diff --git a/HACKING.md b/HACKING.md
index 0a6745015d..66c8f053ef 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -147,14 +147,13 @@ directory. All `.ncl` files in this directory are automatically converted into
 Rust integration tests, which run the file and assert that no errors were
 raised during evaluation.
 
-Each of these `.ncl` files is structured as an array of `Bool` expressions, which
-is ultimately passed to a `check` function defined in
-`core/tests/integration/pass/lib/assert.ncl`.
-This function applies an `Assert` contract to each value in the array, which
-checks that the value it is applied to evaluates to `true`. The benefit of using
-a contract for this is that if a test fails we can simply run the file directly
-using Nickel, which gives better error messages than the ones we get by default
-from `cargo test`.
+Each of these `.ncl` files is structured as an array of `Bool` expressions,
+which is ultimately passed to `std.contract.check` function defined in the
+standard library. This function applies an `Assert` (`std.test.Assert`)
+contract to each value in the array, which checks that the value it is applied
+to evaluates to `true`. The benefit of using a contract for this is that if a
+test fails we can simply run the file directly using Nickel, which gives better
+error messages than the ones we get by default from `cargo test`.
 
 Tests which are expected to fail may be written in Rust in `core/tests/integration`.
 However, simple failure test cases can make use of the test annotation support
diff --git a/core/stdlib/std.ncl b/core/stdlib/std.ncl
index fe3b16952a..08bec6f8e7 100644
--- a/core/stdlib/std.ncl
+++ b/core/stdlib/std.ncl
@@ -792,6 +792,28 @@
   },
 
   contract = {
+    Assert
+      | doc m%"
+        A contract that checks if its argument is the boolean true.
+
+        We could get by just using arrays of boolean tests and `std.array.all`.
+
+        However, this contract provides fine-grained error reporting,
+        pinpointoing the exact expression that failed in an array of tests, as
+        opposed to the pure boolean solution.
+
+        # Examples
+
+        ```nickel
+        1 == 2 | std.test.Assert
+         => error: contract broken by a value
+
+        1 == 1 | std.test.Assert
+         => true
+        ```
+        "%
+      = fun l x => if x then true else %blame% l,
+
     Equal
       | doc m%"
         `Equal` is a contract enforcing equality to a given constant.
@@ -3064,6 +3086,44 @@
       = fun s => %enum_from_str% s,
   },
 
+  test = {
+    Assert
+      | doc m%"
+        A contract that checks if its argument is the boolean true.
+
+        # Examples
+
+        ```nickel
+        1 == 2 | std.test.Assert
+         => error: contract broken by a value
+
+        1 == 1 | std.test.Assert
+         => true
+        ```
+        "%
+      = fun l x => if x then true else %blame% l,
+
+    # We statically type `assert_all` because (x | Assert) is not of type bool.
+    # We could use additional contracts to make it work but it's not worth the
+    # hassle, given the size of the function.
+    assert_all
+      | doc m%"
+        Asserts that all the elements of an array are equal to true. Applies the
+        `std.test.Assert` contract on each element of the given array.
+
+        Evalutes to `true` if all the elements of the array are equal to true,
+        or fails with a contract error otherwise.
+
+        # Example
+
+        ```nickel
+        [ (1 == 2), (1 == 1), (1 == 3) ] |> std.test.assert_all
+         => error: contract broken by a value
+        ```
+        "%
+      = std.array.fold_left (fun acc test => (test | Assert) && acc) true,
+  },
+
   is_number
     : Dyn -> Bool
     | doc m%"
diff --git a/core/tests/integration/inputs/adts/enum_primops.ncl b/core/tests/integration/inputs/adts/enum_primops.ncl
index 9ff67836c0..eb7e261bae 100644
--- a/core/tests/integration/inputs/adts/enum_primops.ncl
+++ b/core/tests/integration/inputs/adts/enum_primops.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   %enum_unwrap_variant% ('Left (1+1)) == 2,
@@ -8,4 +8,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   %enum_get_tag% 'Right == 'Right,
   %enum_get_tag% ('Right "stuff") == 'Right,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/contracts/contracts.ncl b/core/tests/integration/inputs/contracts/contracts.ncl
index 8c4959a4e8..7dc66a6fa8 100644
--- a/core/tests/integration/inputs/contracts/contracts.ncl
+++ b/core/tests/integration/inputs/contracts/contracts.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, Assert, ..} = import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 
 [
   let AlwaysTrue = fun l t =>
@@ -179,4 +179,4 @@ let {check, Assert, ..} = import "../lib/assert.ncl" in
   in
   tag == 'some_tag,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/contracts/let_order.ncl b/core/tests/integration/inputs/contracts/let_order.ncl
index 3812b30d72..39f014ec01 100644
--- a/core/tests/integration/inputs/contracts/let_order.ncl
+++ b/core/tests/integration/inputs/contracts/let_order.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let { check, Assert, .. } = import "../lib/assert.ncl" in
+
 let ConstantTrue = fun _label value => std.seq value true in
 [
   let foo | ConstantTrue | Bool = "not a bool" in
@@ -12,4 +12,4 @@ let ConstantTrue = fun _label value => std.seq value true in
       = "still not a bool"
   }.foo
 ]
-|> check
\ No newline at end of file
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/contracts/types_dont_propagate.ncl b/core/tests/integration/inputs/contracts/types_dont_propagate.ncl
index 874be21308..def12e0f18 100644
--- a/core/tests/integration/inputs/contracts/types_dont_propagate.ncl
+++ b/core/tests/integration/inputs/contracts/types_dont_propagate.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # check that a record type literal is indeed converted to the corresponding
@@ -21,4 +21,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   & {foo | force = false, bar | force = true})
   == {foo = false, bar = true},
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/arrays.ncl b/core/tests/integration/inputs/core/arrays.ncl
index fc99dee747..262f56842c 100644
--- a/core/tests/integration/inputs/core/arrays.ncl
+++ b/core/tests/integration/inputs/core/arrays.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # accesses
@@ -49,4 +49,4 @@ let {check, ..} = import "../lib/assert.ncl" in
 
