DocumentLoader for GitHub (#5408)

# Creates GitHubLoader (#5257)

GitHubLoader is a DocumentLoader that loads issues and PRs from GitHub.

Fixes #5257

---------

Co-authored-by: Dev 2049 <dev.dev2049@gmail.com>

tests/unit_tests/document_loaders/test_github.py

@@ -0,0 +1,114 @@
+import pytest
+from pytest_mock import MockerFixture
+
+from langchain.docstore.document import Document
+from langchain.document_loaders.github import GitHubIssuesLoader
+
+
+def test_initialization() -> None:
+    loader = GitHubIssuesLoader(repo="repo", access_token="access_token")
+    assert loader.repo == "repo"
+    assert loader.access_token == "access_token"
+    assert loader.headers == {
+        "Accept": "application/vnd.github+json",
+        "Authorization": "Bearer access_token",
+    }
+
+
+def test_invalid_initialization() -> None:
+    # Invalid parameter
+    with pytest.raises(ValueError):
+        GitHubIssuesLoader(invalid="parameter")
+
+    # Invalid value for valid parameter
+    with pytest.raises(ValueError):
+        GitHubIssuesLoader(state="invalid_state")
+
+    # Invalid type for labels
+    with pytest.raises(ValueError):
+        GitHubIssuesLoader(labels="not_a_list")
+
+    # Invalid date format for since
+    with pytest.raises(ValueError):
+        GitHubIssuesLoader(since="not_a_date")
+
+
+def test_load(mocker: MockerFixture) -> None:
+    mocker.patch(
+        "requests.get", return_value=mocker.MagicMock(json=lambda: [], links=None)
+    )
+    loader = GitHubIssuesLoader(repo="repo", access_token="access_token")
+    documents = loader.load()
+    assert documents == []
+
+
+def test_parse_issue() -> None:
+    issue = {
+        "html_url": "https://github.com/repo/issue/1",
+        "title": "Example Issue 1",
+        "user": {"login": "username1"},
+        "created_at": "2023-01-01T00:00:00Z",
+        "comments": 1,
+        "state": "open",
+        "labels": [{"name": "bug"}],
+        "assignee": {"login": "username2"},
+        "milestone": {"title": "v1.0"},
+        "locked": "False",
+        "number": "1",
+        "body": "This is an example issue 1",
+    }
+    expected_document = Document(
+        page_content=issue["body"],  # type: ignore
+        metadata={
+            "url": issue["html_url"],
+            "title": issue["title"],
+            "creator": issue["user"]["login"],  # type: ignore
+            "created_at": issue["created_at"],
+            "comments": issue["comments"],
+            "state": issue["state"],
+            "labels": [label["name"] for label in issue["labels"]],  # type: ignore
+            "assignee": issue["assignee"]["login"],  # type: ignore
+            "milestone": issue["milestone"]["title"],  # type: ignore
+            "locked": issue["locked"],
+            "number": issue["number"],
+            "is_pull_request": False,
+        },
+    )
+    loader = GitHubIssuesLoader(repo="repo", access_token="access_token")
+    document = loader.parse_issue(issue)
+    assert document == expected_document
+
+
+def test_url() -> None:
+    # No parameters
+    loader = GitHubIssuesLoader(repo="repo", access_token="access_token")
+    assert loader.url == "https://api.github.com/repos/repo/issues?"
+
+    # parameters: state,  sort
+    loader = GitHubIssuesLoader(
+        repo="repo", access_token="access_token", state="open", sort="created"
+    )
+    assert (
+        loader.url == "https://api.github.com/repos/repo/issues?state=open&sort=created"
+    )
+
+    # parameters: milestone, state, assignee, creator, mentioned, labels, sort,
+    # direction, since
+    loader = GitHubIssuesLoader(
+        repo="repo",
+        access_token="access_token",
+        milestone="*",
+        state="closed",
+        assignee="user1",
+        creator="user2",
+        mentioned="user3",
+        labels=["bug", "ui", "@high"],
+        sort="comments",
+        direction="asc",
+        since="2023-05-26T00:00:00Z",
+    )
+    assert loader.url == (
+        "https://api.github.com/repos/repo/issues?milestone=*&state=closed"
+        "&assignee=user1&creator=user2&mentioned=user3&labels=bug,ui,@high"
+        "&sort=comments&direction=asc&since=2023-05-26T00:00:00Z"
+    )