test: allow fetching CRD from a local replace statement

Ginkgo test suites require fetching the CRDs of the custom resources
used in the tests. Those are fetched from the go.mod and any replace
statement is parsed and honoured.
Add the ability to process replace statements that point to a local
directory as well, to ease the developement process when a project
depends on a feature from another project that has not been merged yet.

modules/test/crd.go

@@ -18,6 +18,7 @@ import (
 	"go/build"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"golang.org/x/mod/modfile"
 )
@@ -53,10 +54,16 @@ func getDependencyVersion(moduleName string, goModPath string) (string, string,
 		}
 	}
 
+	// replacement points to a URI + version
 	if version != "" {
 		return name, version, nil
 	}
 
+	// replacement points to a local path
+	if version == "" && strings.HasPrefix(name, ".") {
+		return name, version, nil
+	}
+
 	return name, "", fmt.Errorf("cannot find %s in %s file", moduleName, goModPath)
 }
 
@@ -68,6 +75,15 @@ func GetCRDDirFromModule(moduleName string, goModPath string, relativeCRDPath st
 	if err != nil {
 		return "", err
 	}
+
+	// for a local replacement, assume the CRDs are available in the
+	// standard Operator SDK's layout
+	if version == "" && strings.HasPrefix(moduleName, ".") {
+		goModDir := filepath.Dir(goModPath)
+		path := filepath.Join(goModDir, moduleName, "..", "config", "crd", relativeCRDPath)
+		return path, nil
+	}
+
 	versionedModule := fmt.Sprintf("%s@%s", moduleName, version)
 	path := filepath.Join(build.Default.GOPATH, "pkg", "mod", versionedModule, relativeCRDPath)
 	return path, nil