Restore cancellation checks before report delivery

integrations/ckconfig/diff.go

@@ -3,7 +3,6 @@ package ckconfig
 import (
 	"errors"
 	"fmt"
-	"io"
 
 	commandkit "gitea.maximumdirect.net/eric/CommandKit"
 )
@@ -31,16 +30,7 @@ func runConfigDiff[I, S any](invocation commandkit.Invocation, plan *configOpera
 	if err := invocation.Context.Err(); err != nil {
 		return configFailure("Configuration comparison was canceled.", acquired.Explanation, err)
 	}
-	err = reporter.RenderOutput(func(writer io.Writer) error {
-		report, err := renderDiffReport(acquired.Value)
-		if err != nil {
-			return err
-		}
-		_, err = writer.Write(report)
-		return err
+	return renderPreparedConfigReport(invocation, acquired.Explanation, func() ([]byte, error) {
+		return renderDiffReport(acquired.Value)
 	})
-	if err != nil && invocation.Context.Err() != nil {
-		return configFailure("Configuration comparison was canceled.", acquired.Explanation, invocation.Context.Err())
-	}
-	return commandkit.Success()
 }

integrations/ckconfig/explain.go

@@ -94,18 +94,13 @@ func runConfigExplanation[I, S any](invocation commandkit.Invocation, plan *conf
 		}
 		return commandkit.Success()
 	}
-	err := reporter.RenderOutput(func(writer io.Writer) error {
+	return renderPreparedConfigReport(invocation, acquired.Explanation, func() ([]byte, error) {
 		var report bytes.Buffer
 		if err := encodeYAML(&report, makeExplanationReport(name, explanation)); err != nil {
-			return err
+			return nil, err
 		}
-		_, err := writer.Write(report.Bytes())
-		return err
+		return report.Bytes(), nil
 	})
-	if err != nil && invocation.Context.Err() != nil {
-		return configFailure("Configuration explanation was canceled.", acquired.Explanation, invocation.Context.Err())
-	}
-	return commandkit.Success()
 }
 
 func makeExplanationReport(scope string, explanation configkit.Explanation) explanationReport {

integrations/ckconfig/operations.go

@@ -2,6 +2,7 @@ package ckconfig
 
 import (
 	"fmt"
+	"io"
 
 	commandkit "gitea.maximumdirect.net/eric/CommandKit"
 )
@@ -74,3 +75,26 @@ func configAcquisitionFailure(
 	message := fmt.Sprintf("Unable to %s configuration scope %q.", operation, scope)
 	return configFailure(message, acquired.Explanation, cause)
 }
+
+// Preserve the preparation/delivery cancellation checkpoint for buffered reports.
+func renderPreparedConfigReport(invocation commandkit.Invocation, explanation commandkit.Explanation, prepare func() ([]byte, error)) commandkit.Outcome {
+	var canceled error
+	renderErr := invocation.Reporter().RenderOutput(func(writer io.Writer) error {
+		report, err := prepare()
+		if err != nil {
+			return err
+		}
+		if canceled = invocation.Context.Err(); canceled != nil {
+			return nil
+		}
+		_, err = writer.Write(report)
+		return err
+	})
+	if canceled == nil && renderErr != nil {
+		canceled = invocation.Context.Err()
+	}
+	if canceled != nil {
+		return configFailure("Configuration report preparation was canceled.", explanation, canceled)
+	}
+	return commandkit.Success()
+}

integrations/ckconfig/report_cancellation_test.go

@@ -0,0 +1,69 @@
+package ckconfig
+
+import (
+	"context"
+	"errors"
+	"io"
+	"testing"
+
+	commandkit "gitea.maximumdirect.net/eric/CommandKit"
+)
+
+func TestBufferedReportCancellationBeforeDelivery(t *testing.T) {
+	for _, quiet := range []bool{false, true} {
+		t.Run(map[bool]string{false: "ordinary", true: "quiet"}[quiet], func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+			prepared := false
+			app := newConfigTestApp(t, commandkit.NewCommand(commandkit.CommandSpec[struct{}]{
+				Name: "report",
+				Run: func(invocation commandkit.Invocation, _ struct{}) commandkit.Outcome {
+					return renderPreparedConfigReport(invocation, commandkit.Explanation{Message: "selected context"}, func() ([]byte, error) {
+						prepared = true
+						cancel()
+						return []byte("prepared report"), nil
+					})
+				},
+			}))
+			args := []string{"report"}
+			if quiet {
+				args = append(args, "--quiet")
+			}
+			writes := 0
+			got := app.Execute(ctx, args, commandkit.Streams{Out: reportWriteFunc(func(p []byte) (int, error) {
+				writes++
+				return len(p), nil
+			})})
+			if !prepared || writes != 0 || got.Status != 1 || !errors.Is(got.Cause, context.Canceled) || got.Explanation.Message != "selected context" {
+				t.Fatalf("prepared=%t writes=%d outcome=%#v", prepared, writes, got)
+			}
+			if got.Presentation.Output.RenderError != nil || got.Presentation.Output.WriteError != nil {
+				t.Fatalf("cancellation became a presentation failure: %#v", got.Presentation.Output)
+			}
+		})
+	}
+}
+
+type reportWriteFunc func([]byte) (int, error)
+
+func (write reportWriteFunc) Write(p []byte) (int, error) { return write(p) }
+
+func TestBufferedReportDoesNotRejectCancellationAfterDeliveryStarts(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	app := newConfigTestApp(t, commandkit.NewCommand(commandkit.CommandSpec[struct{}]{
+		Name: "report",
+		Run: func(invocation commandkit.Invocation, _ struct{}) commandkit.Outcome {
+			return renderPreparedConfigReport(invocation, commandkit.Explanation{}, func() ([]byte, error) {
+				return []byte("report"), nil
+			})
+		},
+	}))
+	got := app.Execute(ctx, []string{"report"}, commandkit.Streams{Out: reportWriteFunc(func(p []byte) (int, error) {
+		cancel()
+		return io.Discard.Write(p)
+	})})
+	if got.Status != 0 || got.Cause != nil {
+		t.Fatalf("post-delivery cancellation changed the operation outcome: %#v", got)
+	}
+}

integrations/ckconfig/sources.go

@@ -117,22 +117,17 @@ func runConfigSources[I, S any](invocation commandkit.Invocation, plan *configOp
 	if err := invocation.Context.Err(); err != nil {
 		return configFailure("Configuration source listing was canceled.", acquired.Explanation, err)
 	}
-	err := reporter.RenderOutput(func(writer io.Writer) error {
+	return renderPreparedConfigReport(invocation, acquired.Explanation, func() ([]byte, error) {
 		var report bytes.Buffer
 		if plan.format == "yaml" {
 			if err := encodeYAML(&report, document); err != nil {
-				return err
+				return nil, err
 			}
 		} else {
 			writeSourceReportText(&report, document)
 		}
-		_, err := writer.Write(report.Bytes())
-		return err
+		return report.Bytes(), nil
 	})
-	if err != nil && invocation.Context.Err() != nil {
-		return configFailure("Configuration source listing was canceled.", acquired.Explanation, invocation.Context.Err())
-	}
-	return commandkit.Success()
 }
 
 func writeSourceReportText(writer *bytes.Buffer, document sourceReport) {