diff --git a/toolchain/check/testdata/expression_category/in_place_tuple_init.carbon b/toolchain/check/testdata/expr_category/in_place_tuple_init.carbon
similarity index 100%
rename from toolchain/check/testdata/expression_category/in_place_tuple_init.carbon
rename to toolchain/check/testdata/expr_category/in_place_tuple_init.carbon
diff --git a/toolchain/check/testdata/if_expression/basic.carbon b/toolchain/check/testdata/if_expr/basic.carbon
similarity index 100%
rename from toolchain/check/testdata/if_expression/basic.carbon
rename to toolchain/check/testdata/if_expr/basic.carbon
diff --git a/toolchain/check/testdata/if_expression/constant_condition.carbon b/toolchain/check/testdata/if_expr/constant_condition.carbon
similarity index 100%
rename from toolchain/check/testdata/if_expression/constant_condition.carbon
rename to toolchain/check/testdata/if_expr/constant_condition.carbon
diff --git a/toolchain/check/testdata/if_expression/control_flow.carbon b/toolchain/check/testdata/if_expr/control_flow.carbon
similarity index 100%
rename from toolchain/check/testdata/if_expression/control_flow.carbon
rename to toolchain/check/testdata/if_expr/control_flow.carbon
diff --git a/toolchain/check/testdata/if_expression/fail_not_in_function.carbon b/toolchain/check/testdata/if_expr/fail_not_in_function.carbon
similarity index 100%
rename from toolchain/check/testdata/if_expression/fail_not_in_function.carbon
rename to toolchain/check/testdata/if_expr/fail_not_in_function.carbon
diff --git a/toolchain/check/testdata/if_expression/nested.carbon b/toolchain/check/testdata/if_expr/nested.carbon
similarity index 100%
rename from toolchain/check/testdata/if_expression/nested.carbon
rename to toolchain/check/testdata/if_expr/nested.carbon
diff --git a/toolchain/check/testdata/if_expression/struct.carbon b/toolchain/check/testdata/if_expr/struct.carbon
similarity index 100%
rename from toolchain/check/testdata/if_expression/struct.carbon
rename to toolchain/check/testdata/if_expr/struct.carbon
diff --git a/toolchain/check/testdata/index/expression_category.carbon b/toolchain/check/testdata/index/expr_category.carbon
similarity index 99%
rename from toolchain/check/testdata/index/expression_category.carbon
rename to toolchain/check/testdata/index/expr_category.carbon
index e47cb67369e1..4af9a4cff645 100644
--- a/toolchain/check/testdata/index/expression_category.carbon
+++ b/toolchain/check/testdata/index/expr_category.carbon
@@ -29,7 +29,7 @@ fn ValueBinding(b: [i32; 3]) {
 // CHECK:STDOUT:   %.loc10: type = tuple_type (i32, i32, i32)
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: file "expression_category.carbon" {
+// CHECK:STDOUT: file "expr_category.carbon" {
 // CHECK:STDOUT:   %F: <function> = fn_decl @F
 // CHECK:STDOUT:   %G: <function> = fn_decl @G
 // CHECK:STDOUT:   %ValueBinding: <function> = fn_decl @ValueBinding
diff --git a/toolchain/check/testdata/index/fail_expression_category.carbon b/toolchain/check/testdata/index/fail_expr_category.carbon
similarity index 87%
rename from toolchain/check/testdata/index/fail_expression_category.carbon
rename to toolchain/check/testdata/index/fail_expr_category.carbon
index a99bdb9d60fc..b3bc34bcd803 100644
--- a/toolchain/check/testdata/index/fail_expression_category.carbon
+++ b/toolchain/check/testdata/index/fail_expr_category.carbon
@@ -8,22 +8,22 @@ fn F() -> [i32; 3];
 
