primitives: add encoder/decoder types to api.rs

diff --git a/primitives/tests/api.rs b/primitives/tests/api.rs
index 6b6605db..db50201b 100644
--- a/primitives/tests/api.rs
+++ b/primitives/tests/api.rs
@@ -288,11 +288,43 @@ fn api_can_use_all_types_from_module_locktime() {
 #[test]
 fn api_can_use_all_types_from_module_script() {
     use bitcoin_primitives::script::{
-        RedeemScriptSizeError, ScriptHash, ScriptPubKey, ScriptPubKeyBuf, ScriptSig, ScriptSigBuf,
-        WScriptHash, WitnessScriptSizeError,
+        RedeemScriptSizeError, ScriptBufDecoder, ScriptBufDecoderError, ScriptEncoder, ScriptHash,
+        ScriptPubKey, ScriptPubKeyBuf, ScriptSig, ScriptSigBuf, WScriptHash,
+        WitnessScriptSizeError,
     };
 }
 
+#[test]
+fn api_can_use_all_types_from_module_block() {
+    use bitcoin_primitives::block::{
+        BlockDecoder, BlockDecoderError, BlockEncoder, BlockHashDecoder, BlockHashDecoderError,
+        BlockHashEncoder, HeaderDecoder, HeaderEncoder, VersionDecoder, VersionDecoderError,
+        VersionEncoder,
+    };
+}
+
+#[test]
+fn api_can_use_all_types_from_module_merkle_tree() {
+    use bitcoin_primitives::merkle_tree::{
+        TxMerkleNodeDecoder, TxMerkleNodeDecoderError, TxMerkleNodeEncoder,
+    };
+}
+
+#[test]
+fn api_can_use_all_types_from_module_transaction() {
+    use bitcoin_primitives::transaction::{
+        OutPointDecoder, OutPointDecoderError, OutPointEncoder, TransactionDecoder,
+        TransactionDecoderError, TransactionEncoder, TxInDecoder, TxInDecoderError, TxInEncoder,
+        TxOutDecoder, TxOutDecoderError, TxOutEncoder, VersionDecoder, VersionDecoderError,
+        VersionEncoder,
+    };
+}
+
+#[test]
+fn api_can_use_all_types_from_module_witness() {
+    use bitcoin_primitives::witness::{WitnessDecoder, WitnessDecoderError, WitnessEncoder};
+}
+
 // `Debug` representation is never empty (C-DEBUG-NONEMPTY).
 #[test]
 fn api_all_non_error_types_have_non_empty_debug() {