1 files changed, 13 insertions, 7 deletions

diff --git a/src/parser.rs b/src/parser.rs
index 8b0dc05..637220c 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -34,7 +34,7 @@ fn step_from_value(name: &str, value: &Value) -> ParseResult<Step> {
             let mut step = Step::new(name, label);
             step.set_status(status);
 
-            for depname in parse_depends(&value).iter() {
+            for depname in parse_depends(&value)?.iter() {
                 step.add_dependency(depname);
             }
 
@@ -45,20 +45,26 @@ fn step_from_value(name: &str, value: &Value) -> ParseResult<Step> {
 }
 
 // Get a sequence of depenencies.
-fn parse_depends(map: &Value) -> Vec<&str> {
+fn parse_depends(map: &Value) -> ParseResult<Vec<&str>> {
     let key_name = "depends";
     let key = Value::String(key_name.to_string());
     let mut depends: Vec<&str> = vec![];
+    let need_list_of_names = format!("'depends' must be a list of step names");
 
-    if let Some(Value::Sequence(deps)) = map.get(&key) {
-        for depname in deps.iter() {
-            if let Value::String(depname) = depname {
-                depends.push(depname);
+    match map.get(&key) {
+        None => (),
+        Some(Value::Sequence(deps)) => {
+            for depname in deps.iter() {
+                match depname {
+                    Value::String(depname) => depends.push(depname),
+                    _ => return Err(need_list_of_names),
+                }
             }
         }
+        _ => return Err(need_list_of_names),
     }
 
-    depends
+    Ok(depends)
 }
 
 // Get label string from a Mapping element, or empty string.