pkey_ctx: add dsa params generation test

boring doesn't support DSA paramgen in a pkey ctx since
google/boringssl@2e295b9

Author: huwcbjones

openssl/src/pkey_ctx.rs

@@ -822,6 +822,7 @@ impl<T> PkeyCtxRef<T> {
 
 #[cfg(test)]
 mod test {
+    use cfg_if::cfg_if;
     use super::*;
     #[cfg(not(any(boringssl, awslc)))]
     use crate::cipher::Cipher;
@@ -958,6 +959,28 @@ mod test {
         ctx.keygen().unwrap();
     }
 
+    #[test]
+    #[cfg(not(boringssl))]
+    fn dsa_paramgen() {
+        let mut ctx = PkeyCtx::new_id(Id::DSA).unwrap();
+        ctx.paramgen_init().unwrap();
+        ctx.set_dsa_paramgen_bits(2048).unwrap();
+        let params = ctx.paramgen().unwrap();
+
+        let size = {
+            cfg_if! {
+            if #[cfg(awslc)] {
+                72
+            } else if #[cfg(libressl)] {
+                48
+            } else {
+                64
+            }
+        }
+        };
+        assert_eq!(params.size(), size);
+    }
+
     #[test]
     #[cfg(any(ossl110, boringssl, libressl360, awslc))]
     fn hkdf() {