 fn G(b: [i32; 3]) {
   // Indexing an array value gives a value.
-  // CHECK:STDERR: fail_expression_category.carbon:[[@LINE+3]]:18: ERROR: Cannot take the address of non-reference expression.
+  // CHECK:STDERR: fail_expr_category.carbon:[[@LINE+3]]:18: ERROR: Cannot take the address of non-reference expression.
   // CHECK:STDERR:   var pb: i32* = &b[0];
   // CHECK:STDERR:                  ^
   var pb: i32* = &b[0];
-  // CHECK:STDERR: fail_expression_category.carbon:[[@LINE+3]]:6: ERROR: Expression is not assignable.
+  // CHECK:STDERR: fail_expr_category.carbon:[[@LINE+3]]:6: ERROR: Expression is not assignable.
   // CHECK:STDERR:   b[0] = 4;
   // CHECK:STDERR:      ^
   b[0] = 4;
 
   // Indexing an ephemeral reference (materialized from an initializing
   // expression) gives a value.
-  // CHECK:STDERR: fail_expression_category.carbon:[[@LINE+3]]:18: ERROR: Cannot take the address of non-reference expression.
+  // CHECK:STDERR: fail_expr_category.carbon:[[@LINE+3]]:18: ERROR: Cannot take the address of non-reference expression.
   // CHECK:STDERR:   var pf: i32* = &F()[0];
   // CHECK:STDERR:                  ^
   var pf: i32* = &F()[0];
-  // CHECK:STDERR: fail_expression_category.carbon:[[@LINE+3]]:8: ERROR: Expression is not assignable.
+  // CHECK:STDERR: fail_expr_category.carbon:[[@LINE+3]]:8: ERROR: Expression is not assignable.
   // CHECK:STDERR:   F()[0] = 4;
   // CHECK:STDERR:        ^
   F()[0] = 4;
@@ -33,7 +33,7 @@ fn G(b: [i32; 3]) {
 // CHECK:STDOUT:   %.loc7: type = ptr_type [i32; 3]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: file "fail_expression_category.carbon" {
+// CHECK:STDOUT: file "fail_expr_category.carbon" {
 // CHECK:STDOUT:   %F: <function> = fn_decl @F
 // CHECK:STDOUT:   %G: <function> = fn_decl @G
 // CHECK:STDOUT: }
diff --git a/toolchain/check/testdata/pointer/fail_dereference_error.carbon b/toolchain/check/testdata/pointer/fail_deref_error.carbon
similarity index 77%
rename from toolchain/check/testdata/pointer/fail_dereference_error.carbon
rename to toolchain/check/testdata/pointer/fail_deref_error.carbon
index a3a6a00b4c94..cb514450216a 100644
--- a/toolchain/check/testdata/pointer/fail_dereference_error.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_error.carbon
@@ -4,12 +4,12 @@
 //
 // AUTOUPDATE
 
-// CHECK:STDERR: fail_dereference_error.carbon:[[@LINE+3]]:15: ERROR: Name `undeclared` not found.
+// CHECK:STDERR: fail_deref_error.carbon:[[@LINE+3]]:15: ERROR: Name `undeclared` not found.
 // CHECK:STDERR: let n: i32 = *undeclared;
 // CHECK:STDERR:               ^~~~~~~~~~
 let n: i32 = *undeclared;
 
-// CHECK:STDOUT: file "fail_dereference_error.carbon" {
+// CHECK:STDOUT: file "fail_deref_error.carbon" {
 // CHECK:STDOUT:   %undeclared.ref: <error> = name_ref undeclared, <error>
 // CHECK:STDOUT:   %.loc10: ref <error> = deref <error>
 // CHECK:STDOUT:   %n: i32 = bind_name n, <error>
diff --git a/toolchain/check/testdata/pointer/fail_dereference_function.carbon b/toolchain/check/testdata/pointer/fail_deref_function.carbon
similarity index 77%
rename from toolchain/check/testdata/pointer/fail_dereference_function.carbon
rename to toolchain/check/testdata/pointer/fail_deref_function.carbon
index f77cabfb37e1..cedbbc264b91 100644
--- a/toolchain/check/testdata/pointer/fail_dereference_function.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_function.carbon
@@ -5,13 +5,13 @@
 // AUTOUPDATE
 
 fn A() {
-  // CHECK:STDERR: fail_dereference_function.carbon:[[@LINE+3]]:4: ERROR: Expression cannot be used as a value.
+  // CHECK:STDERR: fail_deref_function.carbon:[[@LINE+3]]:4: ERROR: Expression cannot be used as a value.
   // CHECK:STDERR:   *A;
   // CHECK:STDERR:    ^
   *A;
 }
 
