WIP

bin/flake_env.re

@@ -1,149 +1,55 @@
 open Core;
 module Unix = Core_unix;
 
+open Lib;
 
-let preflight = (layout_directory) => {
-  switch (Lib.Versions.preflight_versions(), Sys_unix.is_directory(layout_directory)) {
-    | (Ok(_), `Yes) => Ok()
-    | (Ok(_), _) => {
-      Unix.mkdir_p(layout_directory);
-      Ok()
-    }
-    | (err, _) => err
-  }
-}
-
-let hash_files = (filenames) => {
-  let ctx = Sha1.init();
-  let () = filenames
-  |> Array.filter(~f=f => switch (Sys_unix.file_exists(f)) {
-      | `Yes => true
-      | _ => false
-    })
-  |> Array.iter(~f=(f) => {
-    f |> In_channel.create |> In_channel.input_all |> Sha1.update_string(ctx);
-  });
-  Sha1.finalize(ctx) |> Sha1.to_hex
-};
-
-// TODO: Maybe make this more terse?
-let rec rmrf = (path) => {
-  switch (Unix.lstat(path).st_kind) {
-  | exception Unix.Unix_error(_, _, _) => ()
-  | S_REG => Unix.unlink(path)
-  | S_LNK => Unix.unlink(path)
-  | S_DIR => {
-      Sys_unix.readdir(path) |> Array.iter(~f=name => rmrf(Filename.concat(path, name)));
-      Unix.rmdir(path)
-    }
-  | S_CHR => Printf.eprintf("Don't know how to handle Character Device file\n")
-  | S_BLK => Printf.eprintf("Don't know how to handle Block Device file\n")
-  | S_FIFO => Printf.eprintf("Don't know how to handle FIFO file\n")
-  | S_SOCK => Printf.eprintf("Don't know how to handle Socket file\n")
-  }
-};
-
-let clean_old_gcroots = (layout_dir) => {
-  rmrf(layout_dir ++ "/flake-inputs/");
-  rmrf(layout_dir);
-  Unix.mkdir_p(layout_dir ++ "/flake-inputs/");
-};
-
-let print_cur_cache = (profile_rc) => {
-  In_channel.read_all(profile_rc) |> Printf.printf("%s")
-};
-
-let add_gcroot = (store_path, symlink) => {
-  switch (Lib.Util.nix(["build", "--out-link", symlink, store_path])) {
-  | (Ok(), _) => Ok()
-  | (err, _) => err
-  }
-}
-
-let freshen_cache = (layout_dir, hash, flake_specifier) => {
-  clean_old_gcroots(layout_dir);
-  let tmp_profile = layout_dir ++ "flake-tmp-profile."  ++ Core.Pid.to_string(Core_unix.getpid());
-  let (exit_code, stdout_content) = Lib.Util.nix(["print-dev-env", "--profile", tmp_profile, flake_specifier]);
-
-  let profile = layout_dir ++ "/flake-profile-" ++ hash;
-  let profile_rc = profile ++ ".rc";
-
-  switch (exit_code) {
-  | Ok() => {
-      Out_channel.with_file(~f=f=> Out_channel.output_string(f, stdout_content), profile_rc);
-      switch (add_gcroot(tmp_profile, profile)) {
-        | Ok() => {
-          Sys_unix.remove(tmp_profile);
-          let flake_input_cache_path = layout_dir ++ "/flake-inputs/"
-          let flake_inputs = Lib.Watches.get_input_paths();
-          flake_inputs |> List.iter(~f=(inpt) => {
-            switch (add_gcroot("/nix/store/" ++ inpt, flake_input_cache_path ++ inpt)) {
-            | Ok() => ()
-            | err => Printf.eprintf("Failed creating flake-input gcroot: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
-            };
-          });
-          print_cur_cache(profile_rc);
-        }
-        | err => {
-          Printf.eprintf("Failed creating gcroot: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
-          exit(1);
-        }
-      };
-    }
-  | err => {
-      Printf.eprintf("Failed evaluating flake: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
-      exit(1);
-    }
-  };
-
-};
-
-// TODO: Extend to add support for additional flags, maybe?
 let main = () => {
   let argv = Sys.get_argv();
-  switch (Array.length(argv)) {
+  switch (Util.get_args(argv)) {
-  | 3 => {
+  | Ok((layout_directory, flake_specifier, other_args)) => {
-      let flake_specifier = argv[1];
-      let layout_directory = argv[2];
       switch (preflight(layout_directory)) {
-        | Ok() => {
+      | Ok() => {
-            switch (Lib.Watches.get()) {
+          switch (Lib.Watches.get()) {
-            | Ok(watches) => {
+          | Ok(watches) => {
-                let paths = Array.map(~f=watch => watch.path, watches);
+              let paths = Array.map(~f=watch => watch.path, watches);
-                let hash = hash_files(paths);
+              let hash = Util.hash_files(paths);
-                let profile = layout_directory ++ "/flake-profile-" ++ hash;
+              let profile = layout_directory ++ "/flake-profile-" ++ hash;
-                let profile_rc = profile ++ ".rc";
+              let profile_rc = profile ++ ".rc";
 
