add many tests

Signed-off-by: TennyZhuang <zty0826@gmail.com>

tests/ui/partial_pub_fields.rs

@@ -2,8 +2,6 @@
 #![warn(clippy::partial_pub_fields)]
 
 fn main() {
-    // test code goes here
-
     use std::collections::HashMap;
 
     #[derive(Default)]
@@ -17,4 +15,26 @@ fn main() {
         pub g: u8,
         b: u8,
     }
+
+    pub struct Point(i32, pub i32);
+
+    pub struct Visibility {
+        r#pub: bool,
+        pub pos: u32,
+    }
+
+    // Don't lint on empty structs;
+    pub struct Empty1;
+    pub struct Empty2();
+    pub struct Empty3 {};
+
+    // Don't lint on structs with one field.
+    pub struct Single1(i32);
+    pub struct Single2(pub i32);
+    pub struct Single3 {
+        v1: i32,
+    }
+    pub struct Single3 {
+        pub v1: i32,
+    }
 }

tests/ui/partial_pub_fields.stderr

@@ -1,5 +1,16 @@
+error[E0428]: the name `Single3` is defined multiple times
+  --> $DIR/partial_pub_fields.rs:37:5
+   |
+LL |     pub struct Single3 {
+   |     ------------------ previous definition of the type `Single3` here
+...
+LL |     pub struct Single3 {
+   |     ^^^^^^^^^^^^^^^^^^ `Single3` redefined here
+   |
+   = note: `Single3` must be defined only once in the type namespace of this block
+
 error: mixed usage of pub and non-pub fields
-  --> $DIR/partial_pub_fields.rs:12:9
+  --> $DIR/partial_pub_fields.rs:10:9
    |
 LL |         pub paths: HashMap<u32, String>,
    |         ^^^
@@ -8,12 +19,29 @@ LL |         pub paths: HashMap<u32, String>,
    = note: `-D clippy::partial-pub-fields` implied by `-D warnings`
 
 error: mixed usage of pub and non-pub fields
-  --> $DIR/partial_pub_fields.rs:18:9
+  --> $DIR/partial_pub_fields.rs:16:9
    |
 LL |         b: u8,
    |         ^
    |
    = help: consider using public field here
 
-error: aborting due to 2 previous errors
+error: mixed usage of pub and non-pub fields
+  --> $DIR/partial_pub_fields.rs:19:27
+   |
+LL |     pub struct Point(i32, pub i32);
+   |                           ^^^
+   |
+   = help: consider using private field here
+
+error: mixed usage of pub and non-pub fields
+  --> $DIR/partial_pub_fields.rs:23:9
+   |
+LL |         pub pos: u32,
+   |         ^^^
+   |
+   = help: consider using private field here
+
+error: aborting due to 5 previous errors
 
+For more information about this error, try `rustc --explain E0428`.