Add and move tests to kill mutants

diff --git a/.cargo/mutants.toml b/.cargo/mutants.toml
index 7006c602..29ac6b3b 100644
--- a/.cargo/mutants.toml
+++ b/.cargo/mutants.toml
@@ -70,6 +70,7 @@ exclude_re = [
     "primitives/.* calculate_root_batched", # Behind cfg(target_arch = "aarch64"), not compiled on x86_64 CI runner
     "primitives/.* <impl MerkleNode for TxMerkleNode>::calculate_root", # Behind cfg(target_arch = "aarch64"), not compiled on x86_64 CI runner
     "primitives/.* <impl MerkleNode for WitnessMerkleNode>::calculate_root", # Behind cfg(target_arch = "aarch64"), not compiled on x86_64 CI runner
+    "primitives/.* replace \\% with \\+ in ScriptBuf<T>::push_slice_no_opt", # as u8 truncation makes >= 0x100 impossible to test
 
     # consensus_encoding - most of these are for mutations in the logic used to determine when to stop encoding or decoding.
     "consensus_encoding/.* <impl Decoder for ArrayDecoder<N>>::push_bytes", # Mutations cause an infinite loop
diff --git a/bitcoin/src/blockdata/script/tests.rs b/bitcoin/src/blockdata/script/tests.rs
index abbe0671..02748176 100644
--- a/bitcoin/src/blockdata/script/tests.rs
+++ b/bitcoin/src/blockdata/script/tests.rs
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: CC0-1.0
 
-#[cfg(feature = "serde")]
-use alloc::borrow::ToOwned;
 use alloc::string::ToString;
 
 use hex::hex;
@@ -267,22 +265,6 @@ fn script_x_only_key() {
     assert_eq!(script.into_bytes(), &hex!(KEYSTR) as &[u8]);
 }
 
-#[test]
-fn script_builder() {
-    // from txid 3bb5e6434c11fb93f64574af5d116736510717f2c595eb45b52c28e31622dfff which was in my mempool when I wrote the test
-    let script = ScriptPubKey::builder()
-        .push_opcode(OP_DUP)
-        .push_opcode(OP_HASH160)
-        .push_slice(hex!("16e1ae70ff0fa102905d4af297f6912bda6cce19"))
-        .push_opcode(OP_EQUALVERIFY)
-        .push_opcode(OP_CHECKSIG)
-        .into_script();
-    assert_eq!(
-        script.to_hex_string_no_length_prefix(),
-        "76a91416e1ae70ff0fa102905d4af297f6912bda6cce1988ac"
-    );
-}
-
 #[test]
 fn script_builder_with_capacity() {
     let script = Builder::<Tag>::with_capacity(42);
@@ -587,55 +569,6 @@ fn multisig() {
     .is_multisig());
 }
 