-                switch ((Sys_unix.is_file(profile_rc), Sys_unix.is_file(profile))) {
+              switch ((Sys_unix.is_file(profile_rc), Sys_unix.is_file(profile))) {
-                | (`Yes, `Yes) => {
+              | (`Yes, `Yes) => {
-                    let profile_rc_mtime = Unix.stat(profile_rc).st_mtime;
+                  let profile_rc_mtime = Unix.stat(profile_rc).st_mtime;
-                    let all_older= Array.map(~f=watch => watch.modtime, watches)
+                  let all_older = Array.map(
-                    |> Array.for_all(~f=watch_mtime => watch_mtime <= int_of_float(profile_rc_mtime))
+                    ~f=watch => watch.modtime, watches)
-                    switch (all_older) {
+                  |> Array.for_all(
-                    | true => print_cur_cache(profile_rc)
+                      ~f=watch_mtime => watch_mtime <= int_of_float(profile_rc_mtime)
-                    | false => freshen_cache(layout_directory, hash, flake_specifier)
+                    )
-                    }
+                  if (all_older) {
+                    print_cur_cache(profile_rc)
+                  } else {
+                    freshen_cache(layout_directory, hash, flake_specifier, other_args)
                   }
-                | _ => freshen_cache(layout_directory, hash, flake_specifier)
                 }
-              };
+              | _ => freshen_cache(layout_directory, hash, flake_specifier, other_args)
-            | Error(e) => {
-                Printf.eprintf("%s\n", e);
-                exit(1);
               }
+            };
+          | Error(e) => {
+              Printf.eprintf("%s\n", e);
+              exit(1);
             }
           }
+        }
       | Error(e) => {
           Printf.eprintf("%s\n", e);
           exit(1);
         }
       };
     }
-  | _ => {
+  | Error() => {
-      Printf.eprintf("%s <flake specifier> <layout_directory>\n", argv[0]);
+      Printf.eprintf("%s  <layout_directory> <flake specifier> <...args>\n", argv[0]);
       exit(1);
-      }
+    }
   }
-}
+};
 
 let () = main();

default.nix

@@ -2,6 +2,7 @@
 , core
 , core_unix
 , findlib
+, fmt
 , lib
 , nix-filter
 , ocaml
@@ -41,6 +42,7 @@ buildDunePackage {
     core
     core_unix
     findlib
+    fmt
     ocaml
     ppx_yojson_conv
     ppx_yojson_conv_lib

direnvrc

@@ -41,7 +41,7 @@ use_flake_env() {
   local ld=$(direnv_layout_dir)
   export direnv
 
-  eval "$(@flake_env@ "$1" "$ld")"
+  eval "$(@flake_env@ "$ld" "$@")"
 
   export -n direnv
 

flake.nix

@@ -29,6 +29,8 @@
           devShells.default = pkgs.mkShell {
             inputsFrom = [ self'.packages.default ];
             packages = [
+              pkgs.ocamlPackages.alcotest
+              pkgs.ocamlPackages.bisect_ppx
               pkgs.ocamlPackages.dune_3
               pkgs.ocamlPackages.findlib
               pkgs.ocamlPackages.ocaml

