explain walks the directory for a duplicate test in an exclude too

2 files changed, 44 insertions, 3 deletions

diff --git a/internal/engine/exclude_test.go b/internal/engine/exclude_test.go
index 5a758bb..9aafd7f 100644
--- a/internal/engine/exclude_test.go
+++ b/internal/engine/exclude_test.go
@@ -483,3 +483,32 @@ func TestPartlyReadableDocumentIsNotCached(t *testing.T) {
 		}
 	}
 }
+
+// TestExplainAgreesWithMatchOnADuplicateExclude: a (duplicate) test inside
+// an exclude needs the directory's other files, as one inside a rule does,
+// so explain sets aside exactly the files Match does (plan 11 review M3).
+func TestExplainAgreesWithMatchOnADuplicateExclude(t *testing.T) {
+	h, dl := excludeTree(t, map[string]string{"a.txt": "same", "b.txt": "same", "c.txt": "other"})
+	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": `
+(path "~/dl")
+(exclude (not (duplicate)))
+(rule "all" (move "Out"))
+`})
+	e, errs := Load(main)
+	if len(errs) > 0 {
+		t.Fatal(errs)
+	}
+	r, err := e.Match(context.Background(), e.Dirs[0])
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, fm := range append(append([]FileMatch{}, r.Matched...), r.Unmatched...) {
+		x, err := e.Explain(context.Background(), filepath.Join(dl, fm.File.Rel))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if x.Excluded != fm.Excluded {
+			t.Errorf("%s: explain sets it aside as %q, Match as %q", fm.File.Rel, x.Excluded, fm.Excluded)
+		}
+	}
+}
diff --git a/internal/engine/match.go b/internal/engine/match.go
index 6b98d73..c252596 100644
--- a/internal/engine/match.go
+++ b/internal/engine/match.go
@@ -280,10 +280,11 @@ func (e *Engine) Explain(ctx context.Context, path string) (*Explanation, error)
 	excl := e.excludeDirs(d)
 	skip := explainSkip(d, sf, excl, now)
 
-	// The directory is walked only for a duplicate test, the one thing that
-	// needs its other files (triage 21).
+	// The directory is walked only for a duplicate test - in a rule or in an
+	// exclude - the one thing that needs its other files (triage 21, plan 11
+	// review M3).
 	files := []scan.File{sf}
-	if len(d.DupScopes) > 0 {
+	if len(d.DupScopes) > 0 || excludesUseDuplicate(d) {
 		files = e.filesForExplain(d, sf, excl, now)
 	}
 	run := newMatchRun(e, d, ctx, now, files)
@@ -332,6 +333,17 @@ func (e *Engine) Explain(ctx context.Context, path string) (*Explanation, error)
 	return &Explanation{Dir: d, File: sf, Skip: skip, Excludes: excludes, Excluded: excluded, Rules: rules, NoDelete: noDel}, nil
 }
 
+// excludesUseDuplicate reports whether any of d's excludes has a
+// (duplicate) test.
+func excludesUseDuplicate(d *Dir) bool {
+	for _, x := range d.Excludes {
+		if len(x.Cond.DupDirs) > 0 {
+			return true
+		}
+	}
+	return false
+}
+
 // cacheFingerprint identifies what a cached keyword answer of d depends on
 // besides the file: the extractor (its version and tools), normalisation
 // and its Unicode tables, the Go release, and d's max-read, which caps what