From 897a093a033ab5db192f351b091e417b92af4c57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Wed, 5 Jul 2023 11:52:13 +0200
Subject: [PATCH 01/10] Radically cleanup the templates
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Remove all the templates, except for one.
This makes the repository quite simpler, and emphasises the fact that we
want something that just works™

We'll certainly want to add some funkier tests, but in a more principled
way, and that doesn't leak into the end-user interface.

Also removes the example for the same reason
---
 .github/workflows/examples.yml                | 58 ------------
 .github/workflows/templates.yml               | 36 +-------
 examples/c-hello-world/flake.nix              | 14 ---
 examples/c-hello-world/hello.c                |  6 --
 examples/c-hello-world/nickel.lock.ncl        |  8 --
 examples/c-hello-world/package.ncl            | 29 ------
 flake.nix                                     | 90 ++-----------------
 templates/default/dev-shell.ncl               |  8 ++
 .../{devshells/clojure => default}/flake.nix  |  2 -
 .../{devshells/c => default}/nickel.lock.ncl  |  0
 templates/devshells/c/dev-shell.ncl           |  8 --
 templates/devshells/c/flake.nix               | 14 ---
 templates/devshells/clojure/dev-shell.ncl     |  8 --
 templates/devshells/clojure/nickel.lock.ncl   |  8 --
 templates/devshells/erlang/dev-shell.ncl      |  8 --
 templates/devshells/erlang/flake.nix          | 14 ---
 templates/devshells/erlang/nickel.lock.ncl    |  8 --
 templates/devshells/go/dev-shell.ncl          |  8 --
 templates/devshells/go/flake.nix              | 14 ---
 templates/devshells/go/nickel.lock.ncl        |  8 --
 templates/devshells/haskell/dev-shell.ncl     |  9 --
 templates/devshells/haskell/flake.nix         | 14 ---
 templates/devshells/haskell/nickel.lock.ncl   |  8 --
 templates/devshells/javascript/dev-shell.ncl  |  8 --
 templates/devshells/javascript/flake.nix      | 14 ---
 .../devshells/javascript/nickel.lock.ncl      |  8 --
 templates/devshells/php/dev-shell.ncl         |  8 --
 templates/devshells/php/flake.nix             | 14 ---
 templates/devshells/php/nickel.lock.ncl       |  8 --
 templates/devshells/python310/dev-shell.ncl   |  8 --
 templates/devshells/python310/flake.nix       | 14 ---
 templates/devshells/python310/nickel.lock.ncl |  8 --
 templates/devshells/racket/dev-shell.ncl      |  8 --
 templates/devshells/racket/flake.nix          | 14 ---
 templates/devshells/racket/nickel.lock.ncl    |  8 --
 templates/devshells/rust/create-env.sh        | 25 ------
 templates/devshells/rust/dev-shell.ncl        |  8 --
 templates/devshells/rust/flake.nix            | 14 ---
 templates/devshells/rust/nickel.lock.ncl      |  8 --
 templates/devshells/scala/dev-shell.ncl       |  8 --
 templates/devshells/scala/flake.nix           | 14 ---
 templates/devshells/scala/nickel.lock.ncl     |  8 --
 templates/devshells/zig/dev-shell.ncl         |  8 --
 templates/devshells/zig/flake.nix             | 14 ---
 templates/devshells/zig/nickel.lock.ncl       |  8 --
 test-template.sh                              | 38 ++++++++
 46 files changed, 58 insertions(+), 595 deletions(-)
 delete mode 100644 .github/workflows/examples.yml
 delete mode 100644 examples/c-hello-world/flake.nix
 delete mode 100644 examples/c-hello-world/hello.c
 delete mode 100644 examples/c-hello-world/nickel.lock.ncl
 delete mode 100644 examples/c-hello-world/package.ncl
 create mode 100644 templates/default/dev-shell.ncl
 rename templates/{devshells/clojure => default}/flake.nix (89%)
 rename templates/{devshells/c => default}/nickel.lock.ncl (100%)
 delete mode 100644 templates/devshells/c/dev-shell.ncl
 delete mode 100644 templates/devshells/c/flake.nix
 delete mode 100644 templates/devshells/clojure/dev-shell.ncl
 delete mode 100644 templates/devshells/clojure/nickel.lock.ncl
 delete mode 100644 templates/devshells/erlang/dev-shell.ncl
 delete mode 100644 templates/devshells/erlang/flake.nix
 delete mode 100644 templates/devshells/erlang/nickel.lock.ncl
 delete mode 100644 templates/devshells/go/dev-shell.ncl
 delete mode 100644 templates/devshells/go/flake.nix
 delete mode 100644 templates/devshells/go/nickel.lock.ncl
 delete mode 100644 templates/devshells/haskell/dev-shell.ncl
 delete mode 100644 templates/devshells/haskell/flake.nix
 delete mode 100644 templates/devshells/haskell/nickel.lock.ncl
 delete mode 100644 templates/devshells/javascript/dev-shell.ncl
 delete mode 100644 templates/devshells/javascript/flake.nix
 delete mode 100644 templates/devshells/javascript/nickel.lock.ncl
 delete mode 100644 templates/devshells/php/dev-shell.ncl
 delete mode 100644 templates/devshells/php/flake.nix
 delete mode 100644 templates/devshells/php/nickel.lock.ncl
 delete mode 100644 templates/devshells/python310/dev-shell.ncl
 delete mode 100644 templates/devshells/python310/flake.nix
 delete mode 100644 templates/devshells/python310/nickel.lock.ncl
 delete mode 100644 templates/devshells/racket/dev-shell.ncl
 delete mode 100644 templates/devshells/racket/flake.nix
 delete mode 100644 templates/devshells/racket/nickel.lock.ncl
 delete mode 100755 templates/devshells/rust/create-env.sh
 delete mode 100644 templates/devshells/rust/dev-shell.ncl
 delete mode 100644 templates/devshells/rust/flake.nix
 delete mode 100644 templates/devshells/rust/nickel.lock.ncl
 delete mode 100644 templates/devshells/scala/dev-shell.ncl
 delete mode 100644 templates/devshells/scala/flake.nix
 delete mode 100644 templates/devshells/scala/nickel.lock.ncl
 delete mode 100644 templates/devshells/zig/dev-shell.ncl
 delete mode 100644 templates/devshells/zig/flake.nix
 delete mode 100644 templates/devshells/zig/nickel.lock.ncl
 create mode 100755 test-template.sh

