Add function to get commit diff/patch (#589)

- Adds function the gets a commit's diff or patch.
- Ref: https://github.com/go-gitea/gitea/pull/17095

Reviewed-on: https://gitea.com/gitea/go-sdk/pulls/589
Reviewed-by: John Olheiser <john.olheiser@gmail.com>
Reviewed-by: 6543 <6543@obermui.de>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-committed-by: Gusted <williamzijl7@hotmail.com>

gitea/repo_commit.go

@@ -113,3 +113,29 @@ func (c *Client) ListRepoCommits(user, repo string, opt ListCommitOptions) ([]*C
 	resp, err := c.getParsedResponse("GET", link.String(), nil, nil, &commits)
 	return commits, resp, err
 }
+
+// GetCommitDiff returns the commit's raw diff.
+func (c *Client) GetCommitDiff(user, repo, commitID string) ([]byte, *Response, error) {
+	if err := c.checkServerVersionGreaterThanOrEqual(version1_16_0); err != nil {
+		return nil, nil, err
+	}
+
+	if err := escapeValidatePathSegments(&user, &repo); err != nil {
+		return nil, nil, err
+	}
+
+	return c.getResponse("GET", fmt.Sprintf("/repos/%s/%s/git/commits/%s.%s", user, repo, commitID, pullRequestDiffTypeDiff), nil, nil)
+}
+
+// GetCommitPatch returns the commit's raw patch.
+func (c *Client) GetCommitPatch(user, repo, commitID string) ([]byte, *Response, error) {
+	if err := c.checkServerVersionGreaterThanOrEqual(version1_16_0); err != nil {
+		return nil, nil, err
+	}
+
+	if err := escapeValidatePathSegments(&user, &repo); err != nil {
+		return nil, nil, err
+	}
+
+	return c.getResponse("GET", fmt.Sprintf("/repos/%s/%s/git/commits/%s.%s", user, repo, commitID, pullRequestDiffTypePatch), nil, nil)
+}

gitea/repo_commit_test.go

@@ -5,6 +5,7 @@
 package gitea
 
 import (
+	"encoding/base64"
 	"log"
 	"testing"
 
@@ -25,3 +26,35 @@ func TestListRepoCommits(t *testing.T) {
 	assert.EqualValues(t, "gpg.error.not_signed_commit", l[0].RepoCommit.Verification.Reason)
 	assert.EqualValues(t, 100, l[0].Stats.Additions)
 }
+
+func TestGetCommitDiffOrPatch(t *testing.T) {
+	log.Println("== TestGetCommitDiffOrPatch ==")
+	c := newTestClient()
+
+	repo, err := createTestRepo(t, "TestGetCommitDiffOrPatch", c)
+	assert.NoError(t, err)
+
+	// Add a new simple small commit to the repository.
+	fileResponse, _, err := c.CreateFile(repo.Owner.UserName, repo.Name, "NOT_A_LICENSE", CreateFileOptions{
+		Content: base64.StdEncoding.EncodeToString([]byte("But is it?\n")),
+		FileOptions: FileOptions{
+			Message: "Ensure people know it's not a license!",
+			Committer: Identity{
+				Name:  "Sup3rCookie",
+				Email: "Sup3rCookie@example.com",
+			},
+		},
+	})
+	assert.NoError(t, err)
+
+	// Test the diff output.
+	diffOutput, _, err := c.GetCommitDiff(repo.Owner.UserName, repo.Name, fileResponse.Commit.SHA)
+	assert.NoError(t, err)
+	assert.EqualValues(t, "diff --git a/NOT_A_LICENSE b/NOT_A_LICENSE\nnew file mode 100644\nindex 0000000..f27a20a\n--- /dev/null\n+++ b/NOT_A_LICENSE\n@@ -0,0 +1 @@\n+But is it?\n", string(diffOutput))
+
+	// Test the patch output.
+	patchOutput, _, err := c.GetCommitPatch(repo.Owner.UserName, repo.Name, fileResponse.Commit.SHA)
+	assert.NoError(t, err)
+	// Use contains, because we cannot include the first part, because of dates + non-static CommitID..
+	assert.Contains(t, string(patchOutput), "Subject: [PATCH] Ensure people know it's not a license!\n\n---\n NOT_A_LICENSE | 1 +\n 1 file changed, 1 insertion(+)\n create mode 100644 NOT_A_LICENSE\n\ndiff --git a/NOT_A_LICENSE b/NOT_A_LICENSE\nnew file mode 100644\nindex 0000000..f27a20a\n--- /dev/null\n+++ b/NOT_A_LICENSE\n@@ -0,0 +1 @@\n+But is it?\n")
+}