generate: Fix testGenerateRun so that it actually works

.gitignore

@@ -0,0 +1 @@
+/generate/test

generate/misc_test.go

@@ -7,10 +7,14 @@ import "testing"
 import "path/filepath"
 
 func testGenerateRun(test *testing.T, protocol *Protocol, imports string, testCase string) {
-	// open files
+	// reset data directory
-	dir, err := os.MkdirTemp(os.TempDir(), "hopp-generate-test-*")
+	dir := "test/generate-run"
+	err := os.RemoveAll(dir)
 	if err != nil { test.Fatal(err) }
-	defer os.RemoveAll(dir)
+	err = os.MkdirAll(dir, 0750)
+	if err != nil { test.Fatal(err) }
+
+	// open files
 	sourceFile, err := os.Create(filepath.Join(dir, "protocol.go"))
 	if err != nil { test.Fatal(err) }
 	defer sourceFile.Close()
@@ -29,15 +33,37 @@ func testGenerateRun(test *testing.T, protocol *Protocol, imports string, testCa
 	// build static source files
 	imports = `
 		import "log"
+		import "bytes"
+		import "slices"
+		import "git.tebibyte.media/sashakoshka/hopp/tape"
 		` + imports
 	setup := `log.Println("*** BEGIN TEST CASE OUTPUT ***")`
 	teardown := `log.Println("--- END TEST CASE OUTPUT ---")`
+	static := `
+		func testEncode(message Message, correct ...byte) {
+			buffer := bytes.Buffer { }
+			encoder := tape.NewEncoder(&buffer)
+			n, err := message.Encode(encoder)
+			if err != nil { log.Fatalf("at %d: %v\n", n, err) }
+			got := buffer.Bytes()
+			if n != len(got) {
+				log.Fatalln("len incorrect: %d != %d", got, correct)
+			}
+			if !slices.Equal(got, correct) {
+				log.Fatalln("not equal:")
+			}
+		}
+		`
 	fmt.Fprintf(
-		mainFile, "package main\n%s\nfunc main() {%s\n%s\n%s\n}\n",
+		mainFile, "package main\n%s\nfunc main() {\n%s\n%s\n%s\n}\n%s",
-		imports, setup, testCase, teardown)
+		imports, setup, testCase, teardown, static)
 
 	// build and run test
-	command := exec.Command("go", "run", filepath.Join(dir, "main.go"))
+	command := exec.Command("go", "run", "./generate/test/generate-run")
+	workingDirAbs, err := filepath.Abs("..")
+	if err != nil { test.Fatal(err) }
+	command.Dir = workingDirAbs
+	command.Env = os.Environ()
 	output, err := command.CombinedOutput()
 	test.Logf("output of %v:\n%s", command, output)
 	if err != nil { test.Fatal(err) }