diff --git a/.github/workflows/examples.yml b/.github/workflows/examples.yml
deleted file mode 100644
index 0ec14174..00000000
--- a/.github/workflows/examples.yml
+++ /dev/null
@@ -1,58 +0,0 @@
-name: Examples
-
-on:
-  push:
-    branches:
-      - main
-  pull_request:
-
-jobs:
-
-  get-example-names:
-    name: Setup nix and nickel-nix
-    runs-on: ubuntu-latest
-
-    outputs:
-      examples: ${{ steps.examples.outputs.examples }}
-
-    steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 0
-
-    - name: Setup
-      uses: ./.github/actions/common-setup
-      with:
-        SECRET_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        CACHIX_TOKEN: ${{ secrets.CACHIX_TOKEN }}
-
-    - name: List all examples
-      id: examples
-      run: |
-        examples=$(python3 -c "import json, os, sys; json.dump(os.listdir('examples'), sys.stdout)")
-        echo "examples=$examples" >> $GITHUB_OUTPUT
-
-  test-examples:
-    name: Test example ${{ matrix.example }}
-    needs: get-example-names
-    runs-on: ubuntu-latest
-
-    strategy:
-      fail-fast: false
-      matrix:
-        example: ${{ fromJSON(needs.get-example-names.outputs.examples) }}
-
-    steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 0
-
-    - name: Setup
-      uses: ./.github/actions/common-setup
-      with:
-        SECRET_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        CACHIX_TOKEN: ${{ secrets.CACHIX_TOKEN }}
-
-    - name: Build
-      run: |
-        nix run .#tests.examples.${{ matrix.example }}
diff --git a/.github/workflows/templates.yml b/.github/workflows/templates.yml
index 90e6bc13..50f8ab6c 100644
--- a/.github/workflows/templates.yml
+++ b/.github/workflows/templates.yml
@@ -8,40 +8,10 @@ on:
 
 jobs:
 
-  get-template-names:
-    name: Setup nix and nickel-nix
-    runs-on: ubuntu-latest
-
-    outputs:
-      templates: ${{ steps.templates.outputs.templates }}
-
-    steps:
-    - uses: actions/checkout@v3
-      with:
-        fetch-depth: 0
-
-    - name: Setup
-      uses: ./.github/actions/common-setup
-      with:
-        SECRET_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        CACHIX_TOKEN: ${{ secrets.CACHIX_TOKEN }}
-
-    - name: List all templates
-      id: templates
-      run: |
-        templates=$(nix eval .#templates --apply builtins.attrNames --json)
-        echo "templates=$templates" >> $GITHUB_OUTPUT
-
   enter-devshells:
-    name: Test devshell ${{ matrix.template }}
-    needs: get-template-names
+    name: Test devshells
     runs-on: ubuntu-latest
 
-    strategy:
-      fail-fast: false
-      matrix:
-        template: ${{ fromJSON(needs.get-template-names.outputs.templates) }}
-
     steps:
     - uses: actions/checkout@v3
       with:
@@ -53,6 +23,6 @@ jobs:
         SECRET_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         CACHIX_TOKEN: ${{ secrets.CACHIX_TOKEN }}
 
