Insert the cells from the `start` position (#15398)
## Summary
The cause of this bug is from
https://github.com/astral-sh/ruff/pull/12575 which was itself a bug fix
but the fix wasn't completely correct.
fixes: #14768
fixes: https://github.com/astral-sh/ruff-vscode/issues/644
## Test Plan
Consider the following three cells:
1.
```python
class Foo:
def __init__(self):
self.x = 1
def __str__(self):
return f"Foo({self.x})"
```
2.
```python
def hello():
print("hello world")
```
3.
```python
y = 1
```
The test case is moving cell 2 to the top i.e., cell 2 goes to position
1 and cell 1 goes to position 2.
Before this fix, it can be seen that the cells were pushed at the end of
the vector:
```
12.643269917s INFO ruff:main ruff_server::edit::notebook: Before update: [
NotebookCell {
document: TextDocument {
contents: "class Foo:\n def __init__(self):\n self.x = 1\n\n def __str__(self):\n return f\"Foo({self.x})\"",
},
},
NotebookCell {
document: TextDocument {
contents: "def hello():\n print(\"hello world\")",
},
},
NotebookCell {
document: TextDocument {
contents: "y = 1",
},
},
]
12.643777667s INFO ruff:main ruff_server::edit::notebook: After update: [
NotebookCell {
document: TextDocument {
contents: "y = 1",
},
},
NotebookCell {
document: TextDocument {
contents: "class Foo:\n def __init__(self):\n self.x = 1\n\n def __str__(self):\n return f\"Foo({self.x})\"",
},
},
NotebookCell {
document: TextDocument {
contents: "def hello():\n print(\"hello world\")",
},
},
]
```
After the fix in this PR, it can be seen that the cells are being pushed
at the correct `start` index:
```
6.520570917s INFO ruff:main ruff_server::edit::notebook: Before update: [
NotebookCell {
document: TextDocument {
contents: "class Foo:\n def __init__(self):\n self.x = 1\n\n def __str__(self):\n return f\"Foo({self.x})\"",
},
},
NotebookCell {
document: TextDocument {
contents: "def hello():\n print(\"hello world\")",
},
},
NotebookCell {
document: TextDocument {
contents: "y = 1",
},
},
]
6.521084792s INFO ruff:main ruff_server::edit::notebook: After update: [
NotebookCell {
document: TextDocument {
contents: "def hello():\n print(\"hello world\")",
},
},
NotebookCell {
document: TextDocument {
contents: "class Foo:\n def __init__(self):\n self.x = 1\n\n def __str__(self):\n return f\"Foo({self.x})\"",
},
},
NotebookCell {
document: TextDocument {
contents: "y = 1",
},
},
]
```
