test: cover Windows classification and refresh saved outputs

examples/README.md

@@ -20,3 +20,5 @@ Real output from `godebugdiff` with no flags, on Go 1.27.3, on shallow clones of
 | `rclone.txt` | github.com/rclone/rclone | `f0cb5dd` | MIT |
 
 To redo one: clone the project, check out the commit, run `go mod download`, then `go run ./plugin/scripts PATH` from this repo. The results depend on the toolchain you run.
+
+The shop output and `cobra.txt` were regenerated on 2026-11-15 with Go 1.27.4. The Cobra checkout remains at the commit listed above; other saved real-project outputs retain their original toolchain.

examples/real/cobra.txt

@@ -1,4 +1,4 @@
-go 1.15 -> 1.27 in github.com/spf13/cobra (go1.27.3, 2 test binaries)
+go 1.15 -> 1.27 in github.com/spf13/cobra (go1.27.4, 2 test binaries)
 
 28 GODEBUG defaults change. 13 reach a package your test binaries import.
 
@@ -12,12 +12,12 @@ panicnil  1 -> default  Go 1.21, runtime
     Go 1.21 made it a run-time error to call panic with a nil interface value, controlled by the panicnil setting.
     https://go.dev/doc/godebug#go-121
 
-winreadlinkvolume  0 -> default  Go 1.23, os
+winreadlinkvolume  0 -> default  Go 1.23, os (Windows only)
     imported by all 2 test binaries
     Go 1.23 changed os.Readlink and filepath.EvalSymlinks to avoid trying to normalize volumes to drive letters, which was not always even possible.
     https://go.dev/doc/godebug#go-123
 
-winsymlink  0 -> default  Go 1.23, os
+winsymlink  0 -> default  Go 1.23, os (Windows only)
     imported by all 2 test binaries
     Go 1.23 changed the mode bits reported by os.Lstat and os.Stat for reparse points, which can be controlled with the winsymlink setting.
     https://go.dev/doc/godebug#go-123

examples/shop-1.21-to-1.24.txt

@@ -1,4 +1,4 @@
-go 1.21 -> 1.24 in example.com/shop (go1.27.3, 2 binaries)
+go 1.21 -> 1.24 in example.com/shop (go1.27.4, 2 binaries)
 
 15 GODEBUG defaults change. 14 reach a package your binaries import.
 
@@ -17,12 +17,12 @@ httpservecontentkeepheaders  1 -> default  Go 1.23, net/http
     Go 1.23 changed net/http.ServeContent, net/http.ServeFile, and net/http.ServeFS to remove Cache-Control, Content-Encoding, Etag, and Last-Modified headers when serving an error.
     https://go.dev/doc/godebug#go-123
 
-winreadlinkvolume  0 -> default  Go 1.23, os
+winreadlinkvolume  0 -> default  Go 1.23, os (Windows only)
     imported by all 2 binaries
     Go 1.23 changed os.Readlink and filepath.EvalSymlinks to avoid trying to normalize volumes to drive letters, which was not always even possible.
     https://go.dev/doc/godebug#go-123
 
-winsymlink  0 -> default  Go 1.23, os
+winsymlink  0 -> default  Go 1.23, os (Windows only)
     imported by all 2 binaries
     Go 1.23 changed the mode bits reported by os.Lstat and os.Stat for reparse points, which can be controlled with the winsymlink setting.
     https://go.dev/doc/godebug#go-123

plugin/scripts/godebugdiff.go

@@ -67,7 +67,7 @@ type Change struct {
 	After       string   `json:"after"`
 	ReachedBy   []string `json:"reachedBy"`             // binaries that import Package
 	GoCommand   bool     `json:"goCommand"`             // the setting controls the go command, not binaries
-	WindowsOnly bool     `json:"windowsOnly,omitempty"` // name starts with win; Linux services can skip
+	WindowsOnly bool     `json:"windowsOnly,omitempty"` // Windows-specific setting; relevance depends on the deployment platform
 	Doc         string   `json:"doc,omitempty"`
 	URL         string   `json:"url,omitempty"`
 }

plugin/scripts/godebugdiff_test.go

@@ -273,3 +273,24 @@ func TestWindowsOnly(t *testing.T) {
 		t.Fatalf("JSON missing windowsOnly: %s", enc)
 	}
 }
+
+func TestCompareWindowsOnly(t *testing.T) {
+	before := []Binary{{ImportPath: "example.com/app", Godebug: parseGodebug("winreadlinkvolume=0,httpmuxgo121=1"), Deps: map[string]bool{"os": true, "net/http": true}}}
+	after := []Binary{{ImportPath: "example.com/app", Godebug: parseGodebug(""), Deps: map[string]bool{"os": true, "net/http": true}}}
+	table := map[string]Setting{
+		"winreadlinkvolume": {Name: "winreadlinkvolume", Package: "os", Changed: 26, Old: "0"},
+		"httpmuxgo121":      {Name: "httpmuxgo121", Package: "net/http", Changed: 22, Old: "1"},
+	}
+	changes, _ := compare(before, after, table, nil)
+	if len(changes) != 2 {
+		t.Fatalf("changes: %+v", changes)
+	}
+	for _, c := range changes {
+		if c.WindowsOnly != (c.Name == "winreadlinkvolume") {
+			t.Errorf("platform classification: %+v", c)
+		}
+		if !reflect.DeepEqual(c.ReachedBy, []string{"example.com/app"}) {
+			t.Errorf("reachedBy: %+v", c)
+		}
+	}
+}