test: expand coverage across readers, writers, cmd, ui, diff and merge

Implements tests/_plans and previously deferred packages; updates plan
README with new coverage numbers.

pkg/transform/transform_test.go

@@ -0,0 +1,38 @@
+package transform
+
+import (
+	"testing"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+)
+
+// Validation and normalization are currently pass-through stubs; these tests
+// pin that contract (no error, input returned unchanged).
+func TestTransformerStubs(t *testing.T) {
+	tr := NewTransformer()
+	if tr == nil {
+		t.Fatal("nil transformer")
+	}
+	db := models.InitDatabase("d")
+	schema := models.InitSchema("public")
+	table := models.InitTable("t", "public")
+
+	if err := tr.ValidateDatabase(db); err != nil {
+		t.Error(err)
+	}
+	if err := tr.ValidateSchema(schema); err != nil {
+		t.Error(err)
+	}
+	if err := tr.ValidateTable(table); err != nil {
+		t.Error(err)
+	}
+	if got, err := tr.NormalizeDatabase(db); err != nil || got != db {
+		t.Errorf("NormalizeDatabase = %v, %v", got, err)
+	}
+	if got, err := tr.NormalizeSchema(schema); err != nil || got != schema {
+		t.Errorf("NormalizeSchema = %v, %v", got, err)
+	}
+	if got, err := tr.NormalizeTable(table); err != nil || got != table {
+		t.Errorf("NormalizeTable = %v, %v", got, err)
+	}
+}