chore: convert build_go_test into an integration test

internal/buildengine/build_go_integration_test.go

@@ -0,0 +1,56 @@
+//go:build integration
+
+package buildengine
+
+import (
+	"os"
+	"testing"
+
+	"github.com/alecthomas/assert/v2"
+
+	in "github.com/TBD54566975/ftl/internal/integration"
+)
+
+func TestGoBuildClearsBuildDir(t *testing.T) {
+	file := "another/.ftl/test-clear-build.tmp"
+	in.Run(t,
+		in.WithTestDataDir("testdata"),
+		in.CopyModule("another"),
+		in.WriteFile(file, []byte{1}),
+		in.FileExists(file),
+		in.Build("another"),
+		in.ExpectError(in.FileExists(file), "no such file"),
+	)
+}
+
+func TestExternalType(t *testing.T) {
+	in.Run(t,
+		in.WithTestDataDir("testdata"),
+		in.CopyModule("external"),
+		in.ExpectError(in.Build("external"),
+			`unsupported type "time.Month" for field "Month"`,
+			`unsupported external type "time.Month"; see FTL docs on using external types: tbd54566975.github.io/ftl/docs/reference/externaltypes/`,
+			`unsupported response type "ftl/external.ExternalResponse"`,
+		),
+	)
+}
+
+func TestGeneratedTypeRegistry(t *testing.T) {
+	expected, err := os.ReadFile("testdata/type_registry_main.go")
+	assert.NoError(t, err)
+
+	file := "other/.ftl/go/main/main.go"
+
+	in.Run(t,
+		in.WithTestDataDir("testdata"),
+		// Deploy dependency
+		in.CopyModule("another"),
+		in.Deploy("another"),
+		// Build the module under test
+		in.CopyModule("other"),
+		in.ExpectError(in.FileExists(file), "no such file"),
+		in.Build("other"),
+		// Validate the generated main.go
+		in.FileContent(file, string(expected)),
+	)
+}