fix: keep PR walkthrough links canonical (#3438)

2026-09-06 15:14:28 +01:00
parent 7cb5d8c0b3
commit 039142db80
22 changed files with 1793 additions and 106 deletions
@@ -0,0 +1,263 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
+	return f(req)
+}
+
+func githubJSONResponse(req *http.Request, status int, payload any) *http.Response {
+	body, err := json.Marshal(payload)
+	if err != nil {
+		panic(err)
+	}
+	return &http.Response{
+		StatusCode: status,
+		Header:     make(http.Header),
+		Body:       io.NopCloser(strings.NewReader(string(body))),
+		Request:    req,
+	}
+}
+
+func TestUpsertDescriptionSectionPreservesBodyChangedBeforePatch(t *testing.T) {
+	// @covers AC-UI-PR-WALKTHROUGH-001.10
+	originalBody := "Contributor content"
+	newerBody := originalBody + "\n\nPreview bot content"
+	currentBody := originalBody
+	getCount := 0
+	var patchedBody string
+
+	previousTransport := http.DefaultTransport
+	http.DefaultTransport = roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		switch req.Method {
+		case http.MethodGet:
+			getCount++
+			if getCount == 2 {
+				currentBody = newerBody
+			}
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		case http.MethodPatch:
+			var payload struct {
+				Body string `json:"body"`
+			}
+			if err := json.NewDecoder(req.Body).Decode(&payload); err != nil {
+				return nil, err
+			}
+			patchedBody = payload.Body
+			currentBody = patchedBody
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		default:
+			return githubJSONResponse(req, http.StatusNotFound, map[string]string{}), nil
+		}
+	})
+	t.Cleanup(func() { http.DefaultTransport = previousTransport })
+
+	err := upsertDescriptionSection(
+		context.Background(),
+		"token",
+		"owner/repo",
+		1,
+		"### Preview\nURL: https://example.com",
+	)
+	if err != nil {
+		t.Fatalf("upsertDescriptionSection() error = %v", err)
+	}
+	if !strings.Contains(patchedBody, "Preview bot content") {
+		t.Fatalf("patched body lost newer content: %q", patchedBody)
+	}
+	if !strings.Contains(patchedBody, sectionStart) {
+		t.Fatalf("patched body lost preview section: %q", patchedBody)
+	}
+	if getCount < 4 {
+		t.Fatalf("expected fresh snapshot and readback, got %d GET requests", getCount)
+	}
+}
+
+func TestUpsertDescriptionSectionRetriesAfterReadbackLosesUpdate(t *testing.T) {
+	// @covers AC-UI-PR-WALKTHROUGH-001.10
+	currentBody := "Contributor content"
+	patchCount := 0
+	getCount := 0
+
+	previousTransport := http.DefaultTransport
+	http.DefaultTransport = roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		switch req.Method {
+		case http.MethodGet:
+			getCount++
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		case http.MethodPatch:
+			patchCount++
+			var payload struct {
+				Body string `json:"body"`
+			}
+			if err := json.NewDecoder(req.Body).Decode(&payload); err != nil {
+				return nil, err
+			}
+			if patchCount == 1 {
+				currentBody = "External writer won"
+			} else {
+				currentBody = payload.Body
+			}
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		default:
+			return githubJSONResponse(req, http.StatusNotFound, map[string]string{}), nil
+		}
+	})
+	t.Cleanup(func() { http.DefaultTransport = previousTransport })
+
+	err := upsertDescriptionSection(
+		context.Background(),
+		"token",
+		"owner/repo",
+		1,
+		"### Preview\nURL: https://example.com",
+	)
+	if err != nil {
+		t.Fatalf("upsertDescriptionSection() error = %v", err)
+	}
+	if patchCount != 2 {
+		t.Fatalf("expected a retry after readback loss, got %d PATCH requests", patchCount)
+	}
+	if !strings.Contains(currentBody, sectionStart) {
+		t.Fatalf("final body lost preview section: %q", currentBody)
+	}
+	if !strings.Contains(currentBody, "External writer won") {
+		t.Fatalf("final body lost external content: %q", currentBody)
+	}
+	if getCount < 6 {
+		t.Fatalf("expected readback and retry reads, got %d GET requests", getCount)
+	}
+}
+
+func TestUpsertDescriptionSectionFailsAfterRepeatedBodyChanges(t *testing.T) {
+	// @covers AC-UI-PR-WALKTHROUGH-001.10
+	getCount := 0
+	patchCount := 0
+
+	previousTransport := http.DefaultTransport
+	http.DefaultTransport = roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		switch req.Method {
