1 files changed, 33 insertions, 0 deletions
diff --git a/src/err.rs b/src/err.rs
new file mode 100644
index 0000000..6a224a1
--- /dev/null
+++ b/src/err.rs
@@ -0,0 +1,33 @@
+use serde_yaml;
+use thiserror::Error;
+
+/// Errors that can be returned for roadmaps.
+#[derive(Error, Debug)]
+pub enum RoadmapError {
+    #[error("roadmap has no goals, must have exactly one")]
+    NoGoals,
+
+    #[error("too many goals, must have exactly one: found {count:}: {}", .names.join(", "))]
+    ManyGoals {
+        count: usize,
+        names: Vec<String>,
+    },
+
+    #[error("step {name:} depends on missing {missing:}")]
+    MissingDep {
+        name: String,
+        missing: String,
+    },
+
+    #[error("step is not a mapping")]
+    StepNotMapping,
+
+    #[error("'depends' must be a list of step names")]
+    DependsNotNames,
+
+    #[error("unknown status: {0}")]
+    UnknownStatus(String),
+
+    #[error(transparent)]
+    SerdeError(#[from] serde_yaml::Error),
+}