-// CHECK:STDOUT: file "fail_dereference_function.carbon" {
+// CHECK:STDOUT: file "fail_deref_function.carbon" {
 // CHECK:STDOUT:   %A: <function> = fn_decl @A
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/pointer/fail_dereference_namespace.carbon b/toolchain/check/testdata/pointer/fail_deref_namespace.carbon
similarity index 78%
rename from toolchain/check/testdata/pointer/fail_dereference_namespace.carbon
rename to toolchain/check/testdata/pointer/fail_deref_namespace.carbon
index fde508591824..28208e437d4e 100644
--- a/toolchain/check/testdata/pointer/fail_dereference_namespace.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_namespace.carbon
@@ -7,13 +7,13 @@
 namespace A;
 
 fn F() {
-  // CHECK:STDERR: fail_dereference_namespace.carbon:[[@LINE+3]]:4: ERROR: Expression cannot be used as a value.
+  // CHECK:STDERR: fail_deref_namespace.carbon:[[@LINE+3]]:4: ERROR: Expression cannot be used as a value.
   // CHECK:STDERR:   *A;
   // CHECK:STDERR:    ^
   *A;
 }
 
-// CHECK:STDOUT: file "fail_dereference_namespace.carbon" {
+// CHECK:STDOUT: file "fail_deref_namespace.carbon" {
 // CHECK:STDOUT:   %.loc7: <namespace> = namespace {}
 // CHECK:STDOUT:   %F: <function> = fn_decl @F
 // CHECK:STDOUT: }
diff --git a/toolchain/check/testdata/pointer/fail_dereference_not_pointer.carbon b/toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon
similarity index 74%
rename from toolchain/check/testdata/pointer/fail_dereference_not_pointer.carbon
rename to toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon
index f4d8a7f6c7ec..8cd00735841b 100644
--- a/toolchain/check/testdata/pointer/fail_dereference_not_pointer.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon
@@ -5,15 +5,15 @@
 // AUTOUPDATE
 
 fn Deref(n: i32) {
-  // CHECK:STDERR: fail_dereference_not_pointer.carbon:[[@LINE+3]]:3: ERROR: Cannot dereference operand of non-pointer type `i32`.
+  // CHECK:STDERR: fail_deref_not_pointer.carbon:[[@LINE+3]]:3: ERROR: Cannot dereference operand of non-pointer type `i32`.
   // CHECK:STDERR:   *n;
   // CHECK:STDERR:   ^
   *n;
-  // CHECK:STDERR: fail_dereference_not_pointer.carbon:[[@LINE+3]]:3: ERROR: Cannot dereference operand of non-pointer type `() as type`.
+  // CHECK:STDERR: fail_deref_not_pointer.carbon:[[@LINE+3]]:3: ERROR: Cannot dereference operand of non-pointer type `() as type`.
   // CHECK:STDERR:   *();
   // CHECK:STDERR:   ^
   *();
-  // CHECK:STDERR: fail_dereference_not_pointer.carbon:[[@LINE+3]]:3: ERROR: Cannot dereference operand of non-pointer type `{} as type`.
+  // CHECK:STDERR: fail_deref_not_pointer.carbon:[[@LINE+3]]:3: ERROR: Cannot dereference operand of non-pointer type `{} as type`.
   // CHECK:STDERR:   *{};
   // CHECK:STDERR:   ^
   *{};
@@ -24,7 +24,7 @@ fn Deref(n: i32) {
 // CHECK:STDOUT:   %.loc19: type = struct_type {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: file "fail_dereference_not_pointer.carbon" {
+// CHECK:STDOUT: file "fail_deref_not_pointer.carbon" {
 // CHECK:STDOUT:   %Deref: <function> = fn_decl @Deref
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/pointer/fail_dereference_type.carbon b/toolchain/check/testdata/pointer/fail_deref_type.carbon
similarity index 62%
rename from toolchain/check/testdata/pointer/fail_dereference_type.carbon
rename to toolchain/check/testdata/pointer/fail_deref_type.carbon
index d37e1180a859..662cc71f3f45 100644
--- a/toolchain/check/testdata/pointer/fail_dereference_type.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_type.carbon
@@ -4,15 +4,15 @@
 //
 // AUTOUPDATE
 
