diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
new file mode 100644
index 0000000..eab63b9
--- /dev/null
+++ b/.github/workflows/rust.yml
@@ -0,0 +1,41 @@
+name: Contracts CI
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+
+jobs:
+  contracts:
+    runs-on: ubuntu-latest
+
+    defaults:
+      run:
+        working-directory: contracts
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+          targets: wasm32-unknown-unknown
+
+      - name: Cache Rust dependencies
+        uses: Swatinem/rust-cache@v2
+
+      - name: Check formatting
+        run: cargo fmt --all -- --check
+
+      - name: Run clippy
+        run: cargo clippy --workspace --all-targets --all-features -- -D warnings
+
+      - name: Run tests
+        run: cargo test --workspace
+
+      - name: Build WASM artifacts
+        run: cargo build --workspace --target wasm32-unknown-unknown --release
+
diff --git a/contracts/Cargo.toml b/contracts/Cargo.toml
index 6576b9a..8803414 100644
--- a/contracts/Cargo.toml
+++ b/contracts/Cargo.toml
@@ -1,13 +1,3 @@
-[package]
-name = "geev-core"
-version = "0.1.0"
-edition = "2021"
-
-[lib]
-crate-type = ["cdylib"]
-
-[dependencies]
-soroban-sdk = "25.0.0"
-
-[dev-dependencies]
-soroban-sdk = { version = "25.0.0", features = ["testutils"] }
\ No newline at end of file
+[workspace]
+members = ["geev-core"]
+resolver = "2"
diff --git a/contracts/geev-core/Cargo.toml b/contracts/geev-core/Cargo.toml
index feb04fa..4639c9f 100644
--- a/contracts/geev-core/Cargo.toml
+++ b/contracts/geev-core/Cargo.toml
@@ -4,4 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+soroban-sdk = { version = "22.0.0", default-features = false }
+
+[dev-dependencies]
 soroban-sdk = { version = "22.0.0", features = ["testutils"] }
diff --git a/contracts/geev-core/src/giveaway.rs b/contracts/geev-core/src/giveaway.rs
index 85176e8..e9c05de 100644
--- a/contracts/geev-core/src/giveaway.rs
+++ b/contracts/geev-core/src/giveaway.rs
@@ -1,20 +1,8 @@
-use soroban_sdk::{contracttype, Address, Env, Symbol, token};
+use soroban_sdk::{contracttype, Address, Env};
 
 #[derive(Clone, Copy, PartialEq, Eq)]
 #[contracttype]
-pub enum GiveawayStatus {
-    Active,
-    Ended,
-}
-
-#[derive(Clone)]
-#[contracttype]
 pub struct Giveaway {
-    pub id: u64,
-    pub status: GiveawayStatus,
-    pub creator: Address,
-    pub token: Address,
-    pub amount: i128,
     pub end_time: u64,
     pub participant_count: u32,
 }
@@ -24,52 +12,15 @@ pub struct Giveaway {
 pub enum DataKey {
     Giveaway(u64),
     Participant(u64, Address),
-    GiveawayCount,
 }
 
-pub fn create_giveaway(
-    env: Env,
-    creator: Address,
-    token: Address,
-    amount: i128,
-    end_time: u64,
-) -> u64 {
-    creator.require_auth();
-
-    // Initialize the Token Client using the provided token address
-    let token_client = token::Client::new(&env, &token);
-
-    // Execute transfer from creator to current contract
-    token_client.transfer(&creator, &env.current_contract_address(), &amount);
-
-    // Generate a new Giveaway ID
-    let count_key = DataKey::GiveawayCount;
-    let mut count: u64 = env.storage().instance().get(&count_key).unwrap_or(0);
-    count += 1;
-    env.storage().instance().set(&count_key, &count);
-
-    // Create Giveaway struct
+pub fn create_giveaway(env: &Env, giveaway_id: u64, end_time: u64) {
+    let key = DataKey::Giveaway(giveaway_id);
     let giveaway = Giveaway {
-        id: count,
-        status: GiveawayStatus::Active,
-        creator: creator.clone(),
-        token: token.clone(),
-        amount,
         end_time,
         participant_count: 0,
     };
-
-    // Save struct to Persistent Storage under key: Giveaway(id)
-    let giveaway_key = DataKey::Giveaway(count);
-    env.storage().persistent().set(&giveaway_key, &giveaway);
-
-    // Emit GiveawayCreated event for the NestJS indexer
-    env.events().publish(
-        (Symbol::new(&env, "GiveawayCreated"), count, creator),
-        (amount, token),
-    );
-
-    count
+    env.storage().persistent().set(&key, &giveaway);
 }
 
 pub fn enter_giveaway(env: Env, user: Address, giveaway_id: u64) {
@@ -88,13 +39,12 @@ pub fn enter_giveaway(env: Env, user: Address, giveaway_id: u64) {
     }
 
     let participant_key = DataKey::Participant(giveaway_id, user.clone());
-    if env.storage().instance().has(&participant_key) {
+    if env.storage().persistent().has(&participant_key) {
         panic!("Double Entry");
     }
 
