test(tui): add tier 1 unit tests for pure logic functions

Cover search filtering, intent matching, card affordances, checklist
parsing, template slot discovery/resolve, date grouping, and truncation.

internal/tui/search_test.go

@@ -0,0 +1,70 @@
+package tui
+
+import (
+	"testing"
+
+	"github.com/lerko/nib/internal/db"
+)
+
+func ptr[T any](v T) *T { return &v }
+
+func TestFilterEntities(t *testing.T) {
+	entities := []*db.Entity{
+		{ID: "1", Body: "buy groceries", Tags: []string{"errand", "food"}},
+		{ID: "2", Body: "read chapter 5", Title: ptr("Go Book"), Tags: []string{"study"}},
+		{ID: "3", Body: "fix login bug", Description: ptr("auth middleware broken"), Tags: []string{"work", "urgent"}},
+		{ID: "4", Body: "empty tags"},
+	}
+
+	tests := []struct {
+		name    string
+		query   string
+		tags    []string
+		wantIDs []string
+	}{
+		{"no filter returns all", "", nil, []string{"1", "2", "3", "4"}},
+		{"query matches body", "groceries", nil, []string{"1"}},
+		{"query case insensitive", "GROCERIES", nil, []string{"1"}},
+		{"query matches title", "go book", nil, []string{"2"}},
+		{"query matches description", "middleware", nil, []string{"3"}},
+		{"query no match", "nonexistent", nil, nil},
+		{"single tag filter", "", []string{"study"}, []string{"2"}},
+		{"multi tag filter all present", "", []string{"work", "urgent"}, []string{"3"}},
+		{"multi tag filter partial miss", "", []string{"work", "food"}, nil},
+		{"tag filter no match", "", []string{"missing"}, nil},
+		{"query plus tag", "fix", []string{"work"}, []string{"3"}},
+		{"query plus tag mismatch", "groceries", []string{"work"}, nil},
+		{"entity with nil title and description", "empty", nil, []string{"4"}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := filterEntities(entities, tt.query, tt.tags)
+			gotIDs := make([]string, len(got))
+			for i, e := range got {
+				gotIDs[i] = e.ID
+			}
+			if len(tt.wantIDs) == 0 && len(gotIDs) == 0 {
+				return
+			}
+			if len(gotIDs) != len(tt.wantIDs) {
+				t.Fatalf("got %v, want %v", gotIDs, tt.wantIDs)
+			}
+			for i := range gotIDs {
+				if gotIDs[i] != tt.wantIDs[i] {
+					t.Fatalf("got %v, want %v", gotIDs, tt.wantIDs)
+				}
+			}
+		})
+	}
+}
+
+func TestMatchesSearch_NilFields(t *testing.T) {
+	e := &db.Entity{Body: "hello world"}
+	if !matchesSearch(e, "hello", nil) {
+		t.Fatal("should match body")
+	}
+	if matchesSearch(e, "title", nil) {
+		t.Fatal("should not match nil title")
+	}
+}