plugin/discovery: handle the -Xn suffix used by auto-installed plugins

This is used to mark the plugin protocol version. Currently we actually
just ignore this entirely, since only one protocol version exists anyway.
Later we will need to add checks here to ensure that we only pay attention
to plugins of the right version.

plugin/discovery/find.go

@@ -147,6 +147,12 @@ func ResolvePluginPaths(paths []string) PluginMetaSet {
 			version = parts[1]
 		}
 
+		// Auto-installed plugins contain an extra name portion representing
+		// the expected plugin version, which we must trim off.
+		if dashX := strings.Index(version, "-X"); dashX != -1 {
+			version = version[:dashX]
+		}
+
 		if _, ok := found[nameVersion{name, version}]; ok {
 			// Skip duplicate versions of the same plugin
 			// (We do this during this step because after this we will be

plugin/discovery/find_test.go

@@ -53,6 +53,7 @@ func TestResolvePluginPaths(t *testing.T) {
 		"/example/mockos_mockarch/terraform-foo-bar-V0.0.1",
 		"/example/mockos_mockarch/terraform-foo-baz-V0.0.1",
 		"/example/mockos_mockarch/terraform-foo-baz-V1.0.0",
+		"/example/mockos_mockarch/terraform-foo-baz-V2.0.0-X4",
 		"/example/terraform-foo-bar",
 		"/example/mockos_mockarch/terraform-foo-bar-Vbananas",
 		"/example/mockos_mockarch/terraform-foo-bar-V",
@@ -75,6 +76,11 @@ func TestResolvePluginPaths(t *testing.T) {
 			Version: "1.0.0",
 			Path:    "/example/mockos_mockarch/terraform-foo-baz-V1.0.0",
 		},
+		{
+			Name:    "baz",
+			Version: "2.0.0",
+			Path:    "/example/mockos_mockarch/terraform-foo-baz-V2.0.0-X4",
+		},
 		{
 			Name:    "bar",
 			Version: "0.0.0",
@@ -92,6 +98,8 @@ func TestResolvePluginPaths(t *testing.T) {
 		},
 	}
 
+	t.Logf("got %#v", got)
+
 	if got, want := got.Count(), len(want); got != want {
 		t.Errorf("got %d items; want %d", got, want)
 	}