---
# (DD37) Business Logic — ClinicServiceTests.shouldFindOwnersByLastName() [8 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `org.springframework.samples.petclinic.service.ClinicServiceTests` |
| Layer | Service / Integration Test |
| Module | `service` (Package: `org.springframework.samples.petclinic.service`) |

## 1. Role

### ClinicServiceTests.shouldFindOwnersByLastName()

This test method validates the owner search behavior exposed by the persistence layer through Spring Data JPA. Its business purpose is to confirm that the owner lookup can retrieve all owner records whose last name begins with a supplied prefix, which is the same matching style used by the clinic’s owner search function. The method exercises two representative search outcomes: a positive match for the prefix `Davis`, and a negative match for the non-existent prefix `Daviss`, thereby proving both normal retrieval and empty-result handling.

From a design perspective, the method follows a straightforward arrange-act-assert pattern and acts as a repository integration check rather than a production business service. It does not branch into multiple business categories, but it does validate two result states of the same query path: a populated `Page<Owner>` and an empty `Page<Owner>`. In the wider system, this test protects the owner search feature from regressions by ensuring the repository query contract remains aligned with clinic search expectations.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START["shouldFindOwnersByLastName()"]
    CALL1["ownerRepository.findByLastNameStartingWith(\"Davis\", pageable)"]
    ASSERT1["assertThat(owners).hasSize(2)"]
    CALL2["ownerRepository.findByLastNameStartingWith(\"Daviss\", pageable)"]
    ASSERT2["assertThat(owners).isEmpty()"]
    END_NODE["End"]
    START --> CALL1
    CALL1 --> ASSERT1
    ASSERT1 --> CALL2
    CALL2 --> ASSERT2
    ASSERT2 --> END_NODE
```

**Constant Resolution:**
No external constants are referenced in this method. The only business-relevant literal inputs are the search prefixes `Davis` and `Daviss`.

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| - | (none) | - | - |

This method accepts no parameters. It uses the injected `OwnerRepository` instance and the local `pageable` field (`Pageable.unpaged()`) as external state. The test inputs are the hard-coded last-name prefixes `Davis` and `Daviss`, which determine whether the repository should return matching owners or an empty result set.

## 4. CRUD Operations / Called Services

### Pre-computed evidence from code analysis graph:

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| R | `OwnerRepository.findByLastNameStartingWith` | OwnerRepository | Owner | Calls `findByLastNameStartingWith` in `OwnerRepository` |

Analyze all method calls within this method and classify each as a CRUD operation.
Use the pre-computed evidence above. If SC Code or Entity/DB is missing, try to infer from:
- The **SC Code** (Service Component code, e.g., `EKK0361A010SC`, `EKK1081D010CBS`) — look at the class name of the called method or its containing class.
- The **Entity/DB tables** — search for table name constants (often `KK_T_*` pattern), SQL references, or entity names in the called method's source code.

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| R | `OwnerRepository.findByLastNameStartingWith` | OwnerRepository | Owner | Reads owner records whose last name starts with the supplied prefix |

## 5. Dependency Trace


Trace who calls this method and what this method ultimately calls.
Use the pre-computed evidence and caller search results from Step 2 above.

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | Test runner / JUnit engine | `JUnit Jupiter` -> `ClinicServiceTests.shouldFindOwnersByLastName` | `OwnerRepository.findByLastNameStartingWith [R] Owner` |

**Instructions:**
- Use `search_files` with pattern `**/*.java` and content_pattern `shouldFindOwnersByLastName` to find all callers.
- For each caller, identify if it's a Screen (class name contains `KKSV*`, `Screen*`), Batch, Controller, or CBS.
- Build the full call chain from the entry point to this method.
- Each row = one unique entry point. Show ALL found callers (up to 15 rows).
- The Terminal column lists ALL CRUD endpoints reached FROM this method.
- Format terminal as `methodName [C/R/U/D] EntityOrTableName`
- If a caller class name matches `KKSV\d{4}`, format as `Screen:KKSVxxxx`.

## 6. Per-Branch Detail Blocks

Analyze the method's control flow block by block. Analyze ALL nesting levels — no depth limit.

> Each branch of the control flow is displayed as a hierarchical block structure.

**Block 1** — [SEQUENCE] `(test setup and first repository lookup)` (L88)

> Executes the first search scenario and validates the expected number of matching owners.

| # | Type | Code |
|---|------|------|
| 1 | SET | `Page<Owner> owners = this.owners.findByLastNameStartingWith("Davis", pageable);` |
| 2 | CALL | `this.owners.findByLastNameStartingWith("Davis", pageable);` |
| 3 | EXEC | `assertThat(owners).hasSize(2);` |

**Block 2** — [SEQUENCE] `(second repository lookup and empty-result validation)` (L91)

> Executes the negative search scenario to verify that no owners are returned when the prefix does not exist.

| # | Type | Code |
|---|------|------|
| 1 | SET | `owners = this.owners.findByLastNameStartingWith("Daviss", pageable);` |
| 2 | CALL | `this.owners.findByLastNameStartingWith("Daviss", pageable);` |
| 3 | EXEC | `assertThat(owners).isEmpty();` |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `Owner` | Domain entity | Clinic customer who owns one or more pets |
| `OwnerRepository` | Repository | Persistence component used to query owner records |
| `findByLastNameStartingWith` | Repository query method | Returns owners whose last name begins with the supplied text |
| `Page` | Technical type | Paginated query result wrapper returned by Spring Data |
| `Pageable` | Technical type | Pagination/sorting request descriptor; here it is unpaged |
| `unpaged()` | API method | Requests an unpaginated result set |
| `lastName` | Field | Owner surname used for search and identification |
| `Davis` | Test data value | Existing last-name prefix expected to match two owners |
| `Daviss` | Test data value | Non-matching last-name prefix used to verify empty results |
| JUnit | Test framework | Executes the repository integration test |
| AssertJ | Test assertion library | Verifies result size and emptiness in a fluent style |