-// CHECK:STDERR: fail_dereference_type.carbon:[[@LINE+6]]:8: ERROR: Cannot dereference operand of non-pointer type `type`.
+// CHECK:STDERR: fail_deref_type.carbon:[[@LINE+6]]:8: ERROR: Cannot dereference operand of non-pointer type `type`.
 // CHECK:STDERR: var p: *i32;
 // CHECK:STDERR:        ^
-// CHECK:STDERR: fail_dereference_type.carbon:[[@LINE+3]]:8: To form a pointer type, write the `*` after the pointee type.
+// CHECK:STDERR: fail_deref_type.carbon:[[@LINE+3]]:8: To form a pointer type, write the `*` after the pointee type.
 // CHECK:STDERR: var p: *i32;
 // CHECK:STDERR:        ^
 var p: *i32;
 
-// CHECK:STDOUT: file "fail_dereference_type.carbon" {
+// CHECK:STDOUT: file "fail_deref_type.carbon" {
 // CHECK:STDOUT:   %.loc13: ref <error> = deref i32
 // CHECK:STDOUT:   %p.var: ref <error> = var p
 // CHECK:STDOUT:   %p: ref <error> = bind_name p, %p.var
diff --git a/toolchain/lower/testdata/if_expression/basic.carbon b/toolchain/lower/testdata/if_expr/basic.carbon
similarity index 100%
rename from toolchain/lower/testdata/if_expression/basic.carbon
rename to toolchain/lower/testdata/if_expr/basic.carbon
diff --git a/toolchain/lower/testdata/if_expression/empty_block.carbon b/toolchain/lower/testdata/if_expr/empty_block.carbon
similarity index 100%
rename from toolchain/lower/testdata/if_expression/empty_block.carbon
rename to toolchain/lower/testdata/if_expr/empty_block.carbon
diff --git a/toolchain/parse/testdata/if_expression/basic.carbon b/toolchain/parse/testdata/if_expr/basic.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/basic.carbon
rename to toolchain/parse/testdata/if_expr/basic.carbon
diff --git a/toolchain/parse/testdata/if_expression/fail_condition_missing.carbon b/toolchain/parse/testdata/if_expr/fail_condition_missing.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/fail_condition_missing.carbon
rename to toolchain/parse/testdata/if_expr/fail_condition_missing.carbon
diff --git a/toolchain/parse/testdata/if_expression/fail_else_expr_missing.carbon b/toolchain/parse/testdata/if_expr/fail_else_expr_missing.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/fail_else_expr_missing.carbon
rename to toolchain/parse/testdata/if_expr/fail_else_expr_missing.carbon
diff --git a/toolchain/parse/testdata/if_expression/fail_else_missing.carbon b/toolchain/parse/testdata/if_expr/fail_else_missing.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/fail_else_missing.carbon
rename to toolchain/parse/testdata/if_expr/fail_else_missing.carbon
diff --git a/toolchain/parse/testdata/if_expression/fail_then_expr_missing.carbon b/toolchain/parse/testdata/if_expr/fail_then_expr_missing.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/fail_then_expr_missing.carbon
rename to toolchain/parse/testdata/if_expr/fail_then_expr_missing.carbon
diff --git a/toolchain/parse/testdata/if_expression/fail_then_missing.carbon b/toolchain/parse/testdata/if_expr/fail_then_missing.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/fail_then_missing.carbon
rename to toolchain/parse/testdata/if_expr/fail_then_missing.carbon
diff --git a/toolchain/parse/testdata/if_expression/fail_top_level_if.carbon b/toolchain/parse/testdata/if_expr/fail_top_level_if.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/fail_top_level_if.carbon
