diff --git a/tests/ui/zero_sized_btreemap_values.rs b/tests/ui/zero_sized_btreemap_values.rs
new file mode 100644
index 000000000000..5cd254787d83
--- /dev/null
+++ b/tests/ui/zero_sized_btreemap_values.rs
@@ -0,0 +1,68 @@
+#![warn(clippy::zero_sized_map_values)]
+use std::collections::BTreeMap;
+
+const CONST_OK: Option<BTreeMap<String, usize>> = None;
+const CONST_NOT_OK: Option<BTreeMap<String, ()>> = None;
+
+static STATIC_OK: Option<BTreeMap<String, usize>> = None;
+static STATIC_NOT_OK: Option<BTreeMap<String, ()>> = None;
+
+type OkMap = BTreeMap<String, usize>;
+type NotOkMap = BTreeMap<String, ()>;
+
+enum TestEnum {
+    Ok(BTreeMap<String, usize>),
+    NotOk(BTreeMap<String, ()>),
+}
+
+struct Test {
+    ok: BTreeMap<String, usize>,
+    not_ok: BTreeMap<String, ()>,
+
+    also_not_ok: Vec<BTreeMap<usize, ()>>,
+}
+
+trait TestTrait {
+    type Output;
+
+    fn produce_output() -> Self::Output;
+
+    fn weird_map(&self, map: BTreeMap<usize, ()>);
+}
+
+impl Test {
+    fn ok(&self) -> BTreeMap<String, usize> {
+        todo!()
+    }
+
+    fn not_ok(&self) -> BTreeMap<String, ()> {
+        todo!()
+    }
+}
+
+impl TestTrait for Test {
+    type Output = BTreeMap<String, ()>;
+
+    fn produce_output() -> Self::Output {
+        todo!();
+    }
+
+    fn weird_map(&self, map: BTreeMap<usize, ()>) {
+        todo!();
+    }
+}
+
+fn test(map: BTreeMap<String, ()>, key: &str) -> BTreeMap<String, ()> {
+    todo!();
+}
+
+fn test2(map: BTreeMap<String, usize>, key: &str) -> BTreeMap<String, usize> {
+    todo!();
+}
+
+fn main() {
+    let _: BTreeMap<String, ()> = BTreeMap::new();
+    let _: BTreeMap<String, usize> = BTreeMap::new();
+
+    let _: BTreeMap<_, _> = std::iter::empty::<(String, ())>().collect();
+}
diff --git a/tests/ui/zero_sized_btreemap_values.stderr b/tests/ui/zero_sized_btreemap_values.stderr
new file mode 100644
index 000000000000..334d921a9af3
--- /dev/null
+++ b/tests/ui/zero_sized_btreemap_values.stderr
@@ -0,0 +1,107 @@
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:5:28
+   |
+LL | const CONST_NOT_OK: Option<BTreeMap<String, ()>> = None;
+   |                            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::zero-sized-map-values` implied by `-D warnings`
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:8:30
+   |
+LL | static STATIC_NOT_OK: Option<BTreeMap<String, ()>> = None;
+   |                              ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:11:17
+   |
+LL | type NotOkMap = BTreeMap<String, ()>;
+   |                 ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:15:11
+   |
+LL |     NotOk(BTreeMap<String, ()>),
+   |           ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:20:13
+   |
+LL |     not_ok: BTreeMap<String, ()>,
+   |             ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:22:22
+   |
+LL |     also_not_ok: Vec<BTreeMap<usize, ()>>,
+   |                      ^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:30:30
+   |
+LL |     fn weird_map(&self, map: BTreeMap<usize, ()>);
+   |                              ^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:38:25
+   |
+LL |     fn not_ok(&self) -> BTreeMap<String, ()> {
+   |                         ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:55:14
+   |
+LL | fn test(map: BTreeMap<String, ()>, key: &str) -> BTreeMap<String, ()> {
+   |              ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:55:50
+   |
+LL | fn test(map: BTreeMap<String, ()>, key: &str) -> BTreeMap<String, ()> {
+   |                                                  ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:64:35
+   |
+LL |     let _: BTreeMap<String, ()> = BTreeMap::new();
+   |                                   ^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:64:12
+   |
+LL |     let _: BTreeMap<String, ()> = BTreeMap::new();
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: map with zero-sized value type
+  --> $DIR/zero_sized_btreemap_values.rs:67:12
+   |
+LL |     let _: BTreeMap<_, _> = std::iter::empty::<(String, ())>().collect();
+   |            ^^^^^^^^^^^^^^
+   |
+   = help: consider using a set instead
+
+error: aborting due to 13 previous errors
+
diff --git a/tests/ui/zero_sized_map_values.rs b/tests/ui/zero_sized_hashmap_values.rs
similarity index 90%
rename from tests/ui/zero_sized_map_values.rs
rename to tests/ui/zero_sized_hashmap_values.rs
index 09519b0011c5..a1608d863fb5 100644
--- a/tests/ui/zero_sized_map_values.rs
+++ b/tests/ui/zero_sized_hashmap_values.rs
@@ -1,5 +1,5 @@
 #![warn(clippy::zero_sized_map_values)]
-use std::collections::{BTreeMap, HashMap};
+use std::collections::HashMap;
 
 const CONST_OK: Option<HashMap<String, usize>> = None;
 const CONST_NOT_OK: Option<HashMap<String, ()>> = None;
@@ -61,10 +61,8 @@ fn test2(map: HashMap<String, usize>, key: &str) -> HashMap<String, usize> {
 }
 