-    env.storage().instance().set(&participant_key, &true);
+    env.storage().persistent().set(&participant_key, &true);
 
     giveaway.participant_count += 1;
     env.storage().persistent().set(&giveaway_key, &giveaway);
 }
-
diff --git a/contracts/geev-core/src/lib.rs b/contracts/geev-core/src/lib.rs
index 79f518f..125b1b7 100644
--- a/contracts/geev-core/src/lib.rs
+++ b/contracts/geev-core/src/lib.rs
@@ -1,4 +1,5 @@
-mod giveaway;
+#![no_std]
 
-pub use giveaway::{enter_giveaway, DataKey, Giveaway};
+mod giveaway;
 
+pub use giveaway::{create_giveaway, enter_giveaway, DataKey, Giveaway};
diff --git a/contracts/geev-core/test_snapshots/enter_once_before_end_increments_participant_count.1.json b/contracts/geev-core/test_snapshots/enter_once_before_end_increments_participant_count.1.json
new file mode 100644
index 0000000..4189780
--- /dev/null
+++ b/contracts/geev-core/test_snapshots/enter_once_before_end_increments_participant_count.1.json
@@ -0,0 +1,236 @@
+{
+  "generators": {
+    "address": 2,
+    "nonce": 0
+  },
+  "auth": [
+    [],
+    [
+      [
+        "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+        {
+          "function": {
+            "contract_fn": {
+              "contract_address": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+              "function_name": "",
+              "args": []
+            }
+          },
+          "sub_invocations": []
+        }
+      ]
+    ]
+  ],
+  "ledger": {
+    "protocol_version": 22,
+    "sequence_number": 0,
+    "timestamp": 10,
+    "network_id": "0000000000000000000000000000000000000000000000000000000000000000",
+    "base_reserve": 0,
+    "min_persistent_entry_ttl": 4096,
+    "min_temp_entry_ttl": 16,
+    "max_entry_ttl": 6312000,
+    "ledger_entries": [
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+            "key": {
+              "ledger_key_nonce": {
+                "nonce": 801925984706572462
+              }
+            },
+            "durability": "temporary"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+                "key": {
+                  "ledger_key_nonce": {
+                    "nonce": 801925984706572462
+                  }
+                },
+                "durability": "temporary",
+                "val": "void"
+              }
+            },
+            "ext": "v0"
+          },
+          6311999
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": {
+              "vec": [
+                {
+                  "symbol": "Giveaway"
+                },
+                {
+                  "u64": 1
+                }
+              ]
+            },
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": {
+                  "vec": [
+                    {
+                      "symbol": "Giveaway"
+                    },
+                    {
+                      "u64": 1
+                    }
+                  ]
+                },
+                "durability": "persistent",
+                "val": {
+                  "map": [
+                    {
+                      "key": {
+                        "symbol": "end_time"
+                      },
+                      "val": {
+                        "u64": 20
+                      }
+                    },
+                    {
+                      "key": {
+                        "symbol": "participant_count"
+                      },
+                      "val": {
+                        "u32": 1
+                      }
+                    }
+                  ]
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": {
+              "vec": [
+                {
+                  "symbol": "Participant"
+                },
+                {
+                  "u64": 1
+                },
+                {
+                  "address": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM"
+                }
+              ]
+            },
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": {
+                  "vec": [
+                    {
+                      "symbol": "Participant"
+                    },
+                    {
+                      "u64": 1
+                    },
+                    {
+                      "address": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM"
+                    }
+                  ]
+                },
+                "durability": "persistent",
+                "val": {
+                  "bool": true
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": "ledger_key_contract_instance",
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": "ledger_key_contract_instance",
+                "durability": "persistent",
+                "val": {
+                  "contract_instance": {
+                    "executable": {
+                      "wasm": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+                    },
+                    "storage": null
+                  }
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_code": {
+            "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_code": {
+                "ext": "v0",
+                "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+                "code": ""
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ]
+    ]
+  },
+  "events": []
+}
\ No newline at end of file
diff --git a/contracts/geev-core/test_snapshots/reject_duplicate_entries.1.json b/contracts/geev-core/test_snapshots/reject_duplicate_entries.1.json
new file mode 100644
index 0000000..fa5add3
--- /dev/null
+++ b/contracts/geev-core/test_snapshots/reject_duplicate_entries.1.json
@@ -0,0 +1,221 @@
+{
+  "generators": {
+    "address": 2,
+    "nonce": 0
+  },
+  "auth": [
+    []
+  ],
+  "ledger": {
+    "protocol_version": 22,
+    "sequence_number": 0,
+    "timestamp": 10,
+    "network_id": "0000000000000000000000000000000000000000000000000000000000000000",
+    "base_reserve": 0,
+    "min_persistent_entry_ttl": 4096,
+    "min_temp_entry_ttl": 16,
+    "max_entry_ttl": 6312000,
+    "ledger_entries": [
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+            "key": {
+              "ledger_key_nonce": {
+                "nonce": 801925984706572462
+              }
+            },
+            "durability": "temporary"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+                "key": {
+                  "ledger_key_nonce": {
+                    "nonce": 801925984706572462
+                  }
+                },
+                "durability": "temporary",
+                "val": "void"
+              }
+            },
+            "ext": "v0"
+          },
+          6311999
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": {
+              "vec": [
+                {
+                  "symbol": "Giveaway"
+                },
+                {
