1 files changed, 94 insertions, 0 deletions
diff --git a/nix/tag/tests.nix b/nix/tag/tests.nix
new file mode 100644
index 0000000000..bcc42c758a
--- /dev/null
+++ b/nix/tag/tests.nix
@@ -0,0 +1,94 @@
+{ depot, lib, verifyTag, discr, discrDef, match, matchLam }:
+
+let
+  inherit (depot.nix.runTestsuite)
+    runTestsuite
+    assertEq
+    it
+    ;
+
+  isTag-test = it "checks whether something is a tag" [
+    (assertEq "is Tag"
+      (verifyTag { foo = "bar"; })
+      {
+        isTag = true;
+        name = "foo";
+        val = "bar";
+        errmsg = null;
+      })
+    (assertEq "is not Tag"
+      (removeAttrs (verifyTag { foo = "bar"; baz = 42; }) [ "errmsg" ])
+      {
+        isTag = false;
+        name = null;
+        val = null;
+      })
+  ];
+
+  discr-test = it "can discr things" [
+    (assertEq "id"
+      (discr [
+        { a = lib.const true; }
+      ] "x")
+      { a = "x"; })
+    (assertEq "bools here, ints there"
+      (discr [
+        { bool = lib.isBool; }
+        { int = lib.isInt; }
+      ] 25)
+      { int = 25; })
+    (assertEq "bools here, ints there 2"
+      (discr [
+        { bool = lib.isBool; }
+        { int = lib.isInt; }
+      ]
+        true)
+      { bool = true; })
+    (assertEq "fallback to default"
+      (discrDef "def" [
+        { bool = lib.isBool; }
+        { int = lib.isInt; }
+      ] "foo")
+      { def = "foo"; })
+  ];
+
+  match-test = it "can match things" [
+    (assertEq "match example"
+      (
+        let
+          success = { res = 42; };
+          failure = { err = "no answer"; };
+          matcher = {
+            res = i: i + 1;
+            err = _: 0;
+          };
+        in
+        {
+          one = match success matcher;
+          two = match failure matcher;
+        }
+      )
+      {
+        one = 43;
+        two = 0;
+      })
+    (assertEq "matchLam & pipe"
+      (lib.pipe { foo = 42; } [
+        (matchLam {
+          foo = i: if i < 23 then { small = i; } else { big = i; };
+          bar = _: { small = 5; };
+        })
+        (matchLam {
+          small = i: "yay it was small";
+          big = i: "whoo it was big!";
+        })
+      ])
+      "whoo it was big!")
+  ];
+
+in
+runTestsuite "tag" [
+  isTag-test
+  discr-test
+  match-test
+]