2 files changed, 103 insertions, 0 deletions
diff --git a/lib/path/tests/default.nix b/lib/path/tests/default.nix
new file mode 100644
index 000000000000..784a3af68b6e
--- /dev/null
+++ b/lib/path/tests/default.nix
@@ -0,0 +1,27 @@
+{
+  nixpkgs ? ../../..,
+  system ? builtins.currentSystem,
+  pkgs ? import nixpkgs {
+    config = {};
+    overlays = [];
+    inherit system;
+  },
+  libpath ? ../..,
+}:
+pkgs.runCommand "lib-path-tests" {
+  nativeBuildInputs = with pkgs; [
+    nix
+  ];
+} ''
+  # Needed to make Nix evaluation work
+  export NIX_STATE_DIR=$(mktemp -d)
+
+  cp -r ${libpath} lib
+  export TEST_LIB=$PWD/lib
+
+  echo "Running unit tests lib/path/tests/unit.nix"
+  nix-instantiate --eval lib/path/tests/unit.nix \
+    --argstr libpath "$TEST_LIB"
+
+  touch $out
+''
diff --git a/lib/path/tests/unit.nix b/lib/path/tests/unit.nix
new file mode 100644
index 000000000000..15f5940a51e0
--- /dev/null
+++ b/lib/path/tests/unit.nix
@@ -0,0 +1,76 @@
+# Unit tests for lib.path functions. Use `nix-build` in this directory to
+# run these
+{ libpath }:
+let
+  lib = import libpath;
+  inherit (lib.path) subpath;
+
+  cases = lib.runTests {
+    testSubpathIsValidExample1 = {
+      expr = subpath.isValid null;
+      expected = false;
+    };
+    testSubpathIsValidExample2 = {
+      expr = subpath.isValid "";
+      expected = false;
+    };
+    testSubpathIsValidExample3 = {
+      expr = subpath.isValid "/foo";
+      expected = false;
+    };
+    testSubpathIsValidExample4 = {
+      expr = subpath.isValid "../foo";
+      expected = false;
+    };
+    testSubpathIsValidExample5 = {
+      expr = subpath.isValid "foo/bar";
+      expected = true;
+    };
+    testSubpathIsValidExample6 = {
+      expr = subpath.isValid "./foo//bar/";
+      expected = true;
+    };
+    testSubpathIsValidTwoDotsEnd = {
+      expr = subpath.isValid "foo/..";
+      expected = false;
+    };
+    testSubpathIsValidTwoDotsMiddle = {
+      expr = subpath.isValid "foo/../bar";
+      expected = false;
+    };
+    testSubpathIsValidTwoDotsPrefix = {
+      expr = subpath.isValid "..foo";
+      expected = true;
+    };
+    testSubpathIsValidTwoDotsSuffix = {
+      expr = subpath.isValid "foo..";
+      expected = true;
+    };
+    testSubpathIsValidTwoDotsPrefixComponent = {
+      expr = subpath.isValid "foo/..bar/baz";
+      expected = true;
+    };
+    testSubpathIsValidTwoDotsSuffixComponent = {
+      expr = subpath.isValid "foo/bar../baz";
+      expected = true;
+    };
+    testSubpathIsValidThreeDots = {
+      expr = subpath.isValid "...";
+      expected = true;
+    };
+    testSubpathIsValidFourDots = {
+      expr = subpath.isValid "....";
+      expected = true;
+    };
+    testSubpathIsValidThreeDotsComponent = {
+      expr = subpath.isValid "foo/.../bar";
+      expected = true;
+    };
+    testSubpathIsValidFourDotsComponent = {
+      expr = subpath.isValid "foo/..../bar";
+      expected = true;
+    };
+  };
+in
+  if cases == [] then "Unit tests successful"
+  else throw "Path unit tests failed: ${lib.generators.toPretty {} cases}"