-    - name: Test devshell ${{ matrix.template }}
+    - name: Test devshells
       run: |
-        nix run .#tests.templates.${{ matrix.template }}
+        nix develop --accept-flake-config --command bash test-template.sh
diff --git a/examples/c-hello-world/flake.nix b/examples/c-hello-world/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/examples/c-hello-world/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/examples/c-hello-world/hello.c b/examples/c-hello-world/hello.c
deleted file mode 100644
index 73e1b0a9..00000000
--- a/examples/c-hello-world/hello.c
+++ /dev/null
@@ -1,6 +0,0 @@
-#include <stdio.h>
-
-int main() {
-    printf("Hello, world!");
-    return 0;
-}
diff --git a/examples/c-hello-world/nickel.lock.ncl b/examples/c-hello-world/nickel.lock.ncl
deleted file mode 100644
index 3a95f954..00000000
--- a/examples/c-hello-world/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "/nix/store/qb3qvz3xxvnwy5ma1b60ba2gw8pw9vas-5626jyxg49xsax707lciippzazpldgjn-source/builders.ncl",
-    contracts = import "/nix/store/qb3qvz3xxvnwy5ma1b60ba2gw8pw9vas-5626jyxg49xsax707lciippzazpldgjn-source/contracts.ncl",
-
-    nix = import "/nix/store/qb3qvz3xxvnwy5ma1b60ba2gw8pw9vas-5626jyxg49xsax707lciippzazpldgjn-source/nix.ncl",
-  },
-}
diff --git a/examples/c-hello-world/package.ncl b/examples/c-hello-world/package.ncl
deleted file mode 100644
index 21783ad7..00000000
--- a/examples/c-hello-world/package.ncl
+++ /dev/null
@@ -1,29 +0,0 @@
-let nickel-nix = (import "./nickel.lock.ncl").nickel-nix in
-
-nickel-nix.builders.NixpkgsPkg & {
-  inputs_spec = {
-    bash.input = "nixpkgs",
-    coreutils.input = "nixpkgs",
-    gcc.input = "nixpkgs",
-  },
-
-  inputs,
-
-  output =
-    {
-      name = "hello",
-      version = "0.1",
-      structured_env = {
-        buildInputs.gcc = inputs.gcc,
-        buildInputs.coreutils = inputs.coreutils,
-        buildInputs.bash = inputs.bash,
-      },
-      env = {
-        buildCommand = nix-s%"
-          gcc %{nickel-nix.lib.import_file "hello.c"} -o hello
-          mkdir -p $out/bin
-          cp hello $out/bin/hello
-        "%,
-      },
-    }
-}
diff --git a/flake.nix b/flake.nix
index 246cf728..83309625 100644
--- a/flake.nix
+++ b/flake.nix
@@ -26,33 +26,17 @@
     topiary,
   } @ inputs:
     {
-      templates = let
-        inherit (nixpkgs) lib;
-        brokenShells = ["javascript" "php" "python310"];
-        filteredShells = (
-          lib.filterAttrs
-          (name: value: !(builtins.elem name brokenShells))
-          (builtins.readDir ./templates/devshells)
-        );
-      in
-        lib.mapAttrs'
-        (
-          name: value:
-            lib.nameValuePair
-            (name + "-devshell")
-            {
-              path = ./templates/devshells/${name};
-              description = "A ${name} devshell using nickel.";
-              welcomeText = ''
-                You have created a ${name} devshell that is built using nickel!
+      templates.default = {
+        path = ./templates/default;
+          description = "A devshell using nickel.";
+          welcomeText = ''
+            You have created a devshell that is built using nickel!
 
-                First run `nix run .#regenerate-lockfile` to fill `nickel.lock.ncl` with proper references.
+            First run `nix run .#regenerate-lockfile` to fill `nickel.lock.ncl` with proper references.
 
-                Then run `nix develop` to enter the dev shell.
-              '';
-            }
-        )
-        filteredShells;
+            Then run `nix develop` to enter the dev shell.
+          '';
+      };
 
       # Generate typical flake outputs from .ncl files in path for provided systems (default from flake-utils):
       #
@@ -158,62 +142,6 @@
           program = pkgs.lib.getExe (self.lib.${system}.buildLockFile contents);
         };
 
-        apps.tests = let
-          mkTest = {
-            name,
-            script,
-          }: let
-            test = pkgs.writeShellApplication {
-              inherit name;
-              text = ''
-                set -xeuo pipefail
-                WORKDIR=$(mktemp -d)
-                function clean() {
-                  rm -rf "''${WORKDIR}"
-                }
-                trap clean EXIT
-                cd "''${WORKDIR}"
-
-                ${script}
-              '';
-            };
-          in {
-            type = "app";
-            program = "${pkgs.lib.getExe test}";
-          };
-        in {
-          templates = pkgs.lib.flip pkgs.lib.mapAttrs self.templates (
-            name: _:
-              mkTest {
-                name = "test devshell ${name}";
-                script = ''
-                  nix flake new --template path:${self.outPath}#${name} example --accept-flake-config
-
-                  pushd ./example
-                  # We test against the local version of `nickel-nix`, not the one in main (hence the --override-input).
-                  nix flake lock --override-input nickel-nix path:${self.outPath} --accept-flake-config
-                  nix run .#regenerate-lockfile --accept-flake-config
-                  nix develop --accept-flake-config --print-build-logs < /dev/null
-                  popd
-                '';
-              }
-          );
-          examples = pkgs.lib.flip pkgs.lib.mapAttrs (builtins.readDir ./examples) (
-            name: _:
-              mkTest {
-                name = "test ${name}";
-                script = ''
-                  cp -r ${self.outPath}/examples/${name} ./${name}
-                  chmod -R u+w ./${name}
-                  cd ./${name}
-                  nix flake lock --override-input nickel-nix path:${self.outPath}
-                  nix run .#regenerate-lockfile --accept-flake-config
-                  nix build --accept-flake-config
-                '';
-              }
-          );
-        };
-
         devShells.default = pkgs.mkShell {
           packages = [
             inputs.nickel.packages."${system}".default
diff --git a/templates/default/dev-shell.ncl b/templates/default/dev-shell.ncl
new file mode 100644
index 00000000..f3453eaf
--- /dev/null
+++ b/templates/default/dev-shell.ncl
@@ -0,0 +1,8 @@
+let nixel = (import "./nickel.lock.ncl").nickel-nix in
+
+{
+  output = {
+    name = "nickel-shell",
+  }
+}
+& nixel.builders.BashShell
diff --git a/templates/devshells/clojure/flake.nix b/templates/default/flake.nix
similarity index 89%
rename from templates/devshells/clojure/flake.nix
rename to templates/default/flake.nix
index e0de00a6..dd4dd1aa 100644
--- a/templates/devshells/clojure/flake.nix
+++ b/templates/default/flake.nix
@@ -1,6 +1,4 @@
 {
-  description = "A basic flake with a shell";
-
   inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
   inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
 