+		case http.MethodGet:
+			getCount++
+			return githubJSONResponse(req, http.StatusOK, map[string]string{
+				"body": "Body version " + string(rune('0'+getCount)),
+			}), nil
+		case http.MethodPatch:
+			patchCount++
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": "ignored"}), nil
+		default:
+			return githubJSONResponse(req, http.StatusNotFound, map[string]string{}), nil
+		}
+	})
+	t.Cleanup(func() { http.DefaultTransport = previousTransport })
+
+	err := upsertDescriptionSection(
+		context.Background(),
+		"token",
+		"owner/repo",
+		1,
+		"### Preview\nURL: https://example.com",
+	)
+	if err == nil {
+		t.Fatal("upsertDescriptionSection() error = nil, want bounded convergence failure")
+	}
+	if !strings.Contains(err.Error(), "did not converge") {
+		t.Fatalf("error = %v, want convergence failure", err)
+	}
+	if patchCount != 0 {
+		t.Fatalf("expected no stale PATCH requests, got %d", patchCount)
+	}
+}
+
+func TestRemoveDescriptionSectionPreservesOtherOwnedContent(t *testing.T) {
+	// @covers AC-UI-PR-WALKTHROUGH-001.10
+	walkthrough := "<!-- kandev-pr-walkthrough-start -->\nwalkthrough\n<!-- kandev-pr-walkthrough-end -->"
+	currentBody := walkthrough + "\n\n" + sectionStart + "\npreview\n" + sectionEnd
+	patchCount := 0
+
+	previousTransport := http.DefaultTransport
+	http.DefaultTransport = roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		switch req.Method {
+		case http.MethodGet:
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		case http.MethodPatch:
+			patchCount++
+			var payload struct {
+				Body string `json:"body"`
+			}
+			if err := json.NewDecoder(req.Body).Decode(&payload); err != nil {
+				return nil, err
+			}
+			currentBody = payload.Body
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		default:
+			return githubJSONResponse(req, http.StatusNotFound, map[string]string{}), nil
+		}
+	})
+	t.Cleanup(func() { http.DefaultTransport = previousTransport })
+
+	if err := removeDescriptionSection(context.Background(), "token", "owner/repo", 1); err != nil {
+		t.Fatalf("removeDescriptionSection() error = %v", err)
+	}
+	if patchCount != 1 {
+		t.Fatalf("expected one PATCH request, got %d", patchCount)
+	}
+	if !strings.Contains(currentBody, walkthrough) {
+		t.Fatalf("removeDescriptionSection() lost walkthrough content: %q", currentBody)
+	}
+	if strings.Contains(currentBody, sectionStart) || strings.Contains(currentBody, sectionEnd) {
+		t.Fatalf("removeDescriptionSection() kept preview markers: %q", currentBody)
+	}
+}
+
+func TestRemoveDescriptionSectionWithoutMarkerDoesNotPatch(t *testing.T) {
+	// @covers AC-UI-PR-WALKTHROUGH-001.10
+	patchCount := 0
+	previousTransport := http.DefaultTransport
+	http.DefaultTransport = roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		if req.Method == http.MethodPatch {
+			patchCount++
+		}
+		return githubJSONResponse(req, http.StatusOK, map[string]string{"body": "Contributor content"}), nil
+	})
+	t.Cleanup(func() { http.DefaultTransport = previousTransport })
+
+	if err := removeDescriptionSection(context.Background(), "token", "owner/repo", 1); err != nil {
+		t.Fatalf("removeDescriptionSection() error = %v", err)
+	}
+	if patchCount != 0 {
+		t.Fatalf("expected no PATCH request without a marker, got %d", patchCount)
+	}
+}
+
+func TestRemoveDescriptionSectionWithOrphanEndMarkerDoesNotPatch(t *testing.T) {
+	currentBody := "Contributor content\n\n" + sectionEnd
+	patchCount := 0
+	previousTransport := http.DefaultTransport
+	http.DefaultTransport = roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		switch req.Method {
+		case http.MethodGet:
+			return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+		case http.MethodPatch:
+			patchCount++
+		}
+		return githubJSONResponse(req, http.StatusOK, map[string]string{"body": currentBody}), nil
+	})
+	t.Cleanup(func() { http.DefaultTransport = previousTransport })
+
+	if err := removeDescriptionSection(context.Background(), "token", "owner/repo", 1); err != nil {
+		t.Fatalf("removeDescriptionSection() error = %v", err)
+	}
+	if patchCount != 0 {
+		t.Fatalf("expected no PATCH request for an orphan end marker, got %d", patchCount)
+	}
+}