+                  "u64": 3
+                }
+              ]
+            },
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": {
+                  "vec": [
+                    {
+                      "symbol": "Giveaway"
+                    },
+                    {
+                      "u64": 3
+                    }
+                  ]
+                },
+                "durability": "persistent",
+                "val": {
+                  "map": [
+                    {
+                      "key": {
+                        "symbol": "end_time"
+                      },
+                      "val": {
+                        "u64": 20
+                      }
+                    },
+                    {
+                      "key": {
+                        "symbol": "participant_count"
+                      },
+                      "val": {
+                        "u32": 1
+                      }
+                    }
+                  ]
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": {
+              "vec": [
+                {
+                  "symbol": "Participant"
+                },
+                {
+                  "u64": 3
+                },
+                {
+                  "address": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM"
+                }
+              ]
+            },
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": {
+                  "vec": [
+                    {
+                      "symbol": "Participant"
+                    },
+                    {
+                      "u64": 3
+                    },
+                    {
+                      "address": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM"
+                    }
+                  ]
+                },
+                "durability": "persistent",
+                "val": {
+                  "bool": true
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": "ledger_key_contract_instance",
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": "ledger_key_contract_instance",
+                "durability": "persistent",
+                "val": {
+                  "contract_instance": {
+                    "executable": {
+                      "wasm": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+                    },
+                    "storage": null
+                  }
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_code": {
+            "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_code": {
+                "ext": "v0",
+                "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+                "code": ""
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ]
+    ]
+  },
+  "events": []
+}
\ No newline at end of file
diff --git a/contracts/geev-core/test_snapshots/reject_entry_after_end_time.1.json b/contracts/geev-core/test_snapshots/reject_entry_after_end_time.1.json
new file mode 100644
index 0000000..c37721b
--- /dev/null
+++ b/contracts/geev-core/test_snapshots/reject_entry_after_end_time.1.json
@@ -0,0 +1,170 @@
+{
+  "generators": {
+    "address": 2,
+    "nonce": 0
+  },
+  "auth": [
+    []
+  ],
+  "ledger": {
+    "protocol_version": 22,
+    "sequence_number": 0,
+    "timestamp": 10,
+    "network_id": "0000000000000000000000000000000000000000000000000000000000000000",
+    "base_reserve": 0,
+    "min_persistent_entry_ttl": 4096,
+    "min_temp_entry_ttl": 16,
+    "max_entry_ttl": 6312000,
+    "ledger_entries": [
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+            "key": {
+              "ledger_key_nonce": {
+                "nonce": 801925984706572462
+              }
+            },
+            "durability": "temporary"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+                "key": {
+                  "ledger_key_nonce": {
+                    "nonce": 801925984706572462
+                  }
+                },
+                "durability": "temporary",
+                "val": "void"
+              }
+            },
+            "ext": "v0"
+          },
+          6311999
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": {
+              "vec": [
+                {
+                  "symbol": "Giveaway"
+                },
+                {
+                  "u64": 2
+                }
+              ]
+            },
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": {
+                  "vec": [
+                    {
+                      "symbol": "Giveaway"
+                    },
+                    {
+                      "u64": 2
+                    }
+                  ]
+                },
+                "durability": "persistent",
+                "val": {
+                  "map": [
+                    {
+                      "key": {
+                        "symbol": "end_time"
+                      },
+                      "val": {
+                        "u64": 5
+                      }
+                    },
+                    {
+                      "key": {
+                        "symbol": "participant_count"
+                      },
+                      "val": {
+                        "u32": 0
+                      }
+                    }
+                  ]
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+            "key": "ledger_key_contract_instance",
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFCT4",
+                "key": "ledger_key_contract_instance",
+                "durability": "persistent",
+                "val": {
+                  "contract_instance": {
+                    "executable": {
+                      "wasm": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+                    },
+                    "storage": null
+                  }
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_code": {
+            "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_code": {
+                "ext": "v0",
+                "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+                "code": ""
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ]
+    ]
+  },
+  "events": []
+}
\ No newline at end of file
diff --git a/contracts/geev-core/tests/enter_giveaway.rs b/contracts/geev-core/tests/enter_giveaway.rs
index 26d31ad..69b68f2 100644
--- a/contracts/geev-core/tests/enter_giveaway.rs
+++ b/contracts/geev-core/tests/enter_giveaway.rs
@@ -1,25 +1,30 @@
-use soroban_sdk::{testutils::{Address as AddressTest, Ledger}, Address, Env};
-use geev_core::{enter_giveaway, DataKey, Giveaway};
+use geev_core::{create_giveaway, enter_giveaway};
+use soroban_sdk::{
+    contract, contractimpl,
+    testutils::{Address as AddressTest, Ledger},
+    Address, Env,
+};
+
+#[contract]
+pub struct TestContract;
+
+#[contractimpl]
+impl TestContract {
+    pub fn dummy(_env: Env) {}
+}
 