diff --git a/templates/devshells/c/nickel.lock.ncl b/templates/default/nickel.lock.ncl
similarity index 100%
rename from templates/devshells/c/nickel.lock.ncl
rename to templates/default/nickel.lock.ncl
diff --git a/templates/devshells/c/dev-shell.ncl b/templates/devshells/c/dev-shell.ncl
deleted file mode 100644
index 2a2b2635..00000000
--- a/templates/devshells/c/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.CShell
diff --git a/templates/devshells/c/flake.nix b/templates/devshells/c/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/c/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/clojure/dev-shell.ncl b/templates/devshells/clojure/dev-shell.ncl
deleted file mode 100644
index a7cb7393..00000000
--- a/templates/devshells/clojure/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.ClojureShell
diff --git a/templates/devshells/clojure/nickel.lock.ncl b/templates/devshells/clojure/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/clojure/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/erlang/dev-shell.ncl b/templates/devshells/erlang/dev-shell.ncl
deleted file mode 100644
index 44922137..00000000
--- a/templates/devshells/erlang/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.ErlangShell
diff --git a/templates/devshells/erlang/flake.nix b/templates/devshells/erlang/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/erlang/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/erlang/nickel.lock.ncl b/templates/devshells/erlang/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/erlang/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/go/dev-shell.ncl b/templates/devshells/go/dev-shell.ncl
deleted file mode 100644
index 10e8e449..00000000
--- a/templates/devshells/go/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.GoShell
diff --git a/templates/devshells/go/flake.nix b/templates/devshells/go/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/go/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/go/nickel.lock.ncl b/templates/devshells/go/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/go/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/haskell/dev-shell.ncl b/templates/devshells/haskell/dev-shell.ncl
deleted file mode 100644
index 9e3837c2..00000000
--- a/templates/devshells/haskell/dev-shell.ncl
+++ /dev/null
@@ -1,9 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  ghcVersion = "927",
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.HaskellStackShell
diff --git a/templates/devshells/haskell/flake.nix b/templates/devshells/haskell/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/haskell/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/haskell/nickel.lock.ncl b/templates/devshells/haskell/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/haskell/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/javascript/dev-shell.ncl b/templates/devshells/javascript/dev-shell.ncl
deleted file mode 100644
index 00fccfcf..00000000
--- a/templates/devshells/javascript/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.JavascriptShell
diff --git a/templates/devshells/javascript/flake.nix b/templates/devshells/javascript/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/javascript/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/javascript/nickel.lock.ncl b/templates/devshells/javascript/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/javascript/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/php/dev-shell.ncl b/templates/devshells/php/dev-shell.ncl
deleted file mode 100644
index 86bcf759..00000000
--- a/templates/devshells/php/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.PhpShell
diff --git a/templates/devshells/php/flake.nix b/templates/devshells/php/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/php/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/php/nickel.lock.ncl b/templates/devshells/php/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/php/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/python310/dev-shell.ncl b/templates/devshells/python310/dev-shell.ncl
deleted file mode 100644
index d345d8b1..00000000
--- a/templates/devshells/python310/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.Python310Shell
diff --git a/templates/devshells/python310/flake.nix b/templates/devshells/python310/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/python310/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/python310/nickel.lock.ncl b/templates/devshells/python310/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/python310/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/racket/dev-shell.ncl b/templates/devshells/racket/dev-shell.ncl
deleted file mode 100644
index 78f70c1b..00000000
--- a/templates/devshells/racket/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.RacketShell
diff --git a/templates/devshells/racket/flake.nix b/templates/devshells/racket/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/racket/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/racket/nickel.lock.ncl b/templates/devshells/racket/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/racket/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/rust/create-env.sh b/templates/devshells/rust/create-env.sh
deleted file mode 100755
index 6a366827..00000000
--- a/templates/devshells/rust/create-env.sh
+++ /dev/null
@@ -1,25 +0,0 @@
-#!/usr/bin/env bash
-
-for devenv in $(awk '/= BashShell/ { print $1 }' ./nixel/builders.ncl)
-do
-  ENV_NAME="$(echo $devenv | tr [A-Z] [a-z] | sed 's/shell$//')"
-  DEST="../$ENV_NAME"
-  if ! [[ ./ -ef "$DEST" ]];
-  then
-    echo $ENV_NAME
-
-    rm -fr "$DEST"
-    mkdir -p "$DEST"
-    cp -r nixel flake.* "$DEST"
-
-    cat <<EOF > "${DEST}/dev-shell.ncl"
-let builders = import "nixel/builders.ncl" in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-} & builders.$devenv
-EOF
-  fi
-done
diff --git a/templates/devshells/rust/dev-shell.ncl b/templates/devshells/rust/dev-shell.ncl
deleted file mode 100644
index f140a714..00000000
--- a/templates/devshells/rust/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.RustShell
diff --git a/templates/devshells/rust/flake.nix b/templates/devshells/rust/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/rust/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/rust/nickel.lock.ncl b/templates/devshells/rust/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/rust/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/scala/dev-shell.ncl b/templates/devshells/scala/dev-shell.ncl
deleted file mode 100644
index 68f9cf74..00000000
--- a/templates/devshells/scala/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.ScalaShell
diff --git a/templates/devshells/scala/flake.nix b/templates/devshells/scala/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/scala/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/scala/nickel.lock.ncl b/templates/devshells/scala/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/scala/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/templates/devshells/zig/dev-shell.ncl b/templates/devshells/zig/dev-shell.ncl
deleted file mode 100644
index 1cf7efab..00000000
--- a/templates/devshells/zig/dev-shell.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-let builders = (import "./nickel.lock.ncl").nickel-nix.builders in
-
-{
-  output = {
-    name = "nickel-shell",
-  }
-}
-& builders.ZigShell
diff --git a/templates/devshells/zig/flake.nix b/templates/devshells/zig/flake.nix
deleted file mode 100644
index e0de00a6..00000000
--- a/templates/devshells/zig/flake.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  description = "A basic flake with a shell";
-
-  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
-  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
-
-  nixConfig = {
-    extra-substituters = ["https://nickel-nix.cachix.org"];
-    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
-  };
-
-  outputs = {nickel-nix, ...} @ inputs:
-    nickel-nix.flake.outputsFromNickel ./. inputs {};
-}
diff --git a/templates/devshells/zig/nickel.lock.ncl b/templates/devshells/zig/nickel.lock.ncl
deleted file mode 100644
index a8798724..00000000
--- a/templates/devshells/zig/nickel.lock.ncl
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  nickel-nix = {
-    builders = import "../../../builders.ncl",
-    contracts = import "../../../contracts.ncl",
-
-    nix = import "../../../nix.ncl",
-  },
-}
diff --git a/test-template.sh b/test-template.sh
new file mode 100755
index 00000000..3a100862
--- /dev/null
+++ b/test-template.sh
@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+set -xeuo pipefail
+
+test_one () {
+  target="$1"
+  PROJECT_ROOT=$PWD
+  WORKDIR=$(mktemp -d)
+  function clean() {
+    rm -rf "${WORKDIR}"
+  }
+  trap clean EXIT
+  pushd "${WORKDIR}"
+
+  nix flake new --template "path:$PROJECT_ROOT" example --accept-flake-config
+
+  pushd ./example
+  sed -i "s/Nickel/$target/" dev-shell.ncl
+  # We test against the local version of `nickel-nix`, not the one in main (hence the --override-input).
+  nix flake lock --override-input nickel-nix path:$PROJECT_ROOT --accept-flake-config
+  nix run .#regenerate-lockfile --accept-flake-config
+  nix develop --accept-flake-config --print-build-logs < /dev/null
+  popd
+  popd
+  clean
+}
+
+if [[ -n ${1+x} ]]; then
+  test_one "$1"
+else
+  all_targets=$(nickel export <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
+  for target in $all_targets; do
+    test_one $target
+  done
+fi
+
+
+target=${1:-Nickel}

