, kwargs, "x", &x, "y?", &y, "xfail?", &xfail); err != nil {
+	if err := starlark.UnpackArgs("assert", args, kwargs, "x", &x, "y?", &y, "msg?", &msg, "xfail?", &xfail); err != nil {
 		return nil, err
 	}
 
@@ -33,7 +36,11 @@ func Assert(thread *starlark.Thread, fn *starlark.Builtin, args starlark.Tuple,
 	}
 
 	if !truth {
-		return starlark.None, fmt.Errorf("%s != %s", x, y)
+		if msg == "" {
+			return starlark.None, fmt.Errorf("%s != %s", x, y)
+		} else {
+			return starlark.None, fmt.Errorf("%s; %s != %s", msg, x, y)
+		}
 	}
 
 	return starlark.None, nil

diff --git a/quicktest.nosh b/quicktest.nosh
@@ -20,6 +20,9 @@ assert(7+1, 8)
 assert(1, 2, xfail=True)
 assert("neurath")
 assert(not "")
+# test msg-arg
+res = run(os.executable(), "-c", 'assert(False, msg="Neurath")', capture=["stderr"], check=False)
+assert(res.stderr, "Traceback (most recent call last):\n  -c:1:7: in <toplevel>\nError in assert: Neurath; False != True\n")
 
 # TEST starlark features
 ## @XXX f"...{foo}..." formatting strings don't work yet