gopls/internal/golang: Disable test generation for generic functions

For golang/vscode-go#1594

Change-Id: I8563e4cde1606a23a402bc2154b1af69cb9ff724
Reviewed-on: https://go-review.googlesource.com/c/tools/+/632857
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

Author: h9jiang

gopls/internal/golang/codeaction.go

@@ -504,6 +504,11 @@ func addTest(ctx context.Context, req *codeActionsRequest) error {
 		return nil
 	}
 
+	// TODO(hxjiang): support functions with type parameter.
+	if decl.Type.TypeParams != nil {
+		return nil
+	}
+
 	cmd := command.NewAddTestCommand("Add test for "+decl.Name.String(), req.loc)
 	req.addCommandAction(cmd, true)
 

gopls/internal/test/marker/testdata/codeaction/addtest.txt

@@ -1530,3 +1530,13 @@ var local renamedctx.Context
 +		})
 +	}
 +}
+-- typeparameter/typeparameter.go --
+package main
+
+func Function[T any] () {} // no suggested fix
+
+type Foo struct {}
+
+func NewFoo()
+
+func (*Foo) Method[T any]() {} // no suggested fix