update: adds unit test for EXP and SIGN

base/src/test/test_exp_sign.rs

@@ -0,0 +1,26 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn fn_arguments() {
+    let mut model = new_empty_model();
+    model._set("A1", "=EXP()");
+    model._set("A2", "=SIGN()");
+
+    model._set("A3", "=EXP(0)");
+    model._set("A4", "=SIGN(-10)");
+
+    model._set("A5", "=EXP(1, 2)");
+    model._set("A6", "=SIGN(1, 2)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"#ERROR!");
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+
+    assert_eq!(model._get_text("A3"), *"1");
+    assert_eq!(model._get_text("A4"), *"-1");
+
+    assert_eq!(model._get_text("A5"), *"#ERROR!");
+    assert_eq!(model._get_text("A6"), *"#ERROR!");
+}