lib/#flake_env__versions.re#

@@ -0,0 +1,81 @@
+open Core;
+module Unix = Core_unix;
+
+module Util = Flake_env__util;
+
+
+type t = {
+  major: int,
+  minor: int,
+  point: int,
+};
+
+let init = (major, minor, point) => {
+  {major, minor, point}
+};
+
+let required_direnv_version = init(2, 21, 3);
+
+let required_nix_version = init(2, 10, 0);
+
+let semver_re = Re.compile(Re.Posix.re({|([0-9]+)\.([0-9]+)\.([0-9]+)|}));
+
+let compare = (a, b) => {
+  switch (a, b) {
+  | (a, b) when a.major == b.major && a.minor == b.minor && a.point == b.point => 0
+  | (a, b) when a.major < b.major => -1
+  | (a, b) when a.major == b.major && a.minor < b.minor => -1
+  | (a, b) when a.major == b.major && a.minor == b.minor && a.point < b.point => -1
+  | _ => 1
+  }
+}
+
+let extract_version_number = (cmd) => {
+  switch (Util.run_process(cmd, ["--version"])) {
+  | (Ok(), stdout)  when String.length(stdout) > 0 => {
+      let substrings = Re.exec(semver_re, stdout);
+      let groups = Re.Group.all(substrings);
+      if ((groups |> Array.length) == 4) {
+        Ok({
+          major: groups[1] |> int_of_string,
+          minor: groups[2] |> int_of_string,
+          point: groups[3] |> int_of_string
+        })
+      } else {
+        Error(Printf.sprintf("Stdout did not contain a version number for `%s --version`", cmd))
+      }
+    }
+    | _ => Error(Printf.sprintf("Failed executing '%s'\n", cmd))
+  }
+};
+
+let is_new_enough = (cur, needed) => {
+  switch (cur) {
+    | Ok(cur) => {
+        switch (compare(cur, needed)) {
+        | x when x < 0 => Ok(false)
+        | _ => Ok(true)
+        }
+      }
+    | Error(e) => Error(e)
+  }
+};
+
+let in_direnv = () => switch (Sys.getenv("direnv")) {
+    | Some(_) => true
+    | None => false
+};
+
+let preflight_versions = () => {
+  let is_nix_new_enough = is_new_enough(extract_version_number("nix"), required_nix_version);
+  let is_direnv_new_enough = is_new_enough(extract_version_number("direnv"), required_direnv_version);
+
+  switch (in_direnv(), is_direnv_new_enough, is_nix_new_enough) {
+    | (false, _, _) => Error("Not in direnv!")
+    | (_, Ok(false), _) => Error("Direnv version is not new enough")
+    | (_, _, Ok(false)) => Error("Nix version is not new enough")
+    | (_, Error(e), _) => Error(e)
+    | (_, _, Error(e)) => Error(e)
+    | (true, Ok(true), Ok(true)) => Ok()
+  }
+};

lib/dune

@@ -1,5 +1,14 @@
 (library
   (name lib)
   (public_name flake_env.lib)
-  (libraries core core_unix core_unix.filename_unix core_unix.sys_unix ppx_yojson_conv re sha)
+  (libraries
+    core
+    core_unix
+    core_unix.filename_unix
+    core_unix.sys_unix
+    fmt
+    ppx_yojson_conv
+    re
+    sha)
+  (instrumentation (backend bisect_ppx))
   (preprocess (pps ppx_yojson_conv ppx_jane ppx_inline_test)))

lib/flake_env__util.re

@@ -1,10 +1,55 @@
 open Core;
 module Unix = Core_unix;
 
