1 files changed, 76 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/collapsible_str_replace.rs b/src/tools/clippy/tests/ui/collapsible_str_replace.rs
new file mode 100644
index 000000000..e3e25c414
--- /dev/null
+++ b/src/tools/clippy/tests/ui/collapsible_str_replace.rs
@@ -0,0 +1,76 @@
+// run-rustfix
+
+#![warn(clippy::collapsible_str_replace)]
+
+fn get_filter() -> char {
+    'u'
+}
+
+fn main() {
+    let d = 'd';
+    let p = 'p';
+    let s = 's';
+    let u = 'u';
+    let l = "l";
+
+    let mut iter = ["l", "z"].iter();
+
+    // LINT CASES
+    let _ = "hesuo worpd".replace('s', "l").replace('u', "l");
+
+    let _ = "hesuo worpd".replace('s', l).replace('u', l);
+
+    let _ = "hesuo worpd".replace('s', "l").replace('u', "l").replace('p', "l");
+
+    let _ = "hesuo worpd"
+        .replace('s', "l")
+        .replace('u', "l")
+        .replace('p', "l")
+        .replace('d', "l");
+
+    let _ = "hesuo world".replace(s, "l").replace('u', "l");
+
+    let _ = "hesuo worpd".replace(s, "l").replace('u', "l").replace('p', "l");
+
+    let _ = "hesuo worpd".replace(s, "l").replace(u, "l").replace('p', "l");
+
+    let _ = "hesuo worpd".replace(s, "l").replace(u, "l").replace(p, "l");
+
+    let _ = "hesuo worlp".replace('s', "l").replace('u', "l").replace('p', "d");
+
+    let _ = "hesuo worpd".replace('s', "x").replace('u', "l").replace('p', "l");
+
+    // Note: Future iterations could lint `replace(|c| matches!(c, "su" | 'd' | 'p'), "l")`
+    let _ = "hesudo worpd".replace("su", "l").replace('d', "l").replace('p', "l");
+
+    let _ = "hesudo worpd".replace(d, "l").replace('p', "l").replace("su", "l");
+
+    let _ = "hesuo world".replace(get_filter(), "l").replace('s', "l");
+
+    // NO LINT CASES
+    let _ = "hesuo world".replace('s', "l").replace('u', "p");
+
+    let _ = "hesuo worpd".replace('s', "l").replace('p', l);
+
+    let _ = "hesudo worpd".replace('d', "l").replace("su", "l").replace('p', "l");
+
+    // Note: Future iterations of `collapsible_str_replace` might lint this and combine to `[s, u, p]`
+    let _ = "hesuo worpd".replace([s, u], "l").replace([u, p], "l");
+
+    let _ = "hesuo worpd".replace(['s', 'u'], "l").replace(['u', 'p'], "l");
+
+    let _ = "hesuo worpd".replace('s', "l").replace(['u', 'p'], "l");
+
+    let _ = "hesuo worpd".replace(['s', 'u', 'p'], "l").replace('r', "l");
+
+    let _ = "hesuo worpd".replace(['s', 'u', 'p'], l).replace('r', l);
+
+    let _ = "hesuo worpd".replace(['s', u, 'p'], "l").replace('r', "l");
+
+    let _ = "hesuo worpd".replace([s, u], "l").replace(p, "l");
+
+    // Regression test
+    let _ = "hesuo worpd"
+        .replace('u', iter.next().unwrap())
+        .replace('s', iter.next().unwrap());
+}