-#[test]
-#[cfg(feature = "serde")]
-fn script_json_serialize() {
-    use serde_json;
-
-    let original = ScriptBuf::from_hex_no_length_prefix("827651a0698faaa9a8a7a687").unwrap();
-    let json = serde_json::to_value(&original).unwrap();
-    assert_eq!(json, serde_json::Value::String("827651a0698faaa9a8a7a687".to_owned()));
-    let des = serde_json::from_value::<ScriptBuf>(json).unwrap();
-    assert_eq!(original, des);
-}
-
-#[test]
-fn script_asm() {
-    assert_eq!(
-        ScriptBuf::from_hex_no_length_prefix("6363636363686868686800").unwrap().to_string(),
-        "OP_IF OP_IF OP_IF OP_IF OP_IF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_0"
-    );
-    assert_eq!(ScriptBuf::from_hex_no_length_prefix("2102715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699ac").unwrap().to_string(),
-               "OP_PUSHBYTES_33 02715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699 OP_CHECKSIG");
-    // Elements Alpha peg-out transaction with some signatures removed for brevity. Mainly to test PUSHDATA1
-    assert_eq!(ScriptBuf::from_hex_no_length_prefix("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").unwrap().to_string(),
-               "OP_0 OP_PUSHBYTES_71 304402202457e78cc1b7f50d0543863c27de75d07982bde8359b9e3316adec0aec165f2f02200203fd331c4e4a4a02f48cf1c291e2c0d6b2f7078a784b5b3649fca41f8794d401 OP_0 OP_PUSHDATA1 552103244e602b46755f24327142a0517288cebd159eccb6ccf41ea6edf1f601e9af952103bbbacc302d19d29dbfa62d23f37944ae19853cf260c745c2bea739c95328fcb721039227e83246bd51140fe93538b2301c9048be82ef2fb3c7fc5d78426ed6f609ad210229bf310c379b90033e2ecb07f77ecf9b8d59acb623ab7be25a0caed539e2e6472103703e2ed676936f10b3ce9149fa2d4a32060fb86fa9a70a4efe3f21d7ab90611921031e9b7c6022400a6bb0424bbcde14cff6c016b91ee3803926f3440abf5c146d05210334667f975f55a8455d515a2ef1c94fdfa3315f12319a14515d2a13d82831f62f57ae");
-    // Various weird scripts found in transaction 6d7ed9914625c73c0288694a6819196a27ef6c08f98e1270d975a8e65a3dc09a
-    // which triggered overflow bugs on 32-bit machines in script formatting in the past.
-    assert_eq!(
-        ScriptBuf::from_hex_no_length_prefix("01").unwrap().to_string(),
-        "OP_PUSHBYTES_1 <push past end>"
-    );
-    assert_eq!(
-        ScriptBuf::from_hex_no_length_prefix("0201").unwrap().to_string(),
-        "OP_PUSHBYTES_2 <push past end>"
-    );
-    assert_eq!(ScriptBuf::from_hex_no_length_prefix("4c").unwrap().to_string(), "<unexpected end>");
-    assert_eq!(
-        ScriptBuf::from_hex_no_length_prefix("4c0201").unwrap().to_string(),
-        "OP_PUSHDATA1 <push past end>"
-    );
-    assert_eq!(ScriptBuf::from_hex_no_length_prefix("4d").unwrap().to_string(), "<unexpected end>");
-    assert_eq!(
-        ScriptBuf::from_hex_no_length_prefix("4dffff01").unwrap().to_string(),
-        "OP_PUSHDATA2 <push past end>"
-    );
-    assert_eq!(
-        ScriptBuf::from_hex_no_length_prefix("4effffffff01").unwrap().to_string(),
-        "OP_PUSHDATA4 <push past end>"
-    );
-}
-
 #[test]
 fn script_buf_collect() {
     assert_eq!(&core::iter::empty::<Instruction<'_>>().collect::<ScriptBuf>(), Script::new());
diff --git a/primitives/src/script/builder.rs b/primitives/src/script/builder.rs
index f903a2e5..b0cc69f3 100644
--- a/primitives/src/script/builder.rs
+++ b/primitives/src/script/builder.rs
@@ -81,3 +81,113 @@ impl<T> fmt::Display for Builder<T> {
 impl<T> fmt::Debug for Builder<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(self, f) }
 }
+
+#[cfg(test)]
+mod tests {
+    use alloc::{format, vec};
+
+    use super::Builder;
+    use crate::script::{PushBytes, ScriptSigTag as Tag};
+
+    #[test]
+    fn push_slice_minimal() {
+        let script = Builder::<Tag>::new().push_slice([0x81]).into_script();
+        assert_eq!(script.as_bytes(), &[0x4f]);
+
+        for n in 1u8..=16 {
+            let script = Builder::<Tag>::new().push_slice([n]).into_script();
+            assert_eq!(script.as_bytes(), &[0x50 + n]);
+        }
+
+        let script = Builder::<Tag>::new().push_slice([0u8]).into_script();
+        assert_eq!(script.as_bytes(), &[1, 0]);
+        let script = Builder::<Tag>::new().push_slice([17u8]).into_script();
+        assert_eq!(script.as_bytes(), &[1, 17]);
+        let script = Builder::<Tag>::new().push_slice(b"NRA4VR").into_script();
+        assert_eq!(script.as_bytes(), &[6, b'N', b'R', b'A', b'4', b'V', b'R']);
+    }
+
+    #[test]
+    fn push_slice_non_minimal() {
