#42 Error if args but no cases

Author: la10736

playground/src/main.rs

@@ -1,20 +1,4 @@
 use rstest::*;
 
-#[fixture]
-fn first() -> u32 {
-    42
-}
-
-#[fixture]
-fn second() -> &'static str {
-    "foo"
-}
-
-#[fixture]
-fn double(first: u32, second: &str) -> u32 {
-    0
-}
-
-
-#[rstest(double("pippo"))]
-fn should_show_type_error(double: u32) {}
+#[rstest(one, two, three)]
+fn should_show_error_for_no_case(one: u32, two: u32, three: u32) {}

resources/rstest/args_with_no_cases.rs

@@ -0,0 +1,4 @@
+use rstest::rstest;
+
+#[rstest(one, two, three)]
+fn should_show_error_for_no_case(one: u32, two: u32, three: u32) {}

src/lib.rs

@@ -569,10 +569,10 @@ pub fn rstest(args: proc_macro::TokenStream,
     let errors = errors_in_rstest(&test, &info);
 
     if errors.is_empty() {
-        if info.data.cases().next().is_none() {
-            render_single_case(test, info)
-        } else {
+        if info.data.has_cases() {
             render_parametrize_cases(test, info)
+        } else {
+            render_single_case(test, info)
         }
     } else {
         errors
@@ -640,6 +640,17 @@ fn invalid_case_errors(params: &RsTestData) -> Errors {
     )
 }
 
+fn case_args_without_cases(params: &RsTestData) -> Errors {
+    if !params.has_cases() {
+        return Box::new(params.case_args().map(|a|
+                syn::Error::new(a.span(), "No cases for this argument."))
+        );
+    }
+    Box::new(
+        std::iter::empty()
+    )
+}
+
 fn errors_in_parametrize(test: &ItemFn, info: &RsTestInfo) -> TokenStream {
     missed_arguments_errors(test, info.data.case_args())
         .chain(missed_arguments_errors(test, info.data.fixtures()))
@@ -661,6 +672,7 @@ fn errors_in_rstest(test: &ItemFn, info: &parse::rstest::RsTestInfo) -> TokenStr
     missed_arguments_errors(test, info.data.items.iter())
         .chain(duplicate_arguments_errors(info.data.items.iter()))
         .chain(invalid_case_errors(&info.data))
+        .chain(case_args_without_cases(&info.data))
         .map(|e| e.to_compile_error())
         .collect()
 }

src/parse/rstest.rs

@@ -47,6 +47,11 @@ impl RsTestData {
             )
     }
 
+    #[allow(dead_code)]
+    pub(crate) fn has_case_args(&self) -> bool {
+        self.case_args().next().is_some()
+    }
+
     pub(crate) fn cases(&self) -> impl Iterator<Item=&TestCase> {
         self.items.iter()
             .filter_map(|it|
@@ -57,6 +62,10 @@ impl RsTestData {
             )
     }
 
+    pub(crate) fn has_cases(&self) -> bool {
+        self.cases().next().is_some()
+    }
+
     pub(crate) fn fixtures(&self) -> impl Iterator<Item=&Fixture> {
         self.items.iter().filter_map(|it|
             match it {
@@ -65,6 +74,11 @@ impl RsTestData {
             }
         )
     }
+
+    #[allow(dead_code)]
+    pub(crate) fn has_fixtures(&self) -> bool {
+        self.fixtures().next().is_some()
+    }
 }
 
 impl Parse for RsTestData {

tests/rstest/mod.rs

@@ -232,6 +232,48 @@ mod cases {
         }
     }
 
+    mod not_compile_if_args_but_no_cases {
+        use super::*;
+
+        use lazy_static::lazy_static;
+        use std::process::Output;
+
+        //noinspection RsTypeCheck
+        fn execute() -> &'static (Output, String) {
+            lazy_static! {
+                static ref OUTPUT: (Output, String) =
+                    run_test("args_with_no_cases.rs");
+            }
+            assert_ne!(Some(0), OUTPUT.0.status.code(), "Should not compile");
+            &OUTPUT
+        }
+
+        #[test]
+        fn report_error() {
+            let (output, name) = execute();
+            let stderr = output.stderr.str();
+
+            assert_in!(stderr, format!("
+                error: No cases for this argument.
+                 --> {}/src/lib.rs:3:10
+                  |
+                3 | #[rstest(one, two, three)]
+                  |          ^^^
+                ", name).unindent());
+
+        }
+
+        #[test]
+        fn and_reports_all_errors() {
+            let (output, _) = execute();
+            let stderr = output.stderr.str();
+
+            // Exactly 3 cases are wrong
+            assert_eq!(3, stderr.count("No cases for this argument."),
+                       "Should contain message exactly 3 occurrences in error message:\n{}", stderr);
+        }
+    }
+
     mod dump_input_values {
         use super::*;