Complete diagnostics retention semantics

internal/core/diagnostics/retention_test.go

@@ -0,0 +1,72 @@
+package diagnostics
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestShouldRetainRunDirectoryMatrix(t *testing.T) {
+	tests := []struct {
+		name  string
+		input RetentionDecisionInput
+		want  bool
+	}{
+		{name: "always success keeps", input: RetentionDecisionInput{RetentionMode: "always", RunSucceeded: true}, want: true},
+		{name: "always failure keeps", input: RetentionDecisionInput{RetentionMode: "always", RunSucceeded: false}, want: true},
+		{name: "never success keeps", input: RetentionDecisionInput{RetentionMode: "never", RunSucceeded: true}, want: true},
+		{name: "never failure keeps", input: RetentionDecisionInput{RetentionMode: "never", RunSucceeded: false}, want: true},
+		{name: "auto success no skips removes", input: RetentionDecisionInput{RetentionMode: "auto", RunSucceeded: true, HasSkippedCorrections: false}, want: false},
+		{name: "auto success skips keeps", input: RetentionDecisionInput{RetentionMode: "auto", RunSucceeded: true, HasSkippedCorrections: true}, want: true},
+		{name: "auto failure keeps", input: RetentionDecisionInput{RetentionMode: "auto", RunSucceeded: false}, want: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := ShouldRetainRunDirectory(tc.input)
+			if got != tc.want {
+				t.Fatalf("unexpected retain decision: got=%v want=%v", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestApplyRetentionRemovesWhenDecisionSaysRemove(t *testing.T) {
+	workDir := t.TempDir()
+	runPath := filepath.Join(workDir, "run-test")
+	if err := os.Mkdir(runPath, 0o755); err != nil {
+		t.Fatalf("mkdir run path: %v", err)
+	}
+
+	runDir := &RunDirectory{path: runPath, retention: "auto"}
+	err := runDir.ApplyRetention(RetentionDecisionInput{RunSucceeded: true, HasSkippedCorrections: false})
+	if err != nil {
+		t.Fatalf("ApplyRetention failed: %v", err)
+	}
+
+	if _, err := os.Stat(runPath); !os.IsNotExist(err) {
+		t.Fatalf("expected run directory removed, stat err=%v", err)
+	}
+}
+
+func TestApplyRetentionReturnsRemovalError(t *testing.T) {
+	parent := t.TempDir()
+	runPath := filepath.Join(parent, "run-test")
+	if err := os.Mkdir(runPath, 0o755); err != nil {
+		t.Fatalf("mkdir run path: %v", err)
+	}
+
+	// Make parent non-writable so removing child fails.
+	if err := os.Chmod(parent, 0o500); err != nil {
+		t.Fatalf("chmod parent: %v", err)
+	}
+	t.Cleanup(func() {
+		_ = os.Chmod(parent, 0o700)
+	})
+
+	runDir := &RunDirectory{path: runPath, retention: "auto"}
+	err := runDir.ApplyRetention(RetentionDecisionInput{RunSucceeded: true, HasSkippedCorrections: false})
+	if err == nil {
+		t.Fatalf("expected removal error, got nil")
+	}
+}