   std.array.map_with_index (+) [1, 2, 3] == [1, 3, 5],
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/basics.ncl b/core/tests/integration/inputs/core/basics.ncl
index eb332f866b..9fe46df898 100644
--- a/core/tests/integration/inputs/core/basics.ncl
+++ b/core/tests/integration/inputs/core/basics.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # basic arithmetic
@@ -35,4 +35,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   # This test checks that the terms of a match are closured
   let x = 3 in ((3 + 2) |> match { 'foo => 1, _ => x}) == 3,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/builtins.ncl b/core/tests/integration/inputs/core/builtins.ncl
index 9fef0b9924..dbf15127ed 100644
--- a/core/tests/integration/inputs/core/builtins.ncl
+++ b/core/tests/integration/inputs/core/builtins.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # is_record
@@ -28,4 +28,4 @@ let {check, ..} = import "../lib/assert.ncl" in
    |> std.deserialize 'Json
    == [3,4],
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/curried_dot.ncl b/core/tests/integration/inputs/core/curried_dot.ncl
index 073b0bce12..83e04a94ea 100644
--- a/core/tests/integration/inputs/core/curried_dot.ncl
+++ b/core/tests/integration/inputs/core/curried_dot.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 let record = {foo = 1, bar = { baz = 2 }} in
 let field = "bar" in
@@ -9,4 +9,4 @@ let part = "ba" in
   (.) record field == { baz = 2 },
   let res = (.) record field == {baz = 2} in res,
   (.) record "%{part}r" == { baz = 2 },
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/eq.ncl b/core/tests/integration/inputs/core/eq.ncl
index f74dff94d2..f721373c3d 100644
--- a/core/tests/integration/inputs/core/eq.ncl
+++ b/core/tests/integration/inputs/core/eq.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # basic
@@ -84,4 +84,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   'Left 2 != 'Right 2,
   'Up [1,2,3] == 'Up [0+1,1+1,2+1],
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/fibo.ncl b/core/tests/integration/inputs/core/fibo.ncl
index 7d16f76478..771aa18f4c 100644
--- a/core/tests/integration/inputs/core/fibo.ncl
+++ b/core/tests/integration/inputs/core/fibo.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {Assert, ..} = import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 
 let Y | ((Number -> Number) -> Number -> Number) -> Number -> Number = fun f => (fun x => f (x x)) (fun x => f (x x)) in
 let dec : Number -> Number = fun x => x + (-1) in
diff --git a/core/tests/integration/inputs/core/functions.ncl b/core/tests/integration/inputs/core/functions.ncl
index 2e48a3008a..0c26f9c672 100644
--- a/core/tests/integration/inputs/core/functions.ncl
+++ b/core/tests/integration/inputs/core/functions.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   (fun x => x) 3 == 3,
@@ -16,4 +16,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     g true
     == 4,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/import.ncl b/core/tests/integration/inputs/core/import.ncl
index 1c37d0e047..acbb353672 100644
--- a/core/tests/integration/inputs/core/import.ncl
+++ b/core/tests/integration/inputs/core/import.ncl
@@ -1,3 +1,3 @@
 # test.type = 'pass'
-let { Assert, .. } = import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 ((import "../lib/imported.ncl") 3 == 3 | Assert)
diff --git a/core/tests/integration/inputs/core/numbers.ncl b/core/tests/integration/inputs/core/numbers.ncl
index 8b0a59f819..d7a60e8003 100644
--- a/core/tests/integration/inputs/core/numbers.ncl
+++ b/core/tests/integration/inputs/core/numbers.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   5 + 5 == 10,
@@ -7,4 +7,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   1e6 == 1000000,
   1e+3 / 2e-3 == 0.5e6,
 ]
-|> check
\ No newline at end of file
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/records.ncl b/core/tests/integration/inputs/core/records.ncl
index a53cb4e23e..a131e1c12d 100644
--- a/core/tests/integration/inputs/core/records.ncl
+++ b/core/tests/integration/inputs/core/records.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let { check, .. } = import "../lib/assert.ncl" in
+
 