From 056b02b668b628be77c3ad128eff5fd680633d74 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <7226587+thufschmitt@users.noreply.github.com>
Date: Wed, 5 Jul 2023 16:18:45 +0200
Subject: [PATCH 02/10] Use a working shell for the template

Co-authored-by: Yuriy Taraday <yuriy.taraday@tweag.io>
---
 test-template.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test-template.sh b/test-template.sh
index 3a100862..d71e2d0c 100755
--- a/test-template.sh
+++ b/test-template.sh
@@ -15,7 +15,7 @@ test_one () {
   nix flake new --template "path:$PROJECT_ROOT" example --accept-flake-config
 
   pushd ./example
-  sed -i "s/Nickel/$target/" dev-shell.ncl
+  sed -i "s/BashShell/$target/" dev-shell.ncl
   # We test against the local version of `nickel-nix`, not the one in main (hence the --override-input).
   nix flake lock --override-input nickel-nix path:$PROJECT_ROOT --accept-flake-config
   nix run .#regenerate-lockfile --accept-flake-config

From bb01493032a6d91863e6b5b25ccdeeb7bd54b1b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Wed, 5 Jul 2023 16:42:40 +0200
Subject: [PATCH 03/10] Fix the test-template script

---
 test-template.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test-template.sh b/test-template.sh
index d71e2d0c..528da901 100755
--- a/test-template.sh
+++ b/test-template.sh
@@ -28,7 +28,7 @@ test_one () {
 if [[ -n ${1+x} ]]; then
   test_one "$1"
 else
-  all_targets=$(nickel export <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
+  all_targets=$(nickel export --format raw <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
   for target in $all_targets; do
     test_one $target
   done

From 413e5833bf8de345f7c87b1d05772205cbae3267 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Wed, 5 Jul 2023 16:58:51 +0200
Subject: [PATCH 04/10] Make sure that all the shells work by default

Fix the broken ones and give default arguments to the ones that require
it.