-let nix = (args) => {
+let run_process = (name, args) => {
-  let stdout_chan = Unix.open_process_in(
+  /*** Run a process [name] with args [args], returning (exit_code, stdout text) */
-    "nix --extra-experimental-features \"nix-command flakes\" " ++ (args |> String.concat(~sep=" ")));
+  let stdout_chan = Unix.open_process_in(name ++ " " ++ (args |> String.concat(~sep=" ")));
   let stdout_content = stdout_chan |> In_channel.input_all;
   let exit_code = Unix.close_process_in(stdout_chan);
   (exit_code, stdout_content)
-}
+ };
+
+let nix = (args) => run_process("nix", ["--extra-experimental-features", "\"nix-command flakes\" ", ...args]);
+
+let hash_files = (filenames) => {
+  /*** Hash all entries in [filenames], returning a hex-encoded string of the hash of their contents */
+  let ctx = Sha1.init();
+  let () = filenames
+  |> Array.filter(~f=f => switch (Sys_unix.file_exists(f)) {
+      | `Yes => true
+      | _ => false
+    })
+  |> Array.iter(~f=(f) => {
+      f |> In_channel.create |> In_channel.input_all |> Sha1.update_string(ctx);
+    });
+  Sha1.finalize(ctx) |> Sha1.to_hex
+};
+
+let rec rmrf = (path) => {
+  switch (Unix.lstat(path).st_kind) {
+  | exception Unix.Unix_error(_, _, _) => ()
+  | S_REG => Unix.unlink(path)
+  | S_LNK => Unix.unlink(path)
+  | S_DIR => {
+      Sys_unix.readdir(path) |> Array.iter(~f=name => rmrf(Filename.concat(path, name)));
+      Unix.rmdir(path)
+    }
+  | S_CHR => Printf.eprintf("Don't know how to handle Character Device file\n")
+  | S_BLK => Printf.eprintf("Don't know how to handle Block Device file\n")
+  | S_FIFO => Printf.eprintf("Don't know how to handle FIFO file\n")
+  | S_SOCK => Printf.eprintf("Don't know how to handle Socket file\n")
+  }
+};
+
+let get_args = (argv) => {
+  switch (Array.length(argv)) {
+  | x when x >= 3 => {
+      let layout_directory = argv[1];
+      let flake_specifier = argv[2];
+      let other_args = snd(List.split_n(List.of_array(argv), 3));
+      Ok((layout_directory, flake_specifier, other_args))
+    }
+  | _ => Error()
+  }
+};
+

lib/flake_env__versions.re

@@ -1,28 +1,28 @@
 open Core;
 module Unix = Core_unix;
 
+module Util = Flake_env__util;
+
+
 type t = {
   major: int,
   minor: int,
   point: int,
 };
 
+let init = (major, minor, point) => {
+  {major, minor, point}
+};
+
+let required_direnv_version = init(2, 21, 3);
+
+let required_nix_version = init(2, 10, 0);
+
 let semver_re = Re.compile(Re.Posix.re({|([0-9]+)\.([0-9]+)\.([0-9]+)|}));
 
-let required_direnv_version = {
+let pprint = (pp_fmt, version) => Fmt.pf(pp_fmt, "{ major: %d, minor: %d, point: %d }", version.major, version.minor, version.point);
-  major: 2,
-  minor: 21,
-  point: 3
-};
 
-let required_nix_version = {
+let compare = (a, b) => {
-  major: 2,
-  minor: 10,
-  point: 0
-};
-
-// TODO: test this
-let compare_version_number = (a, b) => {
   switch (a, b) {
   | (a, b) when a.major == b.major && a.minor == b.minor && a.point == b.point => 0
   | (a, b) when a.major < b.major => -1
@@ -32,46 +32,47 @@ let compare_version_number = (a, b) => {
   }
 }
 
-let%test_unit "compare_version_number" = [%test_eq: int](compare_version_number({major: 1, minor: 0, point: 0}, {major: 2, minor: 0, point: 0}), -1);
-
 let extract_version_number = (cmd) => {
-  let full_cmd = cmd ++ " --version";
+  switch (Util.run_process(cmd, ["--version"])) {
-  switch (Core_unix.open_process_in(full_cmd) |> In_channel.input_line) {
+  | (Ok(), stdout)  when String.length(stdout) > 0 => {
-  | Some(stdout) => {
       let substrings = Re.exec(semver_re, stdout);
       let groups = Re.Group.all(substrings);
-      Ok({
+      if ((groups |> Array.length) == 4) {
-        major: groups[1] |> int_of_string,
+        Ok({
-        minor: groups[2] |> int_of_string,
+          major: groups[1] |> int_of_string,
-        point: groups[3] |> int_of_string
+          minor: groups[2] |> int_of_string,
-      })
+          point: groups[3] |> int_of_string
+        })
+      } else {
+        Error(Printf.sprintf("Stdout did not contain a version number for `%s --version`", cmd))
+      }
     }
-  | None => Error(Printf.sprintf("Failed executing '%s'\n", cmd))
+    | _ => Error(Printf.sprintf("Failed executing '%s'\n", cmd))
   }
 };
 
