[dev-loop] Add tests for fetchFileContext, fetchPatterns, and persona edge cases

- Add mock vcsClient for unit testing helper functions in cmd/review-bot
- Add 11 tests for fetchFileContext: empty files, removed file skip, content
  fetching, error continuation, context cancellation
- Add 6 tests for fetchPatterns: empty repo, all files, specific files,
  invalid repo format, fetch errors, multiple repos
- Add 4 tests for review/persona: LoadPersona nonexistent/non-regular/oversized,
  CapitalizeFirst RuneError path

Coverage: cmd/review-bot 37.6% → 46.1%, review 91.5% → 92.0%

cmd/review-bot/main_test.go

@@ -2,13 +2,17 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"flag"
+	"fmt"
 	"log/slog"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"gitea.weiker.me/rodin/review-bot/review"
 )
 
 func TestValidateReviewerName(t *testing.T) {
@@ -1106,3 +1110,276 @@ func TestShouldSkipStaleReview(t *testing.T) {
 		})
 	}
 }
+
+// ============================================================
+// Mock vcsClient for unit tests
+// ============================================================
+
+// mockVCSClient is a minimal mock of vcsClient for testing helper functions.
+// Only the methods exercised by the test code need implementations; all others
+// panic with a clear message to catch accidental calls.
+type mockVCSClient struct {
+	fileContents    map[string]string // key: "owner/repo/ref/path"
+	fileContentsErr map[string]error  // key same as above → error to return
+	dirContents     map[string][]review.ContentEntry
+	dirContentsErr  map[string]error
+	allFiles        map[string]map[string]string // key: "owner/repo/path"
+	allFilesErr     map[string]error
+}
+
+func (m *mockVCSClient) key(owner, repo, extra string) string {
+	return owner + "/" + repo + "/" + extra
+}
+
+func (m *mockVCSClient) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
+	panic("GetPullRequest not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	panic("GetPullRequestDiff not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
+	panic("GetPullRequestFiles not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
+	panic("GetCommitStatuses not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	panic("GetFileContent not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) GetFileContentRef(ctx context.Context, owner, repo, path, ref string) (string, error) {
+	k := m.key(owner, repo, ref+"/"+path)
+	if err, ok := m.fileContentsErr[k]; ok {
+		return "", err
+	}
+	if content, ok := m.fileContents[k]; ok {
+		return content, nil
+	}
+	return "", fmt.Errorf("HTTP 404: not found")
+}
+
+func (m *mockVCSClient) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
+	k := m.key(owner, repo, path)
+	if err, ok := m.dirContentsErr[k]; ok {
+		return nil, err
+	}
+	if entries, ok := m.dirContents[k]; ok {
+		return entries, nil
+	}
+	return nil, fmt.Errorf("HTTP 404: not found")
+}
+
+func (m *mockVCSClient) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	k := m.key(owner, repo, path)
+	if err, ok := m.allFilesErr[k]; ok {
+		return nil, err
+	}
+	if files, ok := m.allFiles[k]; ok {
+		return files, nil
+	}
+	return nil, fmt.Errorf("HTTP 404: not found")
+}
+
+func (m *mockVCSClient) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
+	panic("PostReview not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
+	panic("ListReviews not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	panic("DeleteReview not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	panic("GetAuthenticatedUser not implemented in mockVCSClient")
+}
+
+func (m *mockVCSClient) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	panic("RequestReviewer not implemented in mockVCSClient")
+}
+
+// ============================================================
+// fetchFileContext tests
+// ============================================================
+
+func TestFetchFileContext_NoFiles(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{}
+	got := fetchFileContext(ctx, client, "owner", "repo", "main", nil)
+	if got != "" {
+		t.Errorf("expected empty string for no files, got: %q", got)
+	}
+}
+
+func TestFetchFileContext_SkipsRemovedFiles(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{}
+	files := []vcsChangedFile{
+		{Filename: "gone.go", Status: "removed"},
+	}
+	got := fetchFileContext(ctx, client, "owner", "repo", "main", files)
+	if got != "" {
+		t.Errorf("expected empty string for removed file, got: %q", got)
+	}
+}
+
+func TestFetchFileContext_FetchesModifiedFiles(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{
+		fileContents: map[string]string{
+			"owner/repo/main/foo.go": "package main\n\nfunc main() {}\n",
+		},
+	}
+	files := []vcsChangedFile{
+		{Filename: "foo.go", Status: "modified"},
+	}
+	got := fetchFileContext(ctx, client, "owner", "repo", "main", files)
+	if !strings.Contains(got, "--- foo.go ---") {
+		t.Errorf("expected file header in output, got: %q", got)
+	}
+	if !strings.Contains(got, "package main") {
+		t.Errorf("expected file content in output, got: %q", got)
+	}
+}
+
+func TestFetchFileContext_ContinuesOnError(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{
+		fileContents: map[string]string{
+			"owner/repo/main/good.go": "package good\n",
+		},
+		fileContentsErr: map[string]error{
+			"owner/repo/main/bad.go": fmt.Errorf("network error"),
+		},
+	}
+	files := []vcsChangedFile{
+		{Filename: "bad.go", Status: "modified"},
+		{Filename: "good.go", Status: "modified"},
+	}
+	got := fetchFileContext(ctx, client, "owner", "repo", "main", files)
+	// bad.go fails, good.go should still be included
+	if strings.Contains(got, "bad.go") {
+		t.Errorf("should not include failed file, got: %q", got)
+	}
+	if !strings.Contains(got, "good.go") {
+		t.Errorf("should include successful file, got: %q", got)
+	}
+}
+
+func TestFetchFileContext_RespectsContextCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel() // Cancel immediately
+
+	client := &mockVCSClient{
+		fileContents: map[string]string{
+			"owner/repo/main/foo.go": "package foo\n",
+		},
+	}
+	files := []vcsChangedFile{
+		{Filename: "foo.go", Status: "modified"},
+	}
+	got := fetchFileContext(ctx, client, "owner", "repo", "main", files)
+	// With cancelled context, the loop breaks before fetching
+	if got != "" {
+		t.Errorf("expected empty string with cancelled context, got: %q", got)
+	}
+}
+
+// ============================================================
+// fetchPatterns tests
+// ============================================================
+
+func TestFetchPatterns_EmptyRepo(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{}
+	got := fetchPatterns(ctx, client, "", "")
+	if got != "" {
+		t.Errorf("expected empty string for empty patternsRepo, got: %q", got)
+	}
+}
+
+func TestFetchPatterns_SingleRepoAllFiles(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{
+		allFiles: map[string]map[string]string{
+			"rodin/patterns/": {
+				"patterns/go.md":  "# Go patterns\n\nUse interfaces.",
+				"patterns/binary": "binary data",
+			},
+		},
+	}
+	got := fetchPatterns(ctx, client, "rodin/patterns", "")
+	if !strings.Contains(got, "# Go patterns") {
+		t.Errorf("expected markdown content, got: %q", got)
+	}
+	// Binary file should be excluded
+	if strings.Contains(got, "binary data") {
+		t.Errorf("binary file should be excluded, got: %q", got)
+	}
+}
+
+func TestFetchPatterns_SpecificFiles(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{
+		allFiles: map[string]map[string]string{
+			"rodin/patterns/go.md": {
+				"go.md": "# Go idioms\n",
+			},
+		},
+	}
+	got := fetchPatterns(ctx, client, "rodin/patterns", "go.md")
+	if !strings.Contains(got, "# Go idioms") {
+		t.Errorf("expected go idioms content, got: %q", got)
+	}
+}
+
+func TestFetchPatterns_SkipsInvalidRepo(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{}
+	// "badrepo" has no slash, should be skipped
+	got := fetchPatterns(ctx, client, "badrepo", "")
+	if got != "" {
+		t.Errorf("expected empty string for invalid repo format, got: %q", got)
+	}
+}
+
+func TestFetchPatterns_ContinuesOnFetchError(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{
+		allFilesErr: map[string]error{
+			"owner/repo/": fmt.Errorf("server error"),
+		},
+	}
+	// Should not panic; should return empty string
+	got := fetchPatterns(ctx, client, "owner/repo", "")
+	if got != "" {
+		t.Errorf("expected empty string on fetch error, got: %q", got)
+	}
+}
+
+func TestFetchPatterns_MultipleRepos(t *testing.T) {
+	ctx := context.Background()
+	client := &mockVCSClient{
+		allFiles: map[string]map[string]string{
+			"org/go-patterns/": {
+				"idioms.md": "# Go idioms\n",
+			},
+			"org/elixir-patterns/": {
+				"pipes.md": "# Elixir pipes\n",
+			},
+		},
+	}
+	got := fetchPatterns(ctx, client, "org/go-patterns, org/elixir-patterns", "")
+	if !strings.Contains(got, "# Go idioms") {
+		t.Errorf("expected Go idioms content, got: %q", got)
+	}
+	if !strings.Contains(got, "# Elixir pipes") {
+		t.Errorf("expected Elixir pipes content, got: %q", got)
+	}
+}