rename to toolchain/parse/testdata/if_expr/fail_top_level_if.carbon
diff --git a/toolchain/parse/testdata/if_expression/in_type.carbon b/toolchain/parse/testdata/if_expr/in_type.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/in_type.carbon
rename to toolchain/parse/testdata/if_expr/in_type.carbon
diff --git a/toolchain/parse/testdata/if_expression/precedence.carbon b/toolchain/parse/testdata/if_expr/precedence.carbon
similarity index 100%
rename from toolchain/parse/testdata/if_expression/precedence.carbon
rename to toolchain/parse/testdata/if_expr/precedence.carbon
diff --git a/toolchain/parse/testdata/pointer/fail_pointer_type_in_expression.carbon b/toolchain/parse/testdata/pointer/fail_pointer_type_in_expr.carbon
similarity index 86%
rename from toolchain/parse/testdata/pointer/fail_pointer_type_in_expression.carbon
rename to toolchain/parse/testdata/pointer/fail_pointer_type_in_expr.carbon
index f9a5be71b052..d4bd93b5e145 100644
--- a/toolchain/parse/testdata/pointer/fail_pointer_type_in_expression.carbon
+++ b/toolchain/parse/testdata/pointer/fail_pointer_type_in_expr.carbon
@@ -9,30 +9,30 @@ fn F() -> i32 {
   // error, so that it's clear what ambiguity we're referring to.
   // TODO: Improve error recovery so that we recover as `3 * (i32*) * 4`, not
   // as `(3 * i32)* * 4`, to suppress the second error here.
-  // CHECK:STDERR: fail_pointer_type_in_expression.carbon:[[@LINE+6]]:17: ERROR: Parentheses are required to disambiguate operator precedence.
+  // CHECK:STDERR: fail_pointer_type_in_expr.carbon:[[@LINE+6]]:17: ERROR: Parentheses are required to disambiguate operator precedence.
   // CHECK:STDERR:   return 3 * i32* * 4;
   // CHECK:STDERR:                 ^
-  // CHECK:STDERR: fail_pointer_type_in_expression.carbon:[[@LINE+3]]:19: ERROR: Parentheses are required to disambiguate operator precedence.
+  // CHECK:STDERR: fail_pointer_type_in_expr.carbon:[[@LINE+3]]:19: ERROR: Parentheses are required to disambiguate operator precedence.
   // CHECK:STDERR:   return 3 * i32* * 4;
   // CHECK:STDERR:                   ^
   return 3 * i32* * 4;
 }
 
 fn G() -> i32 {
-  // CHECK:STDERR: fail_pointer_type_in_expression.carbon:[[@LINE+3]]:15: ERROR: Parentheses are required to disambiguate operator precedence.
+  // CHECK:STDERR: fail_pointer_type_in_expr.carbon:[[@LINE+3]]:15: ERROR: Parentheses are required to disambiguate operator precedence.
   // CHECK:STDERR:   return i32* + 4;
   // CHECK:STDERR:               ^
   return i32* + 4;
 }
 
 fn H() -> i32 {
-  // CHECK:STDERR: fail_pointer_type_in_expression.carbon:[[@LINE+3]]:14: ERROR: Parentheses are required to disambiguate operator precedence.
+  // CHECK:STDERR: fail_pointer_type_in_expr.carbon:[[@LINE+3]]:14: ERROR: Parentheses are required to disambiguate operator precedence.
   // CHECK:STDERR:   return *i32*;
   // CHECK:STDERR:              ^
   return *i32*;
 }
 
-// CHECK:STDOUT: - filename: fail_pointer_type_in_expression.carbon
+// CHECK:STDOUT: - filename: fail_pointer_type_in_expr.carbon
 // CHECK:STDOUT:   parse_tree: [
 // CHECK:STDOUT:     {kind: 'FileStart', text: ''},
 // CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},