-let is_version_new_enough = (cur, needed) => {
+let is_new_enough = (cur, needed) => {
   switch (cur) {
     | Ok(cur) => {
-        switch (compare_version_number(cur, needed)) {
+        switch (compare(cur, needed)) {
         | x when x < 0 => Ok(false)
         | _ => Ok(true)
         }
       }
     | Error(e) => Error(e)
   }
-}
+};
 
-let preflight_versions = () => {
+let in_direnv = () => switch (Sys.getenv("direnv")) {
-  let in_direnv = switch (Sys.getenv("direnv")) {
     | Some(_) => true
     | None => false
-  };
+};
 
-  let is_nix_new_enough = is_version_new_enough(extract_version_number("nix"), required_nix_version);
+let preflight_versions = () => {
-  let is_direnv_new_enough = is_version_new_enough(extract_version_number("direnv"), required_direnv_version);
+  let is_nix_new_enough = is_new_enough(extract_version_number("nix"), required_nix_version);
+  let is_direnv_new_enough = is_new_enough(extract_version_number("direnv"), required_direnv_version);
 
-  switch (in_direnv, is_direnv_new_enough, is_nix_new_enough) {
+  switch (in_direnv(), is_direnv_new_enough, is_nix_new_enough) {
     | (false, _, _) => Error("Not in direnv!")
     | (_, Ok(false), _) => Error("Direnv version is not new enough")
     | (_, _, Ok(false)) => Error("Nix version is not new enough")

lib/lib.re

@@ -1,3 +1,73 @@
+open Core;
+module Unix = Core_unix;
+
 module Util = Flake_env__util;
 module Watches = Flake_env__watches;
 module Versions = Flake_env__versions;
+
+let print_cur_cache = (profile_rc) => {
+  In_channel.read_all(profile_rc) |> Printf.printf("%s")
+};
+
+let clean_old_gcroots = (layout_dir) => {
+  Util.rmrf(layout_dir ++ "/flake-inputs/");
+  Util.rmrf(layout_dir);
+  Unix.mkdir_p(layout_dir ++ "/flake-inputs/");
+};
+
+let add_gcroot = (store_path, symlink) => {
+  switch (Util.nix(["build", "--out-link", symlink, store_path])) {
+  | (Ok(), _) => Ok()
+  | (err, _) => err
+  }
+};
+
+let freshen_cache = (layout_dir, hash, flake_specifier, other_args) => {
+    clean_old_gcroots(layout_dir);
+    let tmp_profile = layout_dir ++ "flake-tmp-profile."  ++ Core.Pid.to_string(Core_unix.getpid());
+
+    let pde_args = ["print-dev-env", "--profile", tmp_profile, flake_specifier, ...other_args];
+    let (exit_code, stdout_content) = Util.nix(pde_args);
+
+    let profile = layout_dir ++ "/flake-profile-" ++ hash;
+    let profile_rc = profile ++ ".rc";
+
+    switch (exit_code) {
+    | Ok() => {
+        Out_channel.with_file(~f=f=> Out_channel.output_string(f, stdout_content), profile_rc);
+        switch (add_gcroot(tmp_profile, profile)) {
+        | Ok() => {
+            Sys_unix.remove(tmp_profile);
+            let flake_input_cache_path = layout_dir ++ "/flake-inputs/"
+              let flake_inputs = Watches.get_input_paths();
+            flake_inputs |> List.iter(~f=(inpt) => {
+                switch (add_gcroot("/nix/store/" ++ inpt, flake_input_cache_path ++ inpt)) {
+                | Ok() => ()
+                | err => Printf.eprintf("Failed creating flake-input gcroot: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
+                };
+              });
+            print_cur_cache(profile_rc);
+          }
+        | err => {
+            Printf.eprintf("Failed creating gcroot: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
+            exit(1);
+          }
+        };
+      }
+    | err => {
+        Printf.eprintf("Failed evaluating flake: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
+        exit(1);
+      }
+    };
+  };
+
+let preflight = (layout_directory) => {
+  switch (Versions.preflight_versions(), Sys_unix.is_directory(layout_directory)) {
+  | (Ok(_), `Yes) => Ok()
+  | (Ok(_), _) => {
+      Unix.mkdir_p(layout_directory);
+      Ok()
+    }
+  | (err, _) => err
+  }
+}