+        let script = Builder::<Tag>::new().push_slice_non_minimal([0x81]).into_script();
+        assert_eq!(script.as_bytes(), &[1, 0x81]);
+
+        let script = Builder::<Tag>::new().push_slice_non_minimal([1u8]).into_script();
+        assert_eq!(script.as_bytes(), &[1, 1]);
+    }
+
+    #[test]
+    fn push_slice_pushdata1_and_pushdata2() {
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from([0xab; 0x4b].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(script.as_bytes()[0], 0x4b);
+        assert_eq!(script.len(), 1 + 0x4b);
+
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from([0xab; 0x4c].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..2], &[0x4c, 0x4c]);
+        assert_eq!(script.len(), 2 + 0x4c);
+
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from([0xab; 0xff].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..2], &[0x4c, 0xff]);
+        assert_eq!(script.len(), 2 + 0xff);
+
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from([0xab; 0x100].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..3], &[0x4d, 0x00, 0x01]);
+        assert_eq!(script.len(), 3 + 0x100);
+
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from([0xab; 0x102].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..3], &[0x4d, 0x02, 0x01]);
+        assert_eq!(script.len(), 3 + 0x102);
+
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from(vec![0xab; 0xffff].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..3], &[0x4d, 0xff, 0xff]);
+        assert_eq!(script.len(), 3 + 0xffff);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn push_slice_pushdata4_boundary() {
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from(vec![0u8; 0x10000].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..5], &[0x4e, 0x00, 0x00, 0x01, 0x00]);
+        assert_eq!(script.len(), 5 + 0x10000);
+    }
+
+    #[test]
+    #[cfg(target_pointer_width = "64")]
+    #[cfg_attr(miri, ignore)]
+    fn push_slice_pushdata4_length_bytes() {
+        let len = 0x0102_0304;
+        let script = Builder::<Tag>::new()
+            .push_slice(<&PushBytes>::try_from(vec![0u8; len].as_slice()).unwrap())
+            .into_script();
+        assert_eq!(&script.as_bytes()[..5], &[0x4e, 0x04, 0x03, 0x02, 0x01]);
+        assert_eq!(script.len(), 5 + len);
+    }
+
+    #[test]
+    fn from_vec() {
+        let script = Builder::<Tag>::from(vec![0xac, 0x51]).into_script();
+        assert_eq!(script.as_bytes(), &[0xac, 0x51]);
+    }
+
+    #[test]
+    fn display_delegates_to_script() {
+        let builder = Builder::<Tag>::from(vec![0x51, 0x52]);
+        let displayed = format!("{}", builder);
+        assert!(!displayed.is_empty());
+        assert_eq!(displayed, format!("{}", builder.as_script()));
+    }
+}
diff --git a/primitives/src/script/owned.rs b/primitives/src/script/owned.rs
index 81e51883..562a77d6 100644
--- a/primitives/src/script/owned.rs
+++ b/primitives/src/script/owned.rs
@@ -342,3 +342,34 @@ impl<'a, T> Arbitrary<'a> for ScriptBuf<T> {
         Ok(Self::from_bytes(v))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use alloc::vec;
+
+    use super::ScriptBuf;
+    use crate::script::ScriptSigTag as Tag;
+
+    #[test]
+    fn reserved_len_for_slice() {
+        // Length plus the size of the push opcode that prefixes it.
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0), 1);
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0x4b), 0x4b + 1);
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0x4c), 0x4c + 2);
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0xff), 0xff + 2);
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0x100), 0x100 + 3);
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0xffff), 0xffff + 3);
+        assert_eq!(ScriptBuf::<Tag>::reserved_len_for_slice(0x10000), 0x10000 + 5);
+    }
+
+    #[test]
+    fn as_byte_vec_deref_restores() {
+        let mut script = ScriptBuf::<Tag>::from_bytes(vec![1, 2, 3]);
+        {
+            let vec = script.as_byte_vec();
+            assert_eq!(vec.len(), 3);
+            assert_eq!(vec.as_slice(), &[1, 2, 3]);
+        }
+        assert_eq!(script.as_bytes(), &[1, 2, 3]);
+    }
+}
diff --git a/primitives/src/script/tests.rs b/primitives/src/script/tests.rs
index f5b4286d..bfd74296 100644
--- a/primitives/src/script/tests.rs
+++ b/primitives/src/script/tests.rs
@@ -186,6 +186,78 @@ fn script_is_empty() {
     assert!(!script.is_empty());
 }
 
