red_knot_python_semantic: add invalid assignment diagnostic snapshot

This tests the diagnostic rendering of a case that wasn't previously
covered by snapshots: when unpacking fails because there are too few
values, but where the left hand side can tolerate "N or more." In the
code, this is a distinct diagnostic, so we capture it here.

(Sorry about the diff here, but it made sense to rename the other
sections and that changes the name of the snapshot file.)

crates/red_knot_python_semantic/resources/mdtest/diagnostics/unpacking.md

@@ -8,14 +8,20 @@
 a, b = 1  # error: [not-iterable]
 ```
 
-## Too many values to unpack
+## Exactly too many values to unpack
 
 ```py
 a, b = (1, 2, 3)  # error: [invalid-assignment]
 ```
 
-## Too few values to unpack
+## Exactly too few values to unpack
 
 ```py
 a, b = (1,)  # error: [invalid-assignment]
 ```
+
+## Too few values to unpack
+
+```py
+[a, *b, c, d] = (1, 2)  # error: [invalid-assignment]
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/unpacking.md_-_Unpacking_-_Exactly_too_few_values_to_unpack.snap

@@ -0,0 +1,28 @@
+---
+source: crates/red_knot_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: unpacking.md - Unpacking - Exactly too few values to unpack
+mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unpacking.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | a, b = (1,)  # error: [invalid-assignment]
+```
+
+# Diagnostics
+
+```
+error: lint:invalid-assignment
+ --> /src/mdtest_snippet.py:1:1
+  |
+1 | a, b = (1,)  # error: [invalid-assignment]
+  | ^^^^ Not enough values to unpack (expected 2, got 1)
+  |
+
+```

crates/red_knot_python_semantic/resources/mdtest/snapshots/unpacking.md_-_Unpacking_-_Exactly_too_many_values_to_unpack.snap

@@ -3,7 +3,7 @@ source: crates/red_knot_test/src/lib.rs
 expression: snapshot
 ---
 ---
-mdtest name: unpacking.md - Unpacking - Too many values to unpack
+mdtest name: unpacking.md - Unpacking - Exactly too many values to unpack
 mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unpacking.md
 ---
 

crates/red_knot_python_semantic/resources/mdtest/snapshots/unpacking.md_-_Unpacking_-_Too_few_values_to_unpack.snap

@@ -12,7 +12,7 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unpack
 ## mdtest_snippet.py
 
 ```
-1 | a, b = (1,)  # error: [invalid-assignment]
+1 | [a, *b, c, d] = (1, 2)
 ```
 
 # Diagnostics
@@ -21,8 +21,8 @@ mdtest path: crates/red_knot_python_semantic/resources/mdtest/diagnostics/unpack
 error: lint:invalid-assignment
  --> /src/mdtest_snippet.py:1:1
   |
-1 | a, b = (1,)  # error: [invalid-assignment]
-  | ^^^^ Not enough values to unpack (expected 2, got 1)
+1 | [a, *b, c, d] = (1, 2)
+  | ^^^^^^^^^^^^^ Not enough values to unpack (expected 3 or more, got 2)
   |
 
 ```