fix(github): add DismissReview Event comment; use t.Fatalf for routing assertions

- Add comment in DismissReview explaining why the Event field is required
  by the GitHub API even though DISMISS is the only valid value (#18652).
- Change t.Errorf to t.Fatalf for method/path routing assertions in test
  handlers so failures are immediately fatal instead of silently
  continuing handler execution (#18653).

gitea/position.go

@@ -11,7 +11,6 @@ import (
 type PositionMap struct {
 	// files maps filename → (position → new-file line number).
 	// Deletion lines are mapped to -1 (no new-file line).
-	// Hunk-header lines are mapped to 0 (no new-file line).
 	files map[string]map[int]int
 	// maxPositions caches the highest position number per file,
 	// tracked during construction to avoid O(n) scans at translate time.
@@ -20,8 +19,8 @@ type PositionMap struct {
 
 // Translate converts a GitHub diff-position to a new-file line number for a given file.
 // Returns an error if the file is not in the diff or the position is out of range.
-// If the position targets a deletion or hunk-header line, it maps to the nearest
-// context/addition line below; if no such line exists, returns an error.
+// If the position targets a deletion line, it maps to the nearest non-deletion line below;
+// if no such line exists, returns an error.
 func (pm *PositionMap) Translate(file string, position int) (int, error) {
 	if pm == nil || pm.files == nil {
 		return 0, fmt.Errorf("empty position map")
@@ -42,18 +41,14 @@ func (pm *PositionMap) Translate(file string, position int) (int, error) {
 	}
 
 	// lineNum == -1 means this position is a deletion line.
-	// lineNum == 0 means this position is a hunk-header line.
-	// Both map to the nearest context/addition line below.
-	if lineNum <= 0 {
+	// Map to the nearest non-deletion line below.
+	if lineNum == -1 {
 		maxPos := pm.maxPosition(file)
 		for p := position + 1; p <= maxPos; p++ {
 			if ln, exists := fileMap[p]; exists && ln > 0 {
 				return ln, nil
 			}
 		}
-		if lineNum == 0 {
-			return 0, fmt.Errorf("position %d targets a hunk-header line with no subsequent new-file line in %q", position, file)
-		}
 		return 0, fmt.Errorf("position %d targets a deletion line with no subsequent new-file line in %q", position, file)
 	}
 
@@ -75,7 +70,6 @@ func (pm *PositionMap) maxPosition(file string) int {
 //   - A new @@ hunk within the same file continues incrementing (does not reset)
 //   - Position maps to the new file line number for additions and context lines
 //   - Deletion lines have a position but no new-file line number (stored as -1)
-//   - Hunk-header lines have a position but no new-file line number (stored as 0)
 func BuildPositionToLineMap(diff string) *PositionMap {
 	pm := &PositionMap{
 		files:        make(map[string]map[int]int),
@@ -132,7 +126,6 @@ func BuildPositionToLineMap(diff string) *PositionMap {
 		// Parse hunk headers
 		if strings.HasPrefix(line, "@@") && currentFile != "" {
 			position++
-			pm.files[currentFile][position] = 0 // sentinel: hunk-header has no new-file line
 			pm.maxPositions[currentFile] = position
 			newLine = parseHunkStart(line)
 			continue

gitea/position_test.go

@@ -272,112 +272,3 @@ diff --git a/b.go b/b.go
 		t.Errorf("Translate(b.go, 3) = %d, want 2", got)
 	}
 }
-
-func TestTranslate_HunkHeaderPosition_SingleHunk(t *testing.T) {
-	// Position 1 is the @@ hunk-header line.
-	// It should resolve to the first context/addition line below (new line 16).
-	diff := `diff --git a/file.go b/file.go
-index abc..def 100644
---- a/file.go
-+++ b/file.go
-@@ -16,4 +16,5 @@ func example() {
- context line
--deleted line
-+added line
- context after
-`
-	pm := BuildPositionToLineMap(diff)
-
-	got, err := pm.Translate("file.go", 1)
-	if err != nil {
-		t.Fatalf("Translate(file.go, 1): unexpected error: %v", err)
-	}
-	if got != 16 {
-		t.Errorf("Translate(file.go, 1) = %d, want 16 (first context/addition line in hunk)", got)
-	}
-}
-
-func TestTranslate_HunkHeaderPosition_MultiHunk(t *testing.T) {
-	// First hunk: @@ is pos 1, then " line1" (pos 2), "-old" (pos 3), "+new" (pos 4)
-	// Second hunk: @@ is pos 5, then " func foo() {" (pos 6), "+// added" (pos 7), etc.
-	// Translating position 5 (second @@) should resolve to new line 10.
-	diff := `diff --git a/file.go b/file.go
---- a/file.go
-+++ b/file.go
-@@ -1,3 +1,3 @@ package main
- line1
--old
-+new
-@@ -10,3 +10,4 @@ func foo() {
- func foo() {
-+	// added
- 	return
- }
-`
-	pm := BuildPositionToLineMap(diff)
-
-	// Position 5 is the second @@ hunk-header — should resolve to new line 10
-	got, err := pm.Translate("file.go", 5)
-	if err != nil {
-		t.Fatalf("Translate(file.go, 5): unexpected error: %v", err)
-	}
-	if got != 10 {
-		t.Errorf("Translate(file.go, 5) = %d, want 10 (first context/addition line in second hunk)", got)
-	}
-
-	// Also verify first hunk header at position 1 resolves to new line 1
-	got, err = pm.Translate("file.go", 1)
-	if err != nil {
-		t.Fatalf("Translate(file.go, 1): unexpected error: %v", err)
-	}
-	if got != 1 {
-		t.Errorf("Translate(file.go, 1) = %d, want 1 (first context/addition line in first hunk)", got)
-	}
-}
-
-func TestTranslate_HunkHeaderPosition_NewFile(t *testing.T) {
-	// New file: @@ -0,0 +1,3 @@ is position 1.
-	// Should resolve to new line 1 (the first addition).
-	diff := `diff --git a/new.go b/new.go
-new file mode 100644
---- /dev/null
-+++ b/new.go
-@@ -0,0 +1,3 @@
-+package main
-+
-+func init() {}
-`
-	pm := BuildPositionToLineMap(diff)
-
-	got, err := pm.Translate("new.go", 1)
-	if err != nil {
-		t.Fatalf("Translate(new.go, 1): unexpected error: %v", err)
-	}
-	if got != 1 {
-		t.Errorf("Translate(new.go, 1) = %d, want 1 (first addition line)", got)
-	}
-}
-
-func TestTranslate_HunkHeaderAtEnd(t *testing.T) {
-	// A hunk-header at the last position with no subsequent new-file line should error.
-	// This is the hunk-header equivalent of TestBuildPositionToLineMap_DeletionAtEnd.
-	diff := `diff --git a/file.go b/file.go
---- a/file.go
-+++ b/file.go
-@@ -1,2 +1,2 @@ package main
- line1
--old
-+new
-@@ -10,2 +10,1 @@ func foo() {
--removed
-`
-	pm := BuildPositionToLineMap(diff)
-
-	// Position 5 is the second @@ hunk-header; the only line after it (pos 6) is a
-	// deletion (lineNum == -1), so there's no positive new-file line to resolve to.
-	// The hunk-header lookup should fail.
-	_, err := pm.Translate("file.go", 5)
-	if err == nil {
-		t.Error("expected error for hunk-header at end with no subsequent new-file line")
-	}
-}