 [
   # accesses
@@ -171,4 +171,4 @@ let { check, .. } = import "../lib/assert.ncl" in
     && r.force == "no"
   )
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/core/recursive_let.ncl b/core/tests/integration/inputs/core/recursive_let.ncl
index d3715acca6..21428503a0 100644
--- a/core/tests/integration/inputs/core/recursive_let.ncl
+++ b/core/tests/integration/inputs/core/recursive_let.ncl
@@ -1,8 +1,8 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   let rec f = fun n => if n == 0 then n else f (n - 1) in f 10 == 0,
   let rec fib = fun n => if n == 0 || n == 1 then 1 else fib (n - 1) + fib (n - 2) in fib 5 == 8,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/imports/yaml_import.ncl b/core/tests/integration/inputs/imports/yaml_import.ncl
index 93e4af8f9d..474b238417 100644
--- a/core/tests/integration/inputs/imports/yaml_import.ncl
+++ b/core/tests/integration/inputs/imports/yaml_import.ncl
@@ -1,6 +1,6 @@
 # test.type = 'pass'
 
-let {check, ..} = import "../lib/assert.ncl" in
+
 [
   (import "imported/empty.yaml") == null,
 
@@ -9,4 +9,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     { type = "event", id = 2 }
   ],
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/lib/assert.ncl b/core/tests/integration/inputs/lib/assert.ncl
deleted file mode 100644
index 54148ba808..0000000000
--- a/core/tests/integration/inputs/lib/assert.ncl
+++ /dev/null
@@ -1,31 +0,0 @@
-# test.type = 'skip'
-{
-  Assert | doc m%"
-    A contract that checks if its argument is the boolean true.
-
-    We could get by just using arrays of boolean tests and `array.all`.
-
-    However, we apply this contract to each test instead because it provides
-    fine-grained error reporting, pinpointoing the exact expression that failed
-    in an array of tests, as opposed to the pure boolean solution.
-    "%
-    = fun l x => x || %blame% l,
-  # We can't use a static type because x | Assert is not of type bool.
-  # We could use additional contracts to make it work but it's not worth the
-  # hassle.
-  check | doc m%"
-    unchecked type: Array Bool -> Bool
-
-    Check an array of tests. Apply the `Assert` contract on each element of the
-    given array.
-
-    `check tests` It is semantically equivalent to
-
-    ```nickel
-    (array.all function.id tests) | Assert
-    ```
-
-    But will give more precise error reporting when one test fails.
-    "%
-    = std.array.fold_left (fun acc test => (test | Assert) && acc) true,
-}
diff --git a/core/tests/integration/inputs/merging/adts.ncl b/core/tests/integration/inputs/merging/adts.ncl
index fa7ec12783..6d266257bf 100644
--- a/core/tests/integration/inputs/merging/adts.ncl
+++ b/core/tests/integration/inputs/merging/adts.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let { check, .. } = import "../lib/assert.ncl" in
+
 