Also blacklists `NickelPkg` as it's not a shell (arguably shouldn't be
in the same record as the shells, but that's a refactoring for later)
---
 lib/builders.ncl | 9 +--------
 test-template.sh | 3 +++
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/lib/builders.ncl b/lib/builders.ncl
index b485f1d5..ec89f866 100644
--- a/lib/builders.ncl
+++ b/lib/builders.ncl
@@ -166,15 +166,11 @@ in
     & {
       inputs_spec = {
         php = {},
-        intelephense = {
-          path = "nodePackages"."intelephense",
-        },
       },
       inputs,
 
       output.packages = {
         php = inputs.php,
-        intelephense = inputs.intelephense,
       },
     },
 
@@ -193,7 +189,6 @@ in
       },
     },
 
-  # nodePackages_latest.typescript-language-server is marked broken in nixpkgs
   JavascriptShell =
     BashShell
     & {
@@ -239,8 +234,6 @@ in
       },
     },
 
-  # broken: PyLTI-0.7.0 not supported for interpreter python3.10
-  # works with a regular nix shell though
   Python310Shell =
     BashShell
     & {
@@ -276,7 +269,7 @@ in
   HaskellStackShell =
     BashShell
     & {
-      ghcVersion, # User-defined. To keep in sync with the one used by stack
+      ghcVersion | default = "927", # User-defined. To keep in sync with the one used by stack
       inputs_spec = {
         stack = {},
         ormolu = {},
diff --git a/test-template.sh b/test-template.sh
index 528da901..082f93e6 100755
--- a/test-template.sh
+++ b/test-template.sh
@@ -30,6 +30,9 @@ if [[ -n ${1+x} ]]; then
 else
   all_targets=$(nickel export --format raw <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
   for target in $all_targets; do
+    if [[ "$target" == NickelPkg ]]; then
+      continue
+    fi
     test_one $target
   done
 fi

From 01066495bf60bedb972fcc956f08b9386bde51a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Wed, 5 Jul 2023 17:08:54 +0200
Subject: [PATCH 05/10] Expose the test script as an `app`

---
 flake.nix | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/flake.nix b/flake.nix
index 83309625..16658183 100644
--- a/flake.nix
+++ b/flake.nix
@@ -142,6 +142,21 @@
           program = pkgs.lib.getExe (self.lib.${system}.buildLockFile contents);
         };
 
+        apps.test.templates =
+          let testScript = pkgs.writeShellApplication {
+            name = "test-templates";
+            runtimeInputs = [ inputs.nickel.packages."${system}".nickel ];
+            text = ''
+              set -euo pipefail
+              cd ${./.}
+              exec ${pkgs.runtimeShell} ./test-template.sh "$@"
+            '';
+          }; in
+        {
+          type = "app";
+          program = pkgs.lib.getExe testScript;
+        };
+
         devShells.default = pkgs.mkShell {
           packages = [
             inputs.nickel.packages."${system}".default

From 2bf7686ed02f8836b169945b74b14130207ec93c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Wed, 5 Jul 2023 17:20:50 +0200
Subject: [PATCH 06/10] Remove a dead line of code

---
 test-template.sh | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/test-template.sh b/test-template.sh
index 082f93e6..ffb395e6 100755
--- a/test-template.sh
+++ b/test-template.sh
@@ -36,6 +36,3 @@ else
     test_one $target
   done
 fi
-
-
-target=${1:-Nickel}

From 2234606c3195c3be1574263112d2f8a1f3ef86ca Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Thu, 27 Jul 2023 07:10:27 +0200
Subject: [PATCH 07/10] Restore the example

---
 .github/workflows/templates.yml        |  3 +-
 examples/c-hello-world/flake.nix       | 14 +++++
 examples/c-hello-world/hello.c         |  6 ++
 examples/c-hello-world/nickel.lock.ncl |  8 +++
 examples/c-hello-world/package.ncl     | 29 +++++++++
 flake.nix                              |  6 +-
 run-test.sh                            | 83 ++++++++++++++++++++++++++
 test-template.sh                       | 38 ------------
 8 files changed, 145 insertions(+), 42 deletions(-)
 create mode 100644 examples/c-hello-world/flake.nix
 create mode 100644 examples/c-hello-world/hello.c
 create mode 100644 examples/c-hello-world/nickel.lock.ncl
 create mode 100644 examples/c-hello-world/package.ncl
 create mode 100755 run-test.sh
 delete mode 100755 test-template.sh

diff --git a/.github/workflows/templates.yml b/.github/workflows/templates.yml
index 50f8ab6c..05e01917 100644
--- a/.github/workflows/templates.yml
+++ b/.github/workflows/templates.yml
@@ -25,4 +25,5 @@ jobs:
 
