macro_tools 0.84.0

Tools for writing procedural macroses.
Documentation 
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//! Test for trailing comma issue fix in `generic_params ::decompose`

use macro_tools ::generic_params;
use quote ::quote;
use syn ::parse_quote;

#[ test ]
fn test_trailing_comma_issue_mre() 
{
  // Test case 1 : Simple lifetime parameter
  let generics: syn ::Generics = parse_quote! { < 'a > };
  let (_, impl_gen, ty_gen, _) = generic_params ::decompose(&generics);
  
  // Generate code using the decomposed generics
  let impl_code = quote! { impl< #impl_gen > MyTrait for MyStruct };
  let type_code = quote! { MyStruct< #ty_gen > };
  
  println!("Test 1 - Single lifetime: ");
  println!("  impl_gen: {}", quote! { #impl_gen });
  println!("  ty_gen: {}", quote! { #ty_gen });
  println!("  Generated impl: {impl_code}");
  println!("  Generated type: {type_code}");
  
  // Check if trailing commas exist (they shouldn't)
  assert!(!impl_gen.trailing_punct(), "impl_gen should not have trailing comma");
  assert!(!ty_gen.trailing_punct(), "ty_gen should not have trailing comma");
  
  // Test case 2 : Multiple generic parameters
  let generics: syn ::Generics = parse_quote! { < 'a, T: Clone, const N: usize > };
  let (_, impl_gen, ty_gen, _) = generic_params ::decompose(&generics);
  
  let impl_code = quote! { impl< #impl_gen > MyTrait for MyStruct };
  let type_code = quote! { MyStruct< #ty_gen > };
  
  println!("\nTest 2 - Multiple parameters: ");
  println!("  impl_gen: {}", quote! { #impl_gen });
  println!("  ty_gen: {}", quote! { #ty_gen });
  println!("  Generated impl: {impl_code}");
  println!("  Generated type: {type_code}");
  
  // Check if trailing commas exist (they shouldn't)
  assert!(!impl_gen.trailing_punct(), "impl_gen should not have trailing comma");
  assert!(!ty_gen.trailing_punct(), "ty_gen should not have trailing comma");
  
  // Test case 3 : Empty generics
  let generics: syn ::Generics = parse_quote! { };
  let (_, impl_gen, ty_gen, _) = generic_params ::decompose(&generics);
  
  println!("\nTest 3 - Empty generics: ");
  println!("  impl_gen is empty: {}", impl_gen.is_empty());
  println!("  ty_gen is empty: {}", ty_gen.is_empty());
  
  // Test case 4 : Type parameter only
  let generics: syn ::Generics = parse_quote! { < T > };
  let (_, impl_gen, ty_gen, _) = generic_params ::decompose(&generics);
  
  let impl_code = quote! { impl< #impl_gen > MyTrait for MyStruct };
  let type_code = quote! { MyStruct< #ty_gen > };
  
  println!("\nTest 4 - Single type parameter: ");
  println!("  impl_gen: {}", quote! { #impl_gen });
  println!("  ty_gen: {}", quote! { #ty_gen });
  println!("  Generated impl: {impl_code}");
  println!("  Generated type: {type_code}");
  
  assert!(!impl_gen.trailing_punct(), "impl_gen should not have trailing comma");
  assert!(!ty_gen.trailing_punct(), "ty_gen should not have trailing comma");
}