feat: add pr commits/branches/check-merge shortcuts with tests

Add three new shortcuts to the pr module:
- commits: list commits in a pull request (v1 API)
- branches: list branches for PR creation
- check-merge: check if two branches can be merged

Each shortcut includes unit tests covering both success and HTTP error paths.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

shortcuts/pr/pr.go

@@ -364,6 +364,72 @@ func Shortcuts() []*common.Shortcut {
 				return ctx.Output(env)
 			},
 		},
+		{
+			Name:        "commits",
+			Description: "List commits in a pull request",
+			Flags: []common.Flag{
+				{Name: "id", Short: "i", Usage: "PR number", Required: true},
+			},
+			Run: func(ctx *common.RuntimeContext) error {
+				if err := ctx.ResolveOwnerRepo(); err != nil {
+					return err
+				}
+				id, err := ctx.RequireArg("id")
+				if err != nil {
+					return err
+				}
+				env, err := ctx.CallAPI("GET", prV1Path(ctx, id)+"/commits", nil)
+				if err != nil {
+					return err
+				}
+				return ctx.Output(env)
+			},
+		},
+		{
+			Name:        "branches",
+			Description: "List branches for pull request creation",
+			Flags:       []common.Flag{},
+			Run: func(ctx *common.RuntimeContext) error {
+				if err := ctx.ResolveOwnerRepo(); err != nil {
+					return err
+				}
+				env, err := ctx.CallAPI("GET", ctx.RepoPath()+"/pulls/get_branches", nil)
+				if err != nil {
+					return err
+				}
+				return ctx.Output(env)
+			},
+		},
+		{
+			Name:        "check-merge",
+			Description: "Check if two branches can be merged",
+			Flags: []common.Flag{
+				{Name: "head", Usage: "Source branch", Required: true},
+				{Name: "base", Usage: "Target branch", Required: true},
+			},
+			Run: func(ctx *common.RuntimeContext) error {
+				if err := ctx.ResolveOwnerRepo(); err != nil {
+					return err
+				}
+				head, err := ctx.RequireArg("head")
+				if err != nil {
+					return err
+				}
+				base, err := ctx.RequireArg("base")
+				if err != nil {
+					return err
+				}
+				payload := map[string]interface{}{
+					"head": head,
+					"base": base,
+				}
+				env, err := ctx.CallAPI("POST", ctx.RepoPath()+"/pulls/check_can_merge", payload)
+				if err != nil {
+					return err
+				}
+				return ctx.Output(env)
+			},
+		},
 	}
 }
 

shortcuts/pr/pr_test.go

@@ -426,6 +426,120 @@ func TestPRDiffHTTPError(t *testing.T) {
 	}
 }
 
+// --- commits ---
+
+func TestPRCommits(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "GET" {
+			t.Fatalf("expected GET, got %s", r.Method)
+		}
+		if r.URL.Path != "/v1/owner/repo/pulls/42/commits.json" {
+			t.Fatalf("unexpected path: %s", r.URL.Path)
+		}
+		writeJSON(t, w, []interface{}{
+			map[string]interface{}{"sha": "abc1234", "message": "fix: bug"},
+		})
+	}))
+	defer server.Close()
+
+	err := runPRShortcut(t, server, "commits", map[string]string{"id": "42"})
+	if err != nil {
+		t.Fatalf("commits failed: %v", err)
+	}
+}
+
+func TestPRCommitsHTTPError(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("server error"))
+	}))
+	defer server.Close()
+
+	err := runPRShortcut(t, server, "commits", map[string]string{"id": "42"})
+	if err == nil {
+		t.Fatal("expected error for HTTP 500")
+	}
+}
+
+// --- branches ---
+
+func TestPRBranches(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "GET" {
+			t.Fatalf("expected GET, got %s", r.Method)
+		}
+		if r.URL.Path != "/owner/repo/pulls/get_branches.json" {
+			t.Fatalf("unexpected path: %s", r.URL.Path)
+		}
+		writeJSON(t, w, []interface{}{
+			map[string]interface{}{"name": "master"},
+			map[string]interface{}{"name": "develop"},
+		})
+	}))
+	defer server.Close()
+
+	err := runPRShortcut(t, server, "branches", map[string]string{})
+	if err != nil {
+		t.Fatalf("branches failed: %v", err)
+	}
+}
+
+func TestPRBranchesHTTPError(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("server error"))
+	}))
+	defer server.Close()
+
+	err := runPRShortcut(t, server, "branches", map[string]string{})
+	if err == nil {
+		t.Fatal("expected error for HTTP 500")
+	}
+}
+
+// --- check-merge ---
+
+func TestPRCheckMerge(t *testing.T) {
+	var payload map[string]interface{}
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("expected POST, got %s", r.Method)
+		}
+		if r.URL.Path != "/owner/repo/pulls/check_can_merge.json" {
+			t.Fatalf("unexpected path: %s", r.URL.Path)
+		}
+		payload = decodeJSON(t, r)
+		writeJSON(t, w, map[string]interface{}{"can_merge": true})
+	}))
+	defer server.Close()
+
+	err := runPRShortcut(t, server, "check-merge", map[string]string{
+		"head": "feature/x",
+		"base": "master",
+	})
+	if err != nil {
+		t.Fatalf("check-merge failed: %v", err)
+	}
+	assertEqual(t, payload["head"], "feature/x")
+	assertEqual(t, payload["base"], "master")
+}
+
+func TestPRCheckMergeHTTPError(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("server error"))
+	}))
+	defer server.Close()
+
+	err := runPRShortcut(t, server, "check-merge", map[string]string{
+		"head": "feature/x",
+		"base": "master",
+	})
+	if err == nil {
+		t.Fatal("expected error for HTTP 500")
+	}
+}
+
 func runPRShortcut(t *testing.T, server *httptest.Server, name string, args map[string]string) error {
 	t.Helper()
 	shortcut := findPRShortcut(t, name)