     - name: Test devshells
       run: |
-        nix develop --accept-flake-config --command bash test-template.sh
+        nix develop --accept-flake-config --command bash run-test.sh template
+        nix develop --accept-flake-config --command bash run-test.sh example examples/c-hello-world
diff --git a/examples/c-hello-world/flake.nix b/examples/c-hello-world/flake.nix
new file mode 100644
index 00000000..e0de00a6
--- /dev/null
+++ b/examples/c-hello-world/flake.nix
@@ -0,0 +1,14 @@
+{
+  description = "A basic flake with a shell";
+
+  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";
+  inputs.nickel-nix.url = "github:nickel-lang/nickel-nix";
+
+  nixConfig = {
+    extra-substituters = ["https://nickel-nix.cachix.org"];
+    extra-trusted-public-keys = ["nickel-nix.cachix.org-1:/Ziozgt3g0CfGwGS795wyjRa9ArE89s3tbz31S6xxFM="];
+  };
+
+  outputs = {nickel-nix, ...} @ inputs:
+    nickel-nix.flake.outputsFromNickel ./. inputs {};
+}
diff --git a/examples/c-hello-world/hello.c b/examples/c-hello-world/hello.c
new file mode 100644
index 00000000..73e1b0a9
--- /dev/null
+++ b/examples/c-hello-world/hello.c
@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main() {
+    printf("Hello, world!");
+    return 0;
+}
diff --git a/examples/c-hello-world/nickel.lock.ncl b/examples/c-hello-world/nickel.lock.ncl
new file mode 100644
index 00000000..3a95f954
--- /dev/null
+++ b/examples/c-hello-world/nickel.lock.ncl
@@ -0,0 +1,8 @@
+{
+  nickel-nix = {
+    builders = import "/nix/store/qb3qvz3xxvnwy5ma1b60ba2gw8pw9vas-5626jyxg49xsax707lciippzazpldgjn-source/builders.ncl",
+    contracts = import "/nix/store/qb3qvz3xxvnwy5ma1b60ba2gw8pw9vas-5626jyxg49xsax707lciippzazpldgjn-source/contracts.ncl",
+
+    nix = import "/nix/store/qb3qvz3xxvnwy5ma1b60ba2gw8pw9vas-5626jyxg49xsax707lciippzazpldgjn-source/nix.ncl",
+  },
+}
diff --git a/examples/c-hello-world/package.ncl b/examples/c-hello-world/package.ncl
new file mode 100644
index 00000000..21783ad7
--- /dev/null
+++ b/examples/c-hello-world/package.ncl
@@ -0,0 +1,29 @@
+let nickel-nix = (import "./nickel.lock.ncl").nickel-nix in
+
+nickel-nix.builders.NixpkgsPkg & {
+  inputs_spec = {
+    bash.input = "nixpkgs",
+    coreutils.input = "nixpkgs",
+    gcc.input = "nixpkgs",
+  },
+
+  inputs,
+
+  output =
+    {
+      name = "hello",
+      version = "0.1",
+      structured_env = {
+        buildInputs.gcc = inputs.gcc,
+        buildInputs.coreutils = inputs.coreutils,
+        buildInputs.bash = inputs.bash,
+      },
+      env = {
+        buildCommand = nix-s%"
+          gcc %{nickel-nix.lib.import_file "hello.c"} -o hello
+          mkdir -p $out/bin
+          cp hello $out/bin/hello
+        "%,
+      },
+    }
+}
diff --git a/flake.nix b/flake.nix
index 16658183..7346d3ac 100644
--- a/flake.nix
+++ b/flake.nix
@@ -142,14 +142,14 @@
           program = pkgs.lib.getExe (self.lib.${system}.buildLockFile contents);
         };
 
-        apps.test.templates =
+        apps.run-test =
           let testScript = pkgs.writeShellApplication {
             name = "test-templates";
-            runtimeInputs = [ inputs.nickel.packages."${system}".nickel ];
+            runtimeInputs = [ inputs.nickel.packages."${system}".nickel-lang-cli ];
             text = ''
               set -euo pipefail
               cd ${./.}
-              exec ${pkgs.runtimeShell} ./test-template.sh "$@"
+              exec ${pkgs.runtimeShell} ./run-test.sh "$@"
             '';
           }; in
         {
diff --git a/run-test.sh b/run-test.sh
new file mode 100755
index 00000000..5627dc34
--- /dev/null
+++ b/run-test.sh
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+
+set -xeuo pipefail
+
+usage() {
+  cat <<EOF
+Usage:
+
+$0 template <shellName> -- test instantiating the template using the given shell
+$0 example <examplePath> -- Try running the example at <examplePath>
+EOF
+  exit 1
+}
+
+pushd_temp () {
+  WORKDIR=$(mktemp -d)
+  function clean() {
+    rm -rf "${WORKDIR}"
+  }
+  trap clean EXIT
+  pushd "${WORKDIR}"
+}
+
+prepare_shell() {
+  # We test against the local version of `nickel-nix`, not the one in main (hence the --override-input).
+  nix flake lock --override-input nickel-nix path:$PROJECT_ROOT --accept-flake-config
+  nix run .#regenerate-lockfile --accept-flake-config
+}
+
+# Note: running in a subshell (hence the parens and not braces around the function body) so that the trap-based cleanup happens whenever we exit
+test_one_template () (
+  target="$1"
+  pushd_temp
+
+  nix flake new --template "path:$PROJECT_ROOT" example --accept-flake-config
+
+  pushd ./example
+  sed -i "s/BashShell/$target/" dev-shell.ncl
+  prepare_shell
+  nix develop --accept-flake-config --print-build-logs < /dev/null
+  popd
+  popd
+  clean
+)
+
+test_template () {
+  if [[ -n ${1+x} ]]; then
+    test_one_template "$1"
+  else
+    all_targets=$(nickel export --format raw <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
+    for target in $all_targets; do
+      if [[ "$target" == NickelPkg ]] || [[ "$target" == "NixpkgsPkg" ]]; then
+        continue
+      fi
+      test_one_template $target
+    done
+  fi
+}
+
+test_example () (
+  examplePath=$(realpath "$1")
+  pushd_temp
+  cp -r "$examplePath" .
+  pushd *
+  prepare_shell
+  nix build --print-build-logs
+  popd
+  popd
+)
+
+PROJECT_ROOT=$PWD
+
+if [[ -z ${1+x} ]]; then
+  usage
+elif [[ $1 == "template" ]]; then
+  shift
+  test_template "$@"
+elif [[ $1 == "example" ]]; then
+  shift
+  test_example "$@"
+else
+  usage
+fi
diff --git a/test-template.sh b/test-template.sh
deleted file mode 100755
index ffb395e6..00000000
--- a/test-template.sh
+++ /dev/null
@@ -1,38 +0,0 @@
-#!/usr/bin/env bash
-
-set -xeuo pipefail
-
-test_one () {
-  target="$1"
-  PROJECT_ROOT=$PWD
-  WORKDIR=$(mktemp -d)
-  function clean() {
-    rm -rf "${WORKDIR}"
-  }
-  trap clean EXIT
-  pushd "${WORKDIR}"
-
-  nix flake new --template "path:$PROJECT_ROOT" example --accept-flake-config
-
-  pushd ./example
-  sed -i "s/BashShell/$target/" dev-shell.ncl
-  # We test against the local version of `nickel-nix`, not the one in main (hence the --override-input).
-  nix flake lock --override-input nickel-nix path:$PROJECT_ROOT --accept-flake-config
-  nix run .#regenerate-lockfile --accept-flake-config
-  nix develop --accept-flake-config --print-build-logs < /dev/null
-  popd
-  popd
-  clean
-}
-
-if [[ -n ${1+x} ]]; then
-  test_one "$1"
-else
-  all_targets=$(nickel export --format raw <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
-  for target in $all_targets; do
-    if [[ "$target" == NickelPkg ]]; then
-      continue
-    fi
-    test_one $target
-  done
-fi

