Share D&D cited source traversal

internal/modules/dnd/shared/citations_test.go

@@ -0,0 +1,87 @@
+package shared
+
+import (
+	"reflect"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+)
+
+func TestCitedText(t *testing.T) {
+	doc := citationDocument()
+	tests := []struct {
+		name    string
+		refs    []source.SourceRef
+		want    string
+		wantErr bool
+	}{
+		{name: "empty references", refs: nil, want: ""},
+		{name: "invalid source id", refs: []source.SourceRef{{SourceID: "other", StartUnitID: 10, EndUnitID: 10}}, wantErr: true},
+		{name: "unknown start unit", refs: []source.SourceRef{{SourceID: "session", StartUnitID: 99, EndUnitID: 10}}, wantErr: true},
+		{name: "unknown end unit", refs: []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 99}}, wantErr: true},
+		{name: "reversed document range", refs: []source.SourceRef{{SourceID: "session", StartUnitID: 30, EndUnitID: 10}}, wantErr: true},
+		{
+			name: "disjoint ranges supplied out of order",
+			refs: []source.SourceRef{
+				{SourceID: "session", StartUnitID: 30, EndUnitID: 30},
+				{SourceID: "session", StartUnitID: 10, EndUnitID: 10},
+			},
+			want: "alpha\ngamma",
+		},
+		{
+			name: "adjacent ranges",
+			refs: []source.SourceRef{
+				{SourceID: "session", StartUnitID: 10, EndUnitID: 20},
+				{SourceID: "session", StartUnitID: 30, EndUnitID: 40},
+			},
+			want: "alpha\nbeta\ngamma\ndelta",
+		},
+		{
+			name: "overlapping and duplicate ranges",
+			refs: []source.SourceRef{
+				{SourceID: "session", StartUnitID: 10, EndUnitID: 30},
+				{SourceID: "session", StartUnitID: 20, EndUnitID: 40},
+				{SourceID: "session", StartUnitID: 10, EndUnitID: 30},
+			},
+			want: "alpha\nbeta\ngamma\ndelta",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			beforeUnits := append([]source.SourceUnit(nil), doc.Units...)
+			refs := append([]source.SourceRef(nil), test.refs...)
+			got, err := CitedText(doc, refs)
+			if (err != nil) != test.wantErr {
+				t.Fatalf("CitedText() error = %v, want error = %t", err, test.wantErr)
+			}
+			if err == nil && got != test.want {
+				t.Fatalf("CitedText() = %q, want %q", got, test.want)
+			}
+			if !reflect.DeepEqual(doc.Units, beforeUnits) || !reflect.DeepEqual(refs, test.refs) {
+				t.Fatalf("CitedText() mutated document or references")
+			}
+		})
+	}
+}
+
+func TestCitedTextRejectsNilDocument(t *testing.T) {
+	if _, err := CitedText(nil, nil); err == nil {
+		t.Fatal("CitedText() error = nil, want nil-document error")
+	}
+}
+
+func citationDocument() *source.SourceDocument {
+	return &source.SourceDocument{
+		ID:     "session",
+		Kind:   "transcript",
+		Format: "application/json",
+		Digest: "sha256:session",
+		Units: []source.SourceUnit{
+			{ID: 10, Kind: "message", Text: "alpha"},
+			{ID: 20, Kind: "message", Text: "beta"},
+			{ID: 30, Kind: "message", Text: "gamma"},
+			{ID: 40, Kind: "message", Text: "delta"},
+		},
+	}
+}