add tests

Author: tamaroning

tests/ui/map_then_identity_transformer.rs

@@ -1,9 +1,36 @@
 #![warn(clippy::map_then_identity_transformer)]
-#![allow(clippy::map_identity)]
+#![allow(clippy::map_identity, clippy::redundant_closure, clippy::unnecessary_filter_map)]
 
 fn main() {
     let a = [1, 2, 3];
+    let b = ["ABC", "DEF", "GHI"];
 
-    let _ = a.into_iter().map(|x| x > 0).all(|x| x);
-    let _ = a.into_iter().map(|x| x + x > 0).all(|x| x);
+    // should lint
+    let _ = a.into_iter().map(|x| bar(foo(x)) && foo(x)).all(|y| !y);
+    let _ = a.into_iter().map(|x| x > 1).all(|y| y);
+    let _ = a.into_iter().map(|x| foo(x)).any(|y| y);
+    let _ = a.into_iter().map(|x| x + 10).find(|&y| y == 10);
+    let _ = a.into_iter().map(|x| x + 10).find_map(|y| Some(y));
+    let _ = b.into_iter().map(|x| x).flat_map(|y| y.chars());
+    let _ = a.into_iter().map(|x| foo(x)).filter_map(|y| Some(!y));
+    let _ = a.into_iter().map(|x| x + 30).fold(1, |pd, x| pd * x + 1);
+    let _ = a.into_iter().map(|x| foo(x)).map(|y| bar(y));
+
+    // should not lint
+    let _ = a.into_iter().map(|x| x > 1).all(|y| foo(0));
+    let _ = a.into_iter().map(|x| foo(x)).any(|y| true);
+    let _ = a.into_iter().map(|x| 0).find(|&y| y == 10);
+    let _ = a.into_iter().map(|x| x * x).find_map(|y| Some(y));
+    let _ = b.into_iter().map(|x| "ABC").flat_map(|y| y.chars());
+    let _ = a.into_iter().map(|x| foo(x)).filter_map(|y| Some(true));
+    let _ = a.into_iter().map(|x| x + 30).fold(1, |pd, x| pd * x * x);
+    let _ = a.into_iter().map(|x| foo(x)).map(|y| bar(y) && y);
+}
+
+fn foo(a: i32) -> bool {
+    unimplemented!();
+}
+
+fn bar(a: bool) -> bool {
+    unimplemented!();
 }

tests/ui/map_then_identity_transformer.stderr

@@ -1,17 +1,97 @@
 error: this `map` can be collapsed into the `all`
-  --> $DIR/map_then_identity_transformer.rs:7:27
+  --> $DIR/map_then_identity_transformer.rs:10:27
    |
-LL |     let _ = a.into_iter().map(|x| x > 0).all(|x| x);
+LL |     let _ = a.into_iter().map(|x| x > 1).all(|y| y);
    |                           ^^^
    |
    = note: `-D clippy::map-then-identity-transformer` implied by `-D warnings`
 help: these `map` and `all` can be merged into a single `all`
-  --> $DIR/map_then_identity_transformer.rs:7:35
+  --> $DIR/map_then_identity_transformer.rs:10:35
    |
-LL |     let _ = a.into_iter().map(|x| x > 0).all(|x| x);
+LL |     let _ = a.into_iter().map(|x| x > 1).all(|y| y);
    |                                   ^^^^^          ^ replace this variable
    |                                   |
    |                                   with this expression
 
-error: aborting due to previous error
+error: this `map` can be collapsed into the `any`
+  --> $DIR/map_then_identity_transformer.rs:11:27
+   |
+LL |     let _ = a.into_iter().map(|x| foo(x)).any(|y| y);
+   |                           ^^^
+   |
+help: these `map` and `any` can be merged into a single `any`
+  --> $DIR/map_then_identity_transformer.rs:11:35
+   |
+LL |     let _ = a.into_iter().map(|x| foo(x)).any(|y| y);
+   |                                   ^^^^^^          ^ replace this variable
+   |                                   |
+   |                                   with this expression
+
+error: this `map` can be collapsed into the `find_map`
+  --> $DIR/map_then_identity_transformer.rs:13:27
+   |
+LL |     let _ = a.into_iter().map(|x| x + 10).find_map(|y| Some(y));
+   |                           ^^^
+   |
+help: these `map` and `find_map` can be merged into a single `find_map`
+  --> $DIR/map_then_identity_transformer.rs:13:35
+   |
+LL |     let _ = a.into_iter().map(|x| x + 10).find_map(|y| Some(y));
+   |                                   ^^^^^^                    ^ replace this variable
+   |                                   |
+   |                                   with this expression
+
+error: this `map` can be collapsed into the `flat_map`
+  --> $DIR/map_then_identity_transformer.rs:14:27
+   |
+LL |     let _ = b.into_iter().map(|x| x).flat_map(|y| y.chars());
+   |                           ^^^
+   |
+help: these `map` and `flat_map` can be merged into a single `flat_map`
+  --> $DIR/map_then_identity_transformer.rs:14:35
+   |
+LL |     let _ = b.into_iter().map(|x| x).flat_map(|y| y.chars());
+   |                                   ^               ^ replace this variable
+   |                                   |
+   |                                   with this expression
+
+error: this `map` can be collapsed into the `filter_map`
+  --> $DIR/map_then_identity_transformer.rs:15:27
+   |
+LL |     let _ = a.into_iter().map(|x| foo(x)).filter_map(|y| Some(!y));
+   |                           ^^^
+   |
+help: these `map` and `filter_map` can be merged into a single `filter_map`
+  --> $DIR/map_then_identity_transformer.rs:15:35
+   |
+LL |     let _ = a.into_iter().map(|x| foo(x)).filter_map(|y| Some(!y));
+   |                                   ^^^^^^ with this expression  ^ replace this variable
+
+error: this `map` can be collapsed into the `fold`
+  --> $DIR/map_then_identity_transformer.rs:16:27
+   |
+LL |     let _ = a.into_iter().map(|x| x + 30).fold(1, |pd, x| pd * x + 1);
+   |                           ^^^
+   |
+help: these `map` and `fold` can be merged into a single `fold`
+  --> $DIR/map_then_identity_transformer.rs:16:35
+   |
+LL |     let _ = a.into_iter().map(|x| x + 30).fold(1, |pd, x| pd * x + 1);
+   |                                   ^^^^^^ with this expression  ^ replace this variable
+
+error: this `map` can be collapsed into the `map`
+  --> $DIR/map_then_identity_transformer.rs:17:27
+   |
+LL |     let _ = a.into_iter().map(|x| foo(x)).map(|y| bar(y));
+   |                           ^^^
+   |
+help: these `map` and `map` can be merged into a single `map`
+  --> $DIR/map_then_identity_transformer.rs:17:35
+   |
+LL |     let _ = a.into_iter().map(|x| foo(x)).map(|y| bar(y));
+   |                                   ^^^^^^              ^ replace this variable
+   |                                   |
+   |                                   with this expression
+
+error: aborting due to 7 previous errors