From e2df93d098d8e4ef6b7ddc96cfa1b16b04d1d53e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Thu, 27 Jul 2023 16:35:19 +0200
Subject: [PATCH 08/10] Use `nix run` for the tests

---
 .github/workflows/templates.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/templates.yml b/.github/workflows/templates.yml
index 05e01917..6b5fd5b9 100644
--- a/.github/workflows/templates.yml
+++ b/.github/workflows/templates.yml
@@ -25,5 +25,5 @@ jobs:
 
     - name: Test devshells
       run: |
-        nix develop --accept-flake-config --command bash run-test.sh template
-        nix develop --accept-flake-config --command bash run-test.sh example examples/c-hello-world
+        nix run .#run-test template
+        nix run .#run-test example examples/c-hello-world

From 8deaa421be7008845a4cd6dbb06b2e28de47be3f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Thu, 27 Jul 2023 20:54:59 +0200
Subject: [PATCH 09/10] Don't cd in the flake dir when running the tests

Let the user do it, and benefit from the shellcheck of `writeShellApplication`.
---
 flake.nix   | 6 +-----
 run-test.sh | 8 ++++----
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/flake.nix b/flake.nix
index 7346d3ac..e97682b4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -146,11 +146,7 @@
           let testScript = pkgs.writeShellApplication {
             name = "test-templates";
             runtimeInputs = [ inputs.nickel.packages."${system}".nickel-lang-cli ];
-            text = ''
-              set -euo pipefail
-              cd ${./.}
-              exec ${pkgs.runtimeShell} ./run-test.sh "$@"
-            '';
+            text = builtins.readFile ./run-test.sh;
           }; in
         {
           type = "app";
diff --git a/run-test.sh b/run-test.sh
index 5627dc34..9604fa36 100755
--- a/run-test.sh
+++ b/run-test.sh
@@ -23,7 +23,7 @@ pushd_temp () {
 
 prepare_shell() {
   # We test against the local version of `nickel-nix`, not the one in main (hence the --override-input).
-  nix flake lock --override-input nickel-nix path:$PROJECT_ROOT --accept-flake-config
+  nix flake lock --override-input nickel-nix "path:$PROJECT_ROOT" --accept-flake-config
   nix run .#regenerate-lockfile --accept-flake-config
 }
 
@@ -47,12 +47,12 @@ test_template () {
   if [[ -n ${1+x} ]]; then
     test_one_template "$1"
   else
-    all_targets=$(nickel export --format raw <<<'std.record.fields (import "builders.ncl") |> std.string.join " "')
+    all_targets=$(nickel export --format raw <<<'std.record.fields ((import "lib/nix.ncl").builders) |> std.string.join " "')
     for target in $all_targets; do
       if [[ "$target" == NickelPkg ]] || [[ "$target" == "NixpkgsPkg" ]]; then
         continue
       fi
-      test_one_template $target
+      test_one_template "$target"
     done
   fi
 }
@@ -61,7 +61,7 @@ test_example () (
   examplePath=$(realpath "$1")
   pushd_temp
   cp -r "$examplePath" .
-  pushd *
+  pushd ./*
   prepare_shell
   nix build --print-build-logs
   popd

From 719acd19e559bf18791b9ab9cc8bbce87f4dc30b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophane=20Hufschmitt?=
 <theophane.hufschmitt@tweag.io>
Date: Thu, 27 Jul 2023 20:55:47 +0200
Subject: [PATCH 10/10] Avoid a fishy `pushd *`

---
 run-test.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/run-test.sh b/run-test.sh
index 9604fa36..98aa502b 100755
--- a/run-test.sh
+++ b/run-test.sh
@@ -60,8 +60,8 @@ test_template () {
 test_example () (
   examplePath=$(realpath "$1")
   pushd_temp
-  cp -r "$examplePath" .
-  pushd ./*
+  cp -r "$examplePath" ./example
+  pushd ./example
   prepare_shell
   nix build --print-build-logs
   popd