 [
   'Foo true & 'Foo true == 'Foo true,
@@ -13,4 +13,4 @@ let { check, .. } = import "../lib/assert.ncl" in
   & { two.b = 1, one = 'Qux {c = 0} }
   == { one = 'Qux { a = 1, b = 1, c = 0 }, two = { a = 1, b = 1 } },
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/merging/array-merge.ncl b/core/tests/integration/inputs/merging/array-merge.ncl
index 514e4307c3..17a93d48ee 100644
--- a/core/tests/integration/inputs/merging/array-merge.ncl
+++ b/core/tests/integration/inputs/merging/array-merge.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # array pointwise merging
@@ -25,4 +25,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   & ([0 + 0, 1 + 0, 2 + 0] | Array AddOne)
   == [1, 2, 3],
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/merging/lazy-propagation.ncl b/core/tests/integration/inputs/merging/lazy-propagation.ncl
index 75bde1bd13..6bb6789a7a 100644
--- a/core/tests/integration/inputs/merging/lazy-propagation.ncl
+++ b/core/tests/integration/inputs/merging/lazy-propagation.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, Assert, ..} = import "../lib/assert.ncl" in
+
 
 # tests related to RFC005. Check in particular that the motivating examples of
 # RFC005 are indeed fixed by lazy propagation.
@@ -44,4 +44,4 @@ let {check, Assert, ..} = import "../lib/assert.ncl" in
   & {bar = "bar"})
   == {foo = 5, bar = "bar"},
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/merging/metavalues.ncl b/core/tests/integration/inputs/merging/metavalues.ncl
index 3b28221167..8820d9ced2 100644
--- a/core/tests/integration/inputs/merging/metavalues.ncl
+++ b/core/tests/integration/inputs/merging/metavalues.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, Assert, ..} = import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 
 [
   {val | default | Number = 10}.val == 10,
@@ -132,4 +132,4 @@ let {check, Assert, ..} = import "../lib/assert.ncl" in
     (%fields% value == ["foo", "opt"] | Assert)
   ),
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/merging/multiple_overrides.ncl b/core/tests/integration/inputs/merging/multiple_overrides.ncl
index 8ebe7adbc5..3ef75e2908 100644
--- a/core/tests/integration/inputs/merging/multiple_overrides.ncl
+++ b/core/tests/integration/inputs/merging/multiple_overrides.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # regression test for issue #908 (https://github.com/tweag/nickel/issues/908)
@@ -121,6 +121,6 @@ let {check, ..} = import "../lib/assert.ncl" in
       fst_data = "override",
       snd_data = "override",
     }
-  ] |> check,
+  ] |> std.test.assert_all,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/merging/overriding.ncl b/core/tests/integration/inputs/merging/overriding.ncl
index b2170664d3..4a63cdee3f 100644
--- a/core/tests/integration/inputs/merging/overriding.ncl
+++ b/core/tests/integration/inputs/merging/overriding.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   {foo | default = 1} & {foo = 2} == {foo = 2},
@@ -72,4 +72,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   ({foo | default = 1, bar = foo} & {foo = 2}).bar == 2,
   ({foo | default = 1, bar = foo, baz = bar} & {foo = 2}).baz == 2,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/merging/priorities.ncl b/core/tests/integration/inputs/merging/priorities.ncl
index b9899633ca..5d3d21daa1 100644
--- a/core/tests/integration/inputs/merging/priorities.ncl
+++ b/core/tests/integration/inputs/merging/priorities.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {Assert, check, ..} =  import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 
 [
   let block1 = {
@@ -83,4 +83,4 @@ let {Assert, check, ..} =  import "../lib/assert.ncl" in
   # } in
   # {val | rec force = x } & {val = {foo = 0, bar = 10}}
   #   == {val = {bar = 10, foo = 1 + 2 + 10}} | Assert,
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/parsing/annotations.ncl b/core/tests/integration/inputs/parsing/annotations.ncl
index ec86a45bf5..67e4d2f5c0 100644
--- a/core/tests/integration/inputs/parsing/annotations.ncl
+++ b/core/tests/integration/inputs/parsing/annotations.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, Assert, ..} = import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 
 [
   # left_annot_precedence
@@ -23,4 +23,4 @@ let {check, Assert, ..} = import "../lib/assert.ncl" in
   # others_precedence
   ((fun x => x | Assert) true),
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/parsing/identifiers.ncl b/core/tests/integration/inputs/parsing/identifiers.ncl
index 22ff98bfaa..61448bedf8 100644
--- a/core/tests/integration/inputs/parsing/identifiers.ncl
+++ b/core/tests/integration/inputs/parsing/identifiers.ncl
@@ -1,8 +1,8 @@
 # test.type = 'pass'
-let {Assert, check, ..} = import "../lib/assert.ncl" in
+
 
