Introduce more granular module errors for configuration

libchisel/src/binaryenopt.rs

@@ -40,7 +40,7 @@ impl ModuleConfig for BinaryenOptimiser {
         if let Some(preset) = config.get("preset") {
             BinaryenOptimiser::with_preset(preset)
         } else {
-            Err(ModuleError::NotSupported)
+            Err(ModuleError::MissingConfigKey("preset"))
         }
     }
 }
@@ -55,7 +55,7 @@ impl ModulePreset for BinaryenOptimiser {
             "O4" => Ok(BinaryenOptimiser::O4),
             "Os" => Ok(BinaryenOptimiser::Os),
             "Oz" => Ok(BinaryenOptimiser::Oz),
-            _ => Err(ModuleError::NotSupported),
+            _ => Err(ModuleError::InvalidConfigValue("preset", preset)),
         }
     }
 }

libchisel/src/lib.rs

@@ -33,6 +33,9 @@ pub enum ModuleKind {
 pub enum ModuleError {
     NotSupported,
     NotFound,
+    InvalidConfigKey(String),
+    InvalidConfigValue(String, String),
+    MissingConfigKey(String),
     Custom(String),
 }
 
@@ -110,9 +113,19 @@ impl fmt::Display for ModuleError {
             f,
             "{}",
             match self {
-                ModuleError::NotSupported => "Method unsupported",
-                ModuleError::NotFound => "Not found",
-                ModuleError::Custom(msg) => msg,
+                ModuleError::NotSupported => "Method unsupported".to_string(),
+                ModuleError::NotFound => "Not found".to_string(),
+                ModuleError::InvalidConfigKey(key) => {
+                    format!("Invalid configuration key supplied ({})", key)
+                }
+                ModuleError::InvalidConfigValue(key, value) => format!(
+                    "For the configuration key ({}) invalid value ({}) was supplied",
+                    key, value
+                ),
+                ModuleError::MissingConfigKey(key) => {
+                    format!("Missing required configuration key ({})", key)
+                }
+                ModuleError::Custom(msg) => msg.to_string(),
             }
         )
     }
@@ -123,6 +136,11 @@ impl error::Error for ModuleError {
         match self {
             ModuleError::NotSupported => "Method unsupported",
             ModuleError::NotFound => "Not found",
+            ModuleError::InvalidConfigKey(_) => "Invalid configuration key supplied",
+            ModuleError::InvalidConfigValue(_, _) => {
+                "Invalid value was supplied for the configuration key"
+            }
+            ModuleError::MissingConfigKey(_) => "Missing required configuration key",
             ModuleError::Custom(msg) => msg,
         }
     }

libchisel/src/remapimports.rs

@@ -41,7 +41,7 @@ impl<'a> ModuleConfig for RemapImports<'a> {
         if let Some(preset) = config.get("preset") {
             RemapImports::with_preset(preset)
         } else {
-            Err(ModuleError::NotSupported)
+            Err(ModuleError::MissingConfigKey("preset".to_string()))
         }
     }
 }
@@ -73,7 +73,12 @@ impl<'a> ModulePreset for RemapImports<'a> {
                     ImportList::with_preset("bignum")?,
                     Some("bignum_"),
                 )),
-                _ => return Err(ModuleError::NotSupported),
+                _ => {
+                    return Err(ModuleError::InvalidConfigValue(
+                        "preset".to_string(),
+                        preset_individual.to_string(),
+                    ))
+                }
             }
         }