Add test for duplicated struct

Signed-off-by: Christian Poveda <[email protected]>

Author: pvdrz

cyclonedx-bom-macros/tests/ui/fail/duplicated_struct.rs

@@ -0,0 +1,15 @@
+use cyclonedx_bom_macros::versioned;
+
+#[versioned("1.0", "2.0")]
+mod base {
+    // Define `Foo` for 1.0 twice
+    #[versioned("1.0")]
+    pub struct Foo;
+
+    #[versioned("1.0")]
+    pub struct Foo;
+}
+
+fn main() {
+    let _ = v1_0::Foo;
+}

cyclonedx-bom-macros/tests/ui/fail/duplicated_struct.stderr

@@ -0,0 +1,10 @@
+error[E0428]: the name `Foo` is defined multiple times
+  --> tests/ui/fail/duplicated_struct.rs:10:5
+   |
+7  |     pub struct Foo;
+   |     --------------- previous definition of the type `Foo` here
+...
+10 |     pub struct Foo;
+   |     ^^^^^^^^^^^^^^^ `Foo` redefined here
+   |
+   = note: `Foo` must be defined only once in the type namespace of this module