如何将两个数据框与一些条件要求合并在一起？

我有两个数据框df1和df2. 我想在以下条件下加入两者：

1. 合并 df1 和 df2gender和Test
2. TestDatedf1需要在里面Date1和Date2从df2
3. all.x = TRUE（保留 df1 记录）

我不确定如何处理第二部分。有人可以指导我这部分吗？

df1 <- structure(list(ID = c(1, 2, 3, 5, 4), Gender = c("F", "M", "M", 
"F", "F"), TestDate = structure(c(17897, 17898, 18630, 18262, 
17900), class = "Date"), Test = c("Weight", "Weight", "ELA", 
"ELA", "Math")), row.names = c(NA, -5L), class = c("tbl_df", 
"tbl", "data.frame"))


df2 <- structure(list(Test = c("Weight", "Weight", "ELA", "ELA", "ELA", 
"ELA", "Math", "Math"), Gender = c("F", "M", "F", "M", "F", "M", 
"F", "M"), Date1 = structure(c(17532, 17534, 17536, 17537, 18266, 
18267, 17897, 17539), class = "Date"), Ave = c(97, 99, 85, 84, 
83, 82, 88, 89), Date2 = structure(c(18993, 18995, 18266, 18267, 
18997, 18998, 18999, 19000), class = "Date")), row.names = c(NA, 
-8L), class = c("tbl_df", "tbl", "data.frame"))