Make tests independent of host state

internal/app/generation_test.go

@@ -510,9 +510,7 @@ func TestGenerateDetailedDoesNotReplaceSymbolicLinkOutput(t *testing.T) {
 		t.Fatal(err)
 	}
 	outputPath := filepath.Join(dir, "daily.md")
-	if err := os.Symlink(backing, outputPath); err != nil {
-		t.Fatal(err)
-	}
+	requireSymlink(t, backing, outputPath)
 	bundle := generationBundle(t)
 	collector := &generationCollector{bundle: &bundle}
 	executor := &generationExecutor{}

internal/app/output_test.go

@@ -46,9 +46,7 @@ func TestResolveComparisonOutputDirectory(t *testing.T) {
 func TestResolveOutputDirRejectsDanglingSymlinkComponents(t *testing.T) {
 	workingDir := t.TempDir()
 	dangling := filepath.Join(workingDir, "dangling")
-	if err := os.Symlink(filepath.Join(workingDir, "missing"), dangling); err != nil {
-		t.Fatal(err)
-	}
+	requireSymlink(t, filepath.Join(workingDir, "missing"), dangling)
 
 	for _, directory := range []string{dangling, filepath.Join(dangling, "reports")} {
 		t.Run(filepath.Base(directory), func(t *testing.T) {
@@ -63,9 +61,7 @@ func TestResolveOutputDirAllowsMissingDirectoryBelowValidSymlink(t *testing.T) {
 	workingDir := t.TempDir()
 	target := t.TempDir()
 	link := filepath.Join(workingDir, "linked")
-	if err := os.Symlink(target, link); err != nil {
-		t.Fatal(err)
-	}
+	requireSymlink(t, target, link)
 
 	directory := filepath.Join(link, "reports")
 	got, err := resolveOutputDir(workingDir, directory)
@@ -73,3 +69,10 @@ func TestResolveOutputDirAllowsMissingDirectoryBelowValidSymlink(t *testing.T) {
 		t.Fatalf("resolveOutputDir() = %q, %v, want %q, nil", got, err, directory)
 	}
 }
+
+func requireSymlink(t *testing.T, target string, link string) {
+	t.Helper()
+	if err := os.Symlink(target, link); err != nil {
+		t.Skipf("symlink support is unavailable: %v", err)
+	}
+}