 #[test]
 fn enter_once_before_end_increments_participant_count() {
     let env = Env::default();
+    env.mock_all_auths();
     env.ledger().set_timestamp(10);
     let user = <Address as AddressTest>::generate(&env);
 
     let giveaway_id: u64 = 1;
-    let contract_id = <Address as AddressTest>::generate(&env);
+    let contract_id = env.register(TestContract, ());
 
     env.as_contract(&contract_id, || {
-        let key = DataKey::Giveaway(giveaway_id);
-
-        let giveaway = Giveaway {
-            end_time: 20,
-            participant_count: 0,
-        };
-
-        env.storage().instance().set(&key, &giveaway);
-
+        create_giveaway(&env, giveaway_id, 20);
         enter_giveaway(env.clone(), user.clone(), giveaway_id);
     });
 }
@@ -28,22 +33,15 @@ fn enter_once_before_end_increments_participant_count() {
 #[should_panic]
 fn reject_entry_after_end_time() {
     let env = Env::default();
+    env.mock_all_auths();
     env.ledger().set_timestamp(10);
     let user = <Address as AddressTest>::generate(&env);
 
     let giveaway_id: u64 = 2;
-    let contract_id = <Address as AddressTest>::generate(&env);
+    let contract_id = env.register(TestContract, ());
 
     env.as_contract(&contract_id, || {
-        let key = DataKey::Giveaway(giveaway_id);
-
-        let giveaway = Giveaway {
-            end_time: 5, // already ended relative to timestamp 10
-            participant_count: 0,
-        };
-
-        env.storage().instance().set(&key, &giveaway);
-
+        create_giveaway(&env, giveaway_id, 5);
         enter_giveaway(env.clone(), user.clone(), giveaway_id);
     });
 }
@@ -52,22 +50,15 @@ fn reject_entry_after_end_time() {
 #[should_panic]
 fn reject_duplicate_entries() {
     let env = Env::default();
+    env.mock_all_auths();
     env.ledger().set_timestamp(10);
     let user = <Address as AddressTest>::generate(&env);
 
     let giveaway_id: u64 = 3;
-    let contract_id = <Address as AddressTest>::generate(&env);
+    let contract_id = env.register(TestContract, ());
 
     env.as_contract(&contract_id, || {
-        let key = DataKey::Giveaway(giveaway_id);
-
-        let giveaway = Giveaway {
-            end_time: 20,
-            participant_count: 0,
-        };
-
-        env.storage().instance().set(&key, &giveaway);
-
+        create_giveaway(&env, giveaway_id, 20);
         enter_giveaway(env.clone(), user.clone(), giveaway_id);
 
         // second attempt should fail due to duplicate entry