Add matchers for gomega assertion library

Author: stroiman

testing/matchers/package.go

@@ -0,0 +1,34 @@
+// Package matchers contain matchers for use with the [gomega] assertion library.
+package matchers
+
+import (
+	"bytes"
+
+	"github.com/gost-dom/generators"
+	"github.com/onsi/gomega"
+	"github.com/onsi/gomega/types"
+)
+
+func render(g generators.Generator) (string, error) {
+	var b bytes.Buffer
+	err := g.Generate().Render(&b)
+	return b.String(), err
+}
+
+// HaveRendered returns a [types.GomegaMatcher] that matches string rendered
+// statement against another GomegaMatcher. If the expected value is not a
+// GomegaMatcher, it will implicitly match for equality using [gomega.Equal].
+func HaveRendered(expected interface{}) types.GomegaMatcher {
+	matcher, ok := expected.(types.GomegaMatcher)
+	if !ok {
+		return HaveRendered(gomega.Equal(expected))
+	}
+	return gomega.WithTransform(render, matcher)
+}
+
+// HaveRenderedSubstring is simple helper for [HaveRendered] for a very common
+// use case to test for the presence of a substrubg in the rendered statement.
+// Short for HaveRendered(gomega.ContainSubstring(expected)).
+func HaveRenderedSubstring(expected string) types.GomegaMatcher {
+	return HaveRendered(gomega.ContainSubstring(expected))
+}

testing/matchers/package_test.go

@@ -0,0 +1,30 @@
+package matchers_test
+
+import (
+	"testing"
+
+	gen "github.com/gost-dom/generators"
+	. "github.com/gost-dom/generators/testing/matchers"
+
+	"github.com/onsi/gomega"
+)
+
+func TestHaveRendered(t *testing.T) {
+	g := gomega.NewWithT(t)
+	x := gen.NewValue("x")
+	expr := gen.Assign(x, gen.Lit(42))
+	g.Expect(HaveRendered("x := 42").Match(expr)).To(gomega.BeTrue())
+	g.Expect(HaveRendered("y := 42").Match(expr)).To(gomega.BeFalse())
+	g.Expect(HaveRendered("x := 43").Match(expr)).To(gomega.BeFalse())
+
+	compoundExpr := gen.StatementList(expr, gen.Return(x.Field("String").Call()))
+	g.Expect(HaveRendered("x := 42").Match(compoundExpr)).To(gomega.BeFalse())
+	g.Expect(HaveRendered("x := 42\nreturn x.String()").Match(compoundExpr)).To(gomega.BeTrue())
+	g.Expect(HaveRenderedSubstring("x := 42").Match(compoundExpr)).To(gomega.BeTrue())
+	g.Expect(HaveRendered(gomega.ContainSubstring("x := 42")).Match(compoundExpr)).
+		To(gomega.BeTrue())
+	g.Expect(HaveRendered(gomega.MatchRegexp(`x := \d{2}`)).Match(compoundExpr)).
+		To(gomega.BeTrue())
+	g.Expect(HaveRendered(gomega.MatchRegexp(`x := \d{3}`)).Match(compoundExpr)).
+		To(gomega.BeFalse())
+}