diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix
index c5d1d431677a..a0be581d37fb 100644
--- a/lib/tests/misc.nix
+++ b/lib/tests/misc.nix
@@ -271,6 +271,36 @@ runTests {
     '';
   };
 
+  testHasInfixFalse = {
+    expr = hasInfix "c" "abde";
+    expected = false;
+  };
+
+  testHasInfixTrue = {
+    expr = hasInfix "c" "abcde";
+    expected = true;
+  };
+
+  testHasInfixDerivation = {
+    expr = hasInfix "hello" (import ../.. { system = "x86_64-linux"; }).hello;
+    expected = true;
+  };
+
+  testHasInfixPath = {
+    expr = hasInfix "tests" ./.;
+    expected = true;
+  };
+
+  testHasInfixPathStoreDir = {
+    expr = hasInfix builtins.storeDir ./.;
+    expected = true;
+  };
+
+  testHasInfixToString = {
+    expr = hasInfix "a" { __toString = _: "a"; };
+    expected = true;
+  };
+
 # LISTS
 
   testFilter = {