tests/dune

@@ -0,0 +1,7 @@
+(tests
+  (names
+    flake_env_test_versions
+    flake_env_test_watches
+    flake_env_test_util)
+  (instrumentation (backend bisect_ppx))
+  (libraries lib alcotest))

tests/flake_env_test_util.re

@@ -0,0 +1,39 @@
+open Core;
+module Unix = Core_unix;
+
+open Lib.Util;
+
+let pp_exit_or_signal = (pp_fmt) => (e) => Fmt.pf(pp_fmt, "%s", Unix.Exit_or_signal.to_string_hum(e));
+let exit_or_signal_eq = (a, b) => Unix.Exit_or_signal.compare(a, b) == 0;
+let testable_exit_or_signal = Alcotest.testable(pp_exit_or_signal, exit_or_signal_eq);
+
+let test_run_process_success = () => 
+  Alcotest.(check(Alcotest.pair(testable_exit_or_signal, string)))(
+  "Returns expected",
+  (Ok(), ""),
+  run_process("true", []));
+
+let test_run_process_failure = () => 
+  Alcotest.(check(Alcotest.pair(testable_exit_or_signal, string)))(
+  "Returns expected",
+  (Error(`Exit_non_zero(1)), ""),
+  run_process("false", []));
+
+let test_run_process_stdout = () => 
+  Alcotest.(check(Alcotest.pair(testable_exit_or_signal, string)))(
+  "Returns expected",
+  (Ok(), "echoed\n"),
+  run_process("echo", ["echoed"]));
+
+let () =
+  Alcotest.(
+  run(
+    "Watches",
+    [("run_process",
+      [
+      test_case("Capture's Stdout", `Quick, test_run_process_stdout),
+      test_case("Success", `Quick, test_run_process_success),
+      test_case("Failure", `Quick, test_run_process_failure),
+    ]),
+  ]),
+);

