Merge #2072

2072: Fix YAML's default_value_if handling r=pksunkara a=bkaestner



Co-authored-by: Benjamin Kästner <benjamin.kaestner@gmail.com>

src/build/macros.rs

@@ -65,7 +65,7 @@ macro_rules! yaml_vec_or_str {
 #[cfg(feature = "yaml")]
 macro_rules! yaml_opt_str {
     ($v:expr) => {{
-        if $v.is_null() {
+        if !$v.is_null() {
             Some(
                 $v.as_str()
                     .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v)),

tests/fixtures/app.yaml

@@ -21,7 +21,7 @@ args:
         about: tests positionals with exclusions
         index: 2
         default_value_if:
-            - [flag, Null, some]
+            - [flag, null, some]
             - [positional, other, something]
     - flag:
         short: f

tests/yaml.rs

@@ -54,3 +54,48 @@ fn value_hint() {
         .unwrap();
     assert_eq!(arg.get_value_hint(), ValueHint::FilePath);
 }
+
+#[test]
+fn default_value_if_not_triggered_by_argument() {
+    let yml = load_yaml!("fixtures/app.yaml");
+    let app = App::from(yml);
+
+    // Fixtures use "other" as value
+    let matches = app.try_get_matches_from(vec!["prog", "wrong"]).unwrap();
+
+    assert!(matches.value_of("positional2").is_none());
+}
+
+#[test]
+fn default_value_if_triggered_by_matching_argument() {
+    let yml = load_yaml!("fixtures/app.yaml");
+    let app = App::from(yml);
+
+    let matches = app.try_get_matches_from(vec!["prog", "other"]).unwrap();
+    assert_eq!(matches.value_of("positional2").unwrap(), "something");
+}
+
+#[test]
+fn default_value_if_triggered_by_flag() {
+    let yml = load_yaml!("fixtures/app.yaml");
+    let app = App::from(yml);
+
+    let matches = app
+        .try_get_matches_from(vec!["prog", "--flag", "flagvalue"])
+        .unwrap();
+
+    assert_eq!(matches.value_of("positional2").unwrap(), "some");
+}
+
+#[test]
+fn default_value_if_triggered_by_flag_and_argument() {
+    let yml = load_yaml!("fixtures/app.yaml");
+    let app = App::from(yml);
+
+    let matches = app
+        .try_get_matches_from(vec!["prog", "--flag", "flagvalue", "other"])
+        .unwrap();
+
+    // First condition triggers, therefore "some"
+    assert_eq!(matches.value_of("positional2").unwrap(), "some");
+}