+#[test]
+#[cfg(feature = "hex")]
+fn script_builder() {
+    use hex::hex;
+
+    use crate::opcodes::all::{OP_CHECKSIG, OP_DUP, OP_EQUALVERIFY, OP_HASH160};
+
+    // from txid 3bb5e6434c11fb93f64574af5d116736510717f2c595eb45b52c28e31622dfff which was in my mempool when I wrote the test
+    let script = Builder::<ScriptPubKeyTag>::new()
+        .push_opcode(OP_DUP)
+        .push_opcode(OP_HASH160)
+        .push_slice(hex!("16e1ae70ff0fa102905d4af297f6912bda6cce19"))
+        .push_opcode(OP_EQUALVERIFY)
+        .push_opcode(OP_CHECKSIG)
+        .into_script();
+    assert_eq!(
+        script.to_hex_string_no_length_prefix(),
+        "76a91416e1ae70ff0fa102905d4af297f6912bda6cce1988ac"
+    );
+}
+
+#[test]
+#[cfg(feature = "hex")]
+#[cfg(feature = "serde")]
+fn script_json_serialize() {
+    use serde_json;
+
+    let original = ScriptBuf::from_hex_no_length_prefix("827651a0698faaa9a8a7a687").unwrap();
+    let json = serde_json::to_value(&original).unwrap();
+    assert_eq!(json, serde_json::Value::String("827651a0698faaa9a8a7a687".to_owned()));
+    let des = serde_json::from_value::<ScriptBuf>(json).unwrap();
+    assert_eq!(original, des);
+}
+
+#[test]
+#[cfg(feature = "hex")]
+fn script_asm() {
+    assert_eq!(
+        ScriptBuf::from_hex_no_length_prefix("6363636363686868686800").unwrap().to_string(),
+        "OP_IF OP_IF OP_IF OP_IF OP_IF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_0"
+    );
+    assert_eq!(ScriptBuf::from_hex_no_length_prefix("2102715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699ac").unwrap().to_string(),
+               "OP_PUSHBYTES_33 02715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699 OP_CHECKSIG");
+    // Elements Alpha peg-out transaction with some signatures removed for brevity. Mainly to test PUSHDATA1
+    assert_eq!(ScriptBuf::from_hex_no_length_prefix("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").unwrap().to_string(),
+               "OP_0 OP_PUSHBYTES_71 304402202457e78cc1b7f50d0543863c27de75d07982bde8359b9e3316adec0aec165f2f02200203fd331c4e4a4a02f48cf1c291e2c0d6b2f7078a784b5b3649fca41f8794d401 OP_0 OP_PUSHDATA1 552103244e602b46755f24327142a0517288cebd159eccb6ccf41ea6edf1f601e9af952103bbbacc302d19d29dbfa62d23f37944ae19853cf260c745c2bea739c95328fcb721039227e83246bd51140fe93538b2301c9048be82ef2fb3c7fc5d78426ed6f609ad210229bf310c379b90033e2ecb07f77ecf9b8d59acb623ab7be25a0caed539e2e6472103703e2ed676936f10b3ce9149fa2d4a32060fb86fa9a70a4efe3f21d7ab90611921031e9b7c6022400a6bb0424bbcde14cff6c016b91ee3803926f3440abf5c146d05210334667f975f55a8455d515a2ef1c94fdfa3315f12319a14515d2a13d82831f62f57ae");
+    // Various weird scripts found in transaction 6d7ed9914625c73c0288694a6819196a27ef6c08f98e1270d975a8e65a3dc09a
+    // which triggered overflow bugs on 32-bit machines in script formatting in the past.
+    assert_eq!(
+        ScriptBuf::from_hex_no_length_prefix("01").unwrap().to_string(),
+        "OP_PUSHBYTES_1 <push past end>"
+    );
+    assert_eq!(
+        ScriptBuf::from_hex_no_length_prefix("0201").unwrap().to_string(),
+        "OP_PUSHBYTES_2 <push past end>"
+    );
+    assert_eq!(ScriptBuf::from_hex_no_length_prefix("4c").unwrap().to_string(), "<unexpected end>");
+    assert_eq!(
+        ScriptBuf::from_hex_no_length_prefix("4c0201").unwrap().to_string(),
+        "OP_PUSHDATA1 <push past end>"
+    );
+    assert_eq!(ScriptBuf::from_hex_no_length_prefix("4d").unwrap().to_string(), "<unexpected end>");
+    assert_eq!(
+        ScriptBuf::from_hex_no_length_prefix("4dffff01").unwrap().to_string(),
+        "OP_PUSHDATA2 <push past end>"
+    );
+    assert_eq!(
+        ScriptBuf::from_hex_no_length_prefix("4effffffff01").unwrap().to_string(),
+        "OP_PUSHDATA4 <push past end>"
+    );
+}
+
 #[test]
 fn test_index() {
     let script = Script::from_bytes(&[1, 2, 3, 4, 5]);