tests: add unit tests for parsing of GH links

Check for different possible url schemes and other variations.

Author: yasunariw

test/dune

@@ -1,5 +1,5 @@
-(executable
- (name test)
+(executables
+ (names test github_link_test)
  (libraries lib base base.caml devkit devkit.core extlib lwt.unix stdio
    yojson)
  (preprocess
@@ -21,3 +21,8 @@
  (alias runtest)
  (action
   (diff slack_payloads.expected slack_payloads.out)))
+
+(rule
+ (alias runtest)
+ (action
+   (run ./github_link_test.exe)))

test/github_link_test.ml

@@ -0,0 +1,50 @@
+open Base
+open Printf
+open Lib
+open Github
+open Github_t
+
+let mk_repo ?(scheme = "https") prefix prefix_api : repository =
+  {
+    name = "monorepo";
+    full_name = "ahrefs/monorepo";
+    url = sprintf "%s://%s/ahrefs/monorepo" scheme prefix;
+    commits_url = sprintf "%s://%s/repos/ahrefs/monorepo/commits{/sha}" scheme prefix_api;
+    contents_url = sprintf "%s://%s/repos/ahrefs/monorepo/contents/{+path}" scheme prefix_api;
+  }
+
+let enterprise_repo1 = mk_repo "example.org" "example.org/api/v3"
+
+let enterprise_repo2 = mk_repo "example.org/path/to/git" "example.org/path/to/git/api/v3"
+
+let enterprise_repo_insecure = mk_repo ~scheme:"http" "example.org" "example.org/api/v3"
+
+let github_repo = mk_repo "github.com" "api.github.com"
+
+let commit_cases prefix repo =
+  [
+    sprintf "https://%s/ahrefs/monorepo/commit/69c42640" prefix, Some (Commit (repo, "69c42640"));
+    sprintf "https://%s/ahrefs/monorepo/commit/69c42640/" prefix, Some (Commit (repo, "69c42640"));
+    sprintf "https://%s/ahrefs/monorepo/commit/69c42640?arg1=123" prefix, Some (Commit (repo, "69c42640"));
+    sprintf "https://%s/ahrefs/monorepo/commit/" prefix, None;
+    sprintf "https://%s/ahrefs/monorepo/commit" prefix, None;
+  ]
+
+let other_cases =
+  [
+    "http://github.com/ahrefs/monorepo/commit/69c42640", Some (Commit (github_repo, "69c42640"));
+    "http://example.org/ahrefs/monorepo/commit/69c42640", Some (Commit (enterprise_repo_insecure, "69c42640"));
+    "abc", None;
+  ]
+
+let cases =
+  List.concat
+    [
+      commit_cases "github.com" github_repo;
+      commit_cases "www.github.com" github_repo;
+      commit_cases "example.org" enterprise_repo1;
+      commit_cases "example.org/path/to/git" enterprise_repo2;
+      other_cases;
+    ]
+
+let () = List.iter cases ~f:(fun (input, expected) -> assert (Poly.equal (gh_link_of_string input) expected))