From 5e938ebb20446dc2b38349388d16b2590f778223 Mon Sep 17 00:00:00 2001
From: DavHau <hsngrmpf+github@gmail.com>
Date: Tue, 10 Oct 2023 18:54:51 +0200
Subject: [PATCH] findCycles: add some unit tests

---
 .../dream2nix-repo-single-package/flake.nix   |  28 ++
 tests/nix-unit/test_findCycles/default.nix    | 272 ++++++++++++++++++
 2 files changed, 300 insertions(+)
 create mode 100644 examples/dream2nix-repo-single-package/flake.nix
 create mode 100644 tests/nix-unit/test_findCycles/default.nix

diff --git a/examples/dream2nix-repo-single-package/flake.nix b/examples/dream2nix-repo-single-package/flake.nix
new file mode 100644
index 0000000000..1e46fd973b
--- /dev/null
+++ b/examples/dream2nix-repo-single-package/flake.nix
@@ -0,0 +1,28 @@
+{
+  description = "My flake with dream2nix packages";
+
+  inputs = {
+    dream2nix.url = "github:nix-community/dream2nix";
+    nixpkgs.follows = "dream2nix/nixpkgs";
+  };
+
+  outputs = inputs @ {
+    self,
+    dream2nix,
+    nixpkgs,
+    ...
+  }: let
+    system = "x86_64-linux";
+  in {
+    # all packages defined inside ./packages/
+    packages.${system}.default = nixpkgs.lib.evalModules {
+      modules = [];
+
+      projectRoot = ./.;
+      # can be changed to ".git" or "flake.nix" to get rid of .project-root
+      projectRootFile = "flake.nix";
+      packagesDir = ./packages;
+      packageSets.nixpkgs = nixpkgs.legacyPackages.${system};
+    };
+  };
+}
diff --git a/tests/nix-unit/test_findCycles/default.nix b/tests/nix-unit/test_findCycles/default.nix
new file mode 100644
index 0000000000..f0f98399a6
--- /dev/null
+++ b/tests/nix-unit/test_findCycles/default.nix
@@ -0,0 +1,272 @@
+{
+  pkgs ? import <nixpkgs> {},
+  lib ? import <nixpkgs/lib>,
+  ...
+}: let
+  findCycles = import ../../../lib/internal/findCycles.nix {inherit lib;};
+in {
+  test_simple = {
+    expr = findCycles {
+      dependencyGraph = {
+        a.v1 = [
+          {
+            name = "b";
+            version = "v1";
+          }
+        ];
+        b.v1 = [
+          {
+            name = "a";
+            version = "v1";
+          }
+        ];
+      };
+      roots = {
+        a = "v1";
+      };
+    };
+    expected = {
+      b.v1 = [
+        {
+          name = "a";
+          version = "v1";
+        }
+      ];
+    };
+  };
+
+  test_cycle_length_3 = {
+    expr = findCycles {
+      dependencyGraph = {
+        a.v1 = [
+          {
+            name = "b";
+            version = "v1";
+          }
+        ];
+        b.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+        c.v1 = [
+          {
+            name = "a";
+            version = "v1";
+          }
+        ];
+      };
+      roots = {
+        a = "v1";
+      };
+    };
+    expected = {
+      c.v1 = [
+        {
+          name = "a";
+          version = "v1";
+        }
+      ];
+    };
+  };
+
+  test_two_roots_both_chosen = {
+    expr = findCycles {
+      dependencyGraph = {
+        a.v1 = [
+          {
+            name = "b";
+            version = "v1";
+          }
+        ];
+        b.v1 = [
+          {
+            name = "a";
+            version = "v1";
+          }
+        ];
+        c.v1 = [
+          {
+            name = "d";
+            version = "v1";
+          }
+        ];
+        d.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+      };
+      roots = {
+        a = "v1";
+        c = "v1";
+      };
+    };
+    expected = {
+      b.v1 = [
+        {
+          name = "a";
+          version = "v1";
+        }
+      ];
+      d.v1 = [
+        {
+          name = "c";
+          version = "v1";
+        }
+      ];
+    };
+  };
+
+  test_two_roots_one_chosen = {
+    expr = findCycles {
+      dependencyGraph = {
+        a.v1 = [
+          {
+            name = "b";
+            version = "v1";
+          }
+        ];
+        b.v1 = [
+          {
+            name = "a";
+            version = "v1";
+          }
+        ];
+        c.v1 = [
+          {
+            name = "d";
+            version = "v1";
+          }
+        ];
+        d.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+      };
+      roots = {
+        a = "v1";
+      };
+    };
+    expected = {
+      b.v1 = [
+        {
+          name = "a";
+          version = "v1";
+        }
+      ];
+    };
+  };
+
+  test_c_visited_twice_no_cycle = {
+    expr = findCycles {
+      dependencyGraph = {
+        a.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+        b.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+        c.v1 = [];
+      };
+      roots = {
+        a = "v1";
+        b = "v1";
+      };
+    };
+    expected = {};
+  };
+
+  test_two_cycles_one_root = {
+    expr = findCycles {
+      dependencyGraph = {
+        a.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+        b.v1 = [
+          {
+            name = "c";
+            version = "v1";
+          }
+        ];
+        c.v1 = [
+          {
+            name = "d";
+            version = "v1";
+          }
+        ];
+        d.v1 = [
+          {
+            name = "a";
+            version = "v1";
+          }
+          {
+            name = "b";
+            version = "v1";
+          }
+        ];
+      };
+      roots = {
+        a = "v1";
+      };
+    };
+    expected = {
+      d.v1 = [
+        {
+          name = "a";
+          version = "v1";
+        }
+      ];
+      b.v1 = [
+        {
+          name = "c";
+          version = "v1";
+        }
+      ];
+    };
+  };
+
+  # TODO: fix the implementation to remove furthest edges from the root only
+  # test_two_cycles_two_roots = {
+  #   expr = findCycles {
+  #     dependencyGraph = {
+  #       a.v1 = [
+  #         {name = "c"; version = "v1";}
+  #       ];
+  #       b.v1 = [
+  #         {name = "c"; version = "v1";}
+  #       ];
+  #       c.v1 = [
+  #         {name = "d"; version = "v1";}
+  #       ];
+  #       d.v1 = [
+  #         {name = "a"; version = "v1";}
+  #         {name = "b"; version = "v1";}
+  #       ];
+  #     };
+  #     roots = {
+  #       a = "v1";
+  #       b = "v1";
+  #     };
+  #   };
+  #   expected = {
+  #     d.v1 = [
+  #       {name = "a"; version = "v1";}
+  #       {name = "b"; version = "v1";}
+  #     ];
+  #   };
+  # };
+}