 [
   let this-isn't-invalid = true in this-isn't-invalid,
   let ___multi_underscore_start = true in ___multi_underscore_start,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/arrays.ncl b/core/tests/integration/inputs/pattern-matching/arrays.ncl
index f0d6f3fe83..b797f4993b 100644
--- a/core/tests/integration/inputs/pattern-matching/arrays.ncl
+++ b/core/tests/integration/inputs/pattern-matching/arrays.ncl
@@ -1,6 +1,4 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
-
 [
   [] |> match {
     [x] => false,
@@ -51,4 +49,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     _ => false,
   }
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/basics.ncl b/core/tests/integration/inputs/pattern-matching/basics.ncl
index 0f0ff908ce..dda27ebe65 100644
--- a/core/tests/integration/inputs/pattern-matching/basics.ncl
+++ b/core/tests/integration/inputs/pattern-matching/basics.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   {foo = 1, bar = 2} |> match {
@@ -59,4 +59,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   |> eval {}
   |> (==) 11,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/contracts.ncl b/core/tests/integration/inputs/pattern-matching/contracts.ncl
index d31afef755..bc6811dbb9 100644
--- a/core/tests/integration/inputs/pattern-matching/contracts.ncl
+++ b/core/tests/integration/inputs/pattern-matching/contracts.ncl
@@ -1,9 +1,9 @@
 # test.type = 'pass'
 
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   {foo = {}} |> match { {foo = {bar ? 5}} => true},
   {foo = {}} |> match { {foo = {bar | String }} => false, {foo} => true},
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/default_value.ncl b/core/tests/integration/inputs/pattern-matching/default_value.ncl
index 66aa899b73..ea45bb8fdd 100644
--- a/core/tests/integration/inputs/pattern-matching/default_value.ncl
+++ b/core/tests/integration/inputs/pattern-matching/default_value.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   let {x ? 1, y ? 1, z} = {z = 1} in (x + y + z) == 3,
@@ -13,4 +13,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     _ => false,
   },
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/enum_after_wildcard.ncl b/core/tests/integration/inputs/pattern-matching/enum_after_wildcard.ncl
index c9efa32001..bbc17df2b1 100644
--- a/core/tests/integration/inputs/pattern-matching/enum_after_wildcard.ncl
+++ b/core/tests/integration/inputs/pattern-matching/enum_after_wildcard.ncl
@@ -8,7 +8,7 @@
 # This test ensure it correctly handle a wildcard being used before the end of
 # the match expression, which was mishandled previously (branches after the
 # wildcard would be selected if they matched).
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   'Foo |> match {
@@ -28,4 +28,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     _ => false,
   },
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/guards.ncl b/core/tests/integration/inputs/pattern-matching/guards.ncl
index f37b1bcc8b..e928920144 100644
--- a/core/tests/integration/inputs/pattern-matching/guards.ncl
+++ b/core/tests/integration/inputs/pattern-matching/guards.ncl
@@ -1,6 +1,4 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
-
 [
   'Ok |> match {
     'Ok if false => false,
@@ -29,4 +27,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     _ => false
   }
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/pattern-matching/wildcards.ncl b/core/tests/integration/inputs/pattern-matching/wildcards.ncl
index 7f849bbc77..baba74afcc 100644
--- a/core/tests/integration/inputs/pattern-matching/wildcards.ncl
+++ b/core/tests/integration/inputs/pattern-matching/wildcards.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   {foo = 1, bar = 2} |> match {
@@ -21,4 +21,4 @@ let {check, ..} = import "../lib/assert.ncl" in
     'Point _ => true,
   },
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/records/record_defs.ncl b/core/tests/integration/inputs/records/record_defs.ncl
index dd7fe59d54..d22913c57c 100644
--- a/core/tests/integration/inputs/records/record_defs.ncl
+++ b/core/tests/integration/inputs/records/record_defs.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # piecewise_definitions
@@ -41,4 +41,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   let x = "foo" in {"%{x}" = bar, bar = 1} == {foo = 1, bar = 1},
   ({"%foo"."%bar".baz = other + 1, other = 0}."%foo"."%bar".baz == 1),
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/serialization/serialize.ncl b/core/tests/integration/inputs/serialization/serialize.ncl
index adfa0d1c90..6a285d1d7e 100644
--- a/core/tests/integration/inputs/serialization/serialize.ncl
+++ b/core/tests/integration/inputs/serialization/serialize.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 let assertSerInv = fun x =>
     let assertAux = fun format x =>
@@ -63,4 +63,4 @@ let assertDeserInv = fun x =>
   let ext = {foo = {some = {}}} in
   assertSerInv (base & ext),
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/record_empty_optional_ops.ncl b/core/tests/integration/inputs/stdlib/record_empty_optional_ops.ncl
index 01cc078144..31a31a1aa4 100644
--- a/core/tests/integration/inputs/stdlib/record_empty_optional_ops.ncl
+++ b/core/tests/integration/inputs/stdlib/record_empty_optional_ops.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let { check, .. } = import "../lib/assert.ncl" in
+
 let { record, .. } = std in
 
