diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix
index 271119031395..1eb2d953ebbe 100644
--- a/lib/tests/misc.nix
+++ b/lib/tests/misc.nix
@@ -913,4 +913,156 @@ runTests {
     };
   };
 
+  ## Levenshtein distance functions and co.
+  testCommonPrefixLengthEmpty = {
+    expr = strings.commonPrefixLength "" "hello";
+    expected = 0;
+  };
+
+  testCommonPrefixLengthSame = {
+    expr = strings.commonPrefixLength "hello" "hello";
+    expected = 5;
+  };
+
+  testCommonPrefixLengthDiffering = {
+    expr = strings.commonPrefixLength "hello" "hey";
+    expected = 2;
+  };
+
+  testCommonSuffixLengthEmpty = {
+    expr = strings.commonSuffixLength "" "hello";
+    expected = 0;
+  };
+
+  testCommonSuffixLengthSame = {
+    expr = strings.commonSuffixLength "hello" "hello";
+    expected = 5;
+  };
+
+  testCommonSuffixLengthDiffering = {
+    expr = strings.commonSuffixLength "test" "rest";
+    expected = 3;
+  };
+
+  testLevenshteinEmpty = {
+    expr = strings.levenshtein "" "";
+    expected = 0;
+  };
+
+  testLevenshteinOnlyAdd = {
+    expr = strings.levenshtein "" "hello there";
+    expected = 11;
+  };
+
+  testLevenshteinOnlyRemove = {
+    expr = strings.levenshtein "hello there" "";
+    expected = 11;
+  };
+
+  testLevenshteinOnlyTransform = {
+    expr = strings.levenshtein "abcdef" "ghijkl";
+    expected = 6;
+  };
+
+  testLevenshteinMixed = {
+    expr = strings.levenshtein "kitchen" "sitting";
+    expected = 5;
+  };
+
+  testLevenshteinAtMostZeroFalse = {
+    expr = strings.levenshteinAtMost 0 "foo" "boo";
+    expected = false;
+  };
+
+  testLevenshteinAtMostZeroTrue = {
+    expr = strings.levenshteinAtMost 0 "foo" "foo";
+    expected = true;
+  };
+
+  testLevenshteinAtMostOneFalse = {
+    expr = strings.levenshteinAtMost 1 "car" "ct";
+    expected = false;
+  };
+
+  testLevenshteinAtMostOneTrue = {
+    expr = strings.levenshteinAtMost 1 "car" "cr";
+    expected = true;
+  };
+
+  # We test levenshteinAtMost 2 particularly well because it uses a complicated
+  # implementation
+  testLevenshteinAtMostTwoIsEmpty = {
+    expr = strings.levenshteinAtMost 2 "" "";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoIsZero = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "abcdef";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoIsOne = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "abddef";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff0False = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "aczyef";
+    expected = false;
+  };
+
+  testLevenshteinAtMostTwoDiff0Outer = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "zbcdez";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff0DelLeft = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "bcdefz";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff0DelRight = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "zabcde";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff1False = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "bddez";
+    expected = false;
+  };
+
+  testLevenshteinAtMostTwoDiff1DelLeft = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "bcdez";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff1DelRight = {
+    expr = strings.levenshteinAtMost 2 "abcdef" "zbcde";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff2False = {
+    expr = strings.levenshteinAtMost 2 "hello" "hxo";
+    expected = false;
+  };
+
+  testLevenshteinAtMostTwoDiff2True = {
+    expr = strings.levenshteinAtMost 2 "hello" "heo";
+    expected = true;
+  };
+
+  testLevenshteinAtMostTwoDiff3 = {
+    expr = strings.levenshteinAtMost 2 "hello" "ho";
+    expected = false;
+  };
+
+  testLevenshteinAtMostThreeFalse = {
+    expr = strings.levenshteinAtMost 3 "hello" "Holla!";
+    expected = false;
+  };
+
+  testLevenshteinAtMostThreeTrue = {
+    expr = strings.levenshteinAtMost 3 "hello" "Holla";
+    expected = true;
+  };
 }