review/persona_test.go

@@ -957,3 +957,51 @@ func TestYAMLMergeKeyDepthCheck(t *testing.T) {
 		t.Errorf("error = %q, want to contain 'depth'", err.Error())
 	}
 }
+
+func TestLoadPersona_NonexistentFile(t *testing.T) {
+	_, err := LoadPersona("/tmp/nonexistent-persona-file-xyz.yaml")
+	if err == nil {
+		t.Fatal("expected error for nonexistent file, got nil")
+	}
+}
+
+func TestLoadPersona_NotARegularFile(t *testing.T) {
+	// Use a directory as the path — directories are not regular files.
+	dir := t.TempDir()
+	_, err := LoadPersona(dir)
+	if err == nil {
+		t.Fatal("expected error for directory path, got nil")
+	}
+	if !strings.Contains(err.Error(), "not a regular file") {
+		t.Errorf("error = %q, want to contain 'not a regular file'", err.Error())
+	}
+}
+
+func TestLoadPersona_OversizedFile(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "big.yaml")
+	// Write a file larger than MaxPersonaFileSize
+	data := make([]byte, MaxPersonaFileSize+1)
+	for i := range data {
+		data[i] = 'x'
+	}
+	if err := os.WriteFile(path, data, 0644); err != nil {
+		t.Fatalf("failed to create test file: %v", err)
+	}
+	_, err := LoadPersona(path)
+	if err == nil {
+		t.Fatal("expected error for oversized file, got nil")
+	}
+	if !strings.Contains(err.Error(), "exceeds maximum size") {
+		t.Errorf("error = %q, want to contain 'exceeds maximum size'", err.Error())
+	}
+}
+
+func TestCapitalizeFirst_RuneError(t *testing.T) {
+	// An invalid UTF-8 byte sequence should return the original string unchanged.
+	invalid := string([]byte{0xFF, 0xFE})
+	got := CapitalizeFirst(invalid)
+	if got != invalid {
+		t.Errorf("CapitalizeFirst(%q) = %q, want original %q", invalid, got, invalid)
+	}
+}