lib/tests: add tests for hasInfix

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>

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 = {