Commit 5c4f6161 authored by Silvan Mosberger's avatar Silvan Mosberger
Browse files

lib.path: Minor improvements 

- Use isValid when possible instead of subpathInvalidReason: https://github.com/NixOS/nixpkgs/pull/209099#discussion_r1068714681
- Add documentation to function arguments
- Use newlines for error messages: https://github.com/NixOS/nixpkgs/pull/208887#discussion_r1069737602
- Add short comments for the unit test groups: https://github.com/NixOS/nixpkgs/pull/208887#discussion_r1072913051
- Slight formatting improvement for laws: https://github.com/NixOS/nixpkgs/pull/209099#discussion_r1068707955
parent 0667ef5d

lib/path/default.nix

+16 −7
Original line number Diff line number Diff line
@@ -25,6 +25,10 @@ let 
    assertMsg

    ;



  inherit (lib.path.subpath)

    isValid

    ;



  # Return the reason why a subpath is invalid, or `null` if it's valid

  subpathInvalidReason = value:

    if ! isString value then
@@ -133,7 +137,9 @@ in /* No rec! Add dependencies on this file at the top. */ { 
    subpath.isValid "./foo//bar/"

    => true

  */

  subpath.isValid = value:

  subpath.isValid =

    # The value to check

    value:

    subpathInvalidReason value == null;
@@ -150,11 +156,11 @@ in /* No rec! Add dependencies on this file at the top. */ { 


  Laws:



  - (Idempotency) Normalising multiple times gives the same result:

  - Idempotency - normalising multiple times gives the same result:



        subpath.normalise (subpath.normalise p) == subpath.normalise p



  - (Uniqueness) There's only a single normalisation for the paths that lead to the same file system node:

  - Uniqueness - there's only a single normalisation for the paths that lead to the same file system node:



        subpath.normalise p != subpath.normalise q -> $(realpath ${p}) != $(realpath ${q})
@@ -210,9 +216,12 @@ in /* No rec! Add dependencies on this file at the top. */ { 
    subpath.normalise "/foo"

    => <error>

  */

  subpath.normalise = path:

    assert assertMsg (subpathInvalidReason path == null)

      "lib.path.subpath.normalise: Argument is not a valid subpath string: ${subpathInvalidReason path}";

    joinRelPath (splitRelPath path);

  subpath.normalise =

    # The subpath string to normalise

    subpath:

    assert assertMsg (isValid subpath) ''

      lib.path.subpath.normalise: Argument is not a valid subpath string:

          ${subpathInvalidReason subpath}'';

    joinRelPath (splitRelPath subpath);



}

lib/path/tests/unit.nix

+4 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ let 
  inherit (lib.path) subpath;



  cases = lib.runTests {

    # Test examples from the lib.path.subpath.isValid documentation

    testSubpathIsValidExample1 = {

      expr = subpath.isValid null;

      expected = false;
@@ -30,6 +31,7 @@ let 
      expr = subpath.isValid "./foo//bar/";

      expected = true;

    };

    # Some extra tests

    testSubpathIsValidTwoDotsEnd = {

      expr = subpath.isValid "foo/..";

      expected = false;
@@ -71,6 +73,7 @@ let 
      expected = true;

    };



    # Test examples from the lib.path.subpath.normalise documentation

    testSubpathNormaliseExample1 = {

      expr = subpath.normalise "foo//bar";

      expected = "./foo/bar";
@@ -107,6 +110,7 @@ let 
      expr = (builtins.tryEval (subpath.normalise "/foo")).success;

      expected = false;

    };

    # Some extra tests

    testSubpathNormaliseIsValidDots = {

      expr = subpath.normalise "./foo/.bar/.../baz...qux";

      expected = "./foo/.bar/.../baz...qux";