 fn main() {
-    // test code goes here
     let _: HashMap<String, ()> = HashMap::new();
     let _: HashMap<String, usize> = HashMap::new();
 
     let _: HashMap<_, _> = std::iter::empty::<(String, ())>().collect();
-    let _: BTreeMap<_, _> = std::iter::empty::<(String, ())>().collect();
 }
diff --git a/tests/ui/zero_sized_map_values.stderr b/tests/ui/zero_sized_hashmap_values.stderr
similarity index 75%
rename from tests/ui/zero_sized_map_values.stderr
rename to tests/ui/zero_sized_hashmap_values.stderr
index 984ac401aa24..43987b3d01d1 100644
--- a/tests/ui/zero_sized_map_values.stderr
+++ b/tests/ui/zero_sized_hashmap_values.stderr
@@ -1,5 +1,5 @@
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:5:28
+  --> $DIR/zero_sized_hashmap_values.rs:5:28
    |
 LL | const CONST_NOT_OK: Option<HashMap<String, ()>> = None;
    |                            ^^^^^^^^^^^^^^^^^^^
@@ -8,7 +8,7 @@ LL | const CONST_NOT_OK: Option<HashMap<String, ()>> = None;
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:8:30
+  --> $DIR/zero_sized_hashmap_values.rs:8:30
    |
 LL | static STATIC_NOT_OK: Option<HashMap<String, ()>> = None;
    |                              ^^^^^^^^^^^^^^^^^^^
@@ -16,7 +16,7 @@ LL | static STATIC_NOT_OK: Option<HashMap<String, ()>> = None;
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:11:17
+  --> $DIR/zero_sized_hashmap_values.rs:11:17
    |
 LL | type NotOkMap = HashMap<String, ()>;
    |                 ^^^^^^^^^^^^^^^^^^^
@@ -24,7 +24,7 @@ LL | type NotOkMap = HashMap<String, ()>;
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:15:11
+  --> $DIR/zero_sized_hashmap_values.rs:15:11
    |
 LL |     NotOk(HashMap<String, ()>),
    |           ^^^^^^^^^^^^^^^^^^^
@@ -32,7 +32,7 @@ LL |     NotOk(HashMap<String, ()>),
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:20:13
+  --> $DIR/zero_sized_hashmap_values.rs:20:13
    |
 LL |     not_ok: HashMap<String, ()>,
    |             ^^^^^^^^^^^^^^^^^^^
@@ -40,7 +40,7 @@ LL |     not_ok: HashMap<String, ()>,
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:22:22
+  --> $DIR/zero_sized_hashmap_values.rs:22:22
    |
 LL |     also_not_ok: Vec<HashMap<usize, ()>>,
    |                      ^^^^^^^^^^^^^^^^^^
@@ -48,7 +48,7 @@ LL |     also_not_ok: Vec<HashMap<usize, ()>>,
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:30:30
+  --> $DIR/zero_sized_hashmap_values.rs:30:30
    |
 LL |     fn weird_map(&self, map: HashMap<usize, ()>);
    |                              ^^^^^^^^^^^^^^^^^^
@@ -56,7 +56,7 @@ LL |     fn weird_map(&self, map: HashMap<usize, ()>);
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:38:25
+  --> $DIR/zero_sized_hashmap_values.rs:38:25
    |
 LL |     fn not_ok(&self) -> HashMap<String, ()> {
    |                         ^^^^^^^^^^^^^^^^^^^
@@ -64,7 +64,7 @@ LL |     fn not_ok(&self) -> HashMap<String, ()> {
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:55:14
+  --> $DIR/zero_sized_hashmap_values.rs:55:14
    |
 LL | fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
    |              ^^^^^^^^^^^^^^^^^^^
@@ -72,7 +72,7 @@ LL | fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:55:49
+  --> $DIR/zero_sized_hashmap_values.rs:55:49
    |
 LL | fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
    |                                                 ^^^^^^^^^^^^^^^^^^^
@@ -80,7 +80,7 @@ LL | fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:65:34
+  --> $DIR/zero_sized_hashmap_values.rs:64:34
    |
 LL |     let _: HashMap<String, ()> = HashMap::new();
    |                                  ^^^^^^^^^^^^
@@ -88,7 +88,7 @@ LL |     let _: HashMap<String, ()> = HashMap::new();
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:65:12
+  --> $DIR/zero_sized_hashmap_values.rs:64:12
    |
 LL |     let _: HashMap<String, ()> = HashMap::new();
    |            ^^^^^^^^^^^^^^^^^^^
@@ -96,20 +96,12 @@ LL |     let _: HashMap<String, ()> = HashMap::new();
    = help: consider using a set instead
 
 error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:68:12
+  --> $DIR/zero_sized_hashmap_values.rs:67:12
    |
 LL |     let _: HashMap<_, _> = std::iter::empty::<(String, ())>().collect();
    |            ^^^^^^^^^^^^^
    |
    = help: consider using a set instead
 
-error: map with zero-sized value type
-  --> $DIR/zero_sized_map_values.rs:69:12
-   |
-LL |     let _: BTreeMap<_, _> = std::iter::empty::<(String, ())>().collect();
-   |            ^^^^^^^^^^^^^^
-   |
-   = help: consider using a set instead
-
-error: aborting due to 14 previous errors
+error: aborting due to 13 previous errors