tests/flake_env_test_versions.re

@@ -0,0 +1,118 @@
+open Lib;
+
+let test_compare_equal = () => {
+  let a = Versions.init(1,0,0);
+  Alcotest.(check(int))("equal", 0, Versions.compare(a, a))
+};
+
+let test_compare_first_major_greater = () => {
+  let a = Versions.init(2,0,0);
+  let b = Versions.init(1, 0, 0);
+  Alcotest.(check(int))("First major greater", 1, Versions.compare(a, b))
+};
+
+let test_compare_first_minor_greater = () => {
+  let a = Versions.init(1,1,0);
+  let b = Versions.init(1, 0, 0);
+  Alcotest.(check(int))("First minor greater", 1, Versions.compare(a, b))
+};
+
+let test_compare_first_point_greater = () => {
+  let a = Versions.init(1, 0, 1);
+  let b = Versions.init(1,0,0);
+  Alcotest.(check(int))("First point greater", 1, Versions.compare(a, b))
+};
+
+let test_compare_second_major_greater = () => {
+  let a = Versions.init(1,0,0);
+  let b = Versions.init(2, 0, 0);
+  Alcotest.(check(int))("Second major greater", -1, Versions.compare(a, b))
+};
+
+let test_compare_second_minor_greater = () => {
+  let a = Versions.init(1,0,0);
+  let b = Versions.init(1, 1, 0);
+  Alcotest.(check(int))("Second minor greater", -1, Versions.compare(a, b))
+};
+
+let test_compare_second_point_greater = () => {
+  let a = Versions.init(1,0,0);
+  let b = Versions.init(1, 0, 1);
+  Alcotest.(check(int))("Second point greater", -1, Versions.compare(a, b))
+};
+
+let test_ine_cur_newer = () => {
+  let a = Ok(Versions.init(2,0,0));
+  let b = Versions.init(1, 0, 0);
+  let ine = Versions.is_new_enough(a, b);
+  Alcotest.(check(bool))("Curr newer", true, ine |> Result.get_ok)
+};
+
+let test_ine_cur_older = () => {
+  let a = Ok(Versions.init(1,0,0));
+  let b = Versions.init(2, 0, 0);
+  let ine = Versions.is_new_enough(a, b);
+  Alcotest.(check(bool))("Curr older", false, ine |> Result.get_ok)
+};
+
+let test_ine_cur_equal = () => {
+  let a = Versions.init(1,0,0);
+  let ine = Versions.is_new_enough(Ok(a), a);
+  Alcotest.(check(bool))("Curr equal", true, ine |> Result.get_ok)
+};
+
+// TODO: figure out typing of `Alcotest.check` here.
+// I think we just add a `pprint` and `equal` function, but that is verbose
+// let test_ine_error = () => {
+//   let a = Error("foobarbaz");
+//   let ine = Versions.is_new_enough(a, Versions.init(1, 0, 0));
+//   Alcotest.(check())("Error bubbled", Error("foobarbaz"), ine)
+// };
+
+let test_in_direnv_true = () => {
+  Core_unix.putenv(~key="direnv", ~data="direnv");
+  Alcotest.(check(bool))("In direnv", true, Versions.in_direnv())
+};
+
+let test_in_direnv_false = () => {
+  Core_unix.unsetenv("direnv");
+  Alcotest.(check(bool))("Not in direnv", false, Versions.in_direnv())
+};
+
+// TODO: Test:
+// * extract_version_number: impure, don't know how to get a concrete version number to test against
+// * preflight_versions? impure, but m
+let () =
+  Alcotest.(
+  run(
+    "Versions",
+    [
+    (
+      "compare",
+      [
+      test_case("Versions Equal", `Quick, test_compare_equal),
+      test_case("First Major Greater", `Quick, test_compare_first_major_greater),
+      test_case("First Minor Greater", `Quick, test_compare_first_minor_greater),
+      test_case("First Point Greater", `Quick, test_compare_first_point_greater),
+      test_case("Second Major Greater", `Quick, test_compare_second_major_greater),
+      test_case("Second Minor Greater", `Quick, test_compare_second_minor_greater),
+      test_case("Second Point Greater", `Quick, test_compare_second_point_greater),
+    ],
+    ),
+    (
+      "is_new_enough",
+      [
+      test_case("Curr Newer", `Quick, test_ine_cur_newer),
+      test_case("Curr Older", `Quick, test_ine_cur_older),
+      test_case("Curr Equal", `Quick, test_ine_cur_equal),
+    ]
+    ),
+    (
+      "in_direnv",
+      [
+      test_case("true", `Quick, test_in_direnv_true),
+      test_case("false", `Quick, test_in_direnv_false),
+    ],
+    )
+  ])
+  );

tests/flake_env_test_watches.re

@@ -0,0 +1,41 @@
+open Lib.Watches;
+
+let test_get_path_removes_prefix = () => {
+  let input = `Assoc([
+    ("path", `String("aaaaaaaaaaabbbbb"))
+  ]);
+  Alcotest.(check(string))("Prefix removed", "bbbbb", get_path(input))
+};
+
+let test_get_paths_from_doc = () => {
+  let input = `Assoc([
+    ("path", `String("aaaaaaaaaaabbbbb")),
+    ("inputs", `Assoc([
+    ("foo", `Assoc([
+      ("path", `String("aaaaaaaaaaaccccc")),
+      ("inputs", `Assoc([
+      ("bar", `Assoc([
+        ("path", `String("aaaaaaaaaaaddddd")),
+        ("inputs", `Assoc([]))
+      ]))
+    ]))
+    ]))
+  ]))
+  ]);
+  Alcotest.(check(list(string)))("Gathers all inputs", ["bbbbb", "ccccc", "ddddd"], get_paths_from_doc(input, []))
+};
+
+let () =
+  Alcotest.(
+  run(
+    "Watches",
+    [("get_path",
+      [
+      test_case("Removes prefix", `Quick, test_get_path_removes_prefix),
+    ]),
+     ("get_paths_from_doc",
+      [
+       test_case("Collects all paths", `Quick, test_get_paths_from_doc),
+     ])
+  ]),
+);