jaq: init passthru.tests

Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>

pkgs/by-name/ja/jaq/package.nix

@@ -4,6 +4,7 @@
   fetchFromGitHub,
   versionCheckHook,
   nix-update-script,
+  runCommand,
 }:
 
 rustPlatform.buildRustPackage (finalAttrs: {
@@ -25,7 +26,44 @@ rustPlatform.buildRustPackage (finalAttrs: {
   versionCheckProgramArg = "--version";
   doInstallCheck = true;
 
-  passthru.updateScript = nix-update-script { };
+  passthru = {
+    updateScript = nix-update-script { };
+    tests.simple =
+      runCommand "jaq-test"
+        {
+          nativeBuildInputs = [ finalAttrs.finalPackage ];
+        }
+        ''
+          set -o pipefail
+
+          # checking if 1 + 2 == 3.
+          if [[ "$(echo '{"a": 1, "b": 2}' | jaq 'add')" -eq 3 ]]; then
+            echo "test 1 passed"
+          else
+            echo "test 1 failed"
+            exit 1
+          fi
+
+          # echo out 0-3, map over them multiplying by 2, keep all elements under 5, add the results up together. Should be 6
+          if [[ "$(echo '[0, 1, 2, 3]' | jaq 'map(.*2) | [.[] | select(. < 5)] | add')" -eq 6 ]]; then
+            echo "test 2 passed"
+          else
+            echo "test 2 failed"
+            exit 1
+          fi
+
+          # fail on malformed input
+          if ! echo "0, 1, 4, " | jaq &>/dev/null; then
+            echo "test 3 passed"
+          else
+            echo "test 3 failed"
+            exit 1
+          fi
+
+          echo "All tests passed!"
+          touch $out
+        '';
+  };
 
   meta = {
     description = "Jq clone focused on correctness, speed and simplicity";