 [
@@ -23,4 +23,4 @@ let { record, .. } = std in
   std.record.has_field_with_opts "c" { a = 1, b = 2, c | optional } == true,
   std.record.has_field_with_opts "c" ({ a = 1, b = 2 } | { a, b, c | optional }) == true,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_contains_find_replace.ncl b/core/tests/integration/inputs/stdlib/string_contains_find_replace.ncl
index b26cbbfd75..a9c3cca7db 100644
--- a/core/tests/integration/inputs/stdlib/string_contains_find_replace.ncl
+++ b/core/tests/integration/inputs/stdlib/string_contains_find_replace.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -44,4 +44,4 @@ let {string, ..} = std in
   string.find "\\d" "no numeral" == { matched = "", index = -1, groups = []},
   string.find "❤️" "👨‍❤️‍💋‍👨" == { matched = "", index = -1, groups = []},
   string.find "❤️" "👨‍❤️‍💋‍👨❤️" == { matched = "❤️", index = 1, groups = [] },
-  ] |> check
+  ] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_contracts.ncl b/core/tests/integration/inputs/stdlib/string_contracts.ncl
index 051edc888c..3d8eeb1077 100644
--- a/core/tests/integration/inputs/stdlib/string_contracts.ncl
+++ b/core/tests/integration/inputs/stdlib/string_contracts.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -37,4 +37,4 @@ let {string, ..} = std in
   ("_" | string.NonEmpty) == "_",
   ("a" | string.NonEmpty) == "a",
   (" " | string.NonEmpty) == " ",
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_conversions.ncl b/core/tests/integration/inputs/stdlib/string_conversions.ncl
index 694384d71e..76dabfcd33 100644
--- a/core/tests/integration/inputs/stdlib/string_conversions.ncl
+++ b/core/tests/integration/inputs/stdlib/string_conversions.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -35,4 +35,4 @@ let {string, ..} = std in
   string.to_enum "X" == 'X,
   string.to_enum "X" == string.to_enum "X",
   string.to_enum "タグ" == '"タグ",
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_find.ncl b/core/tests/integration/inputs/stdlib/string_find.ncl
index bef00b6641..2dd0a7a60d 100644
--- a/core/tests/integration/inputs/stdlib/string_find.ncl
+++ b/core/tests/integration/inputs/stdlib/string_find.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let { check, .. } = import "../lib/assert.ncl" in
+
 let { string, .. } = std in
 
 [
@@ -8,4 +8,4 @@ let { string, .. } = std in
   std.string.find "(\\d+)\\.(\\d+)\\.(\\d+)" "1.2.3" == { groups = ["1", "2", "3"], index = 0, matched = "1.2.3" },
   std.string.find "(\\p{Emoji})=(\\w+)" "😀=smiling" == { groups = ["😀", "smiling"], index = 0, matched = "😀=smiling" }
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_find_all.ncl b/core/tests/integration/inputs/stdlib/string_find_all.ncl
index 0a2c563b39..6124548112 100644
--- a/core/tests/integration/inputs/stdlib/string_find_all.ncl
+++ b/core/tests/integration/inputs/stdlib/string_find_all.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let { check, .. } = import "../lib/assert.ncl" in
+
 let { string, .. } = std in
 
 [
@@ -27,4 +27,4 @@ let { string, .. } = std in
     { groups = ["🫠", "melting"], index = 22, matched = "🫠=melting", }
   ]
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_primitives.ncl b/core/tests/integration/inputs/stdlib/string_primitives.ncl
index 8ca7fe42f9..65e6d3b95a 100644
--- a/core/tests/integration/inputs/stdlib/string_primitives.ncl
+++ b/core/tests/integration/inputs/stdlib/string_primitives.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -34,4 +34,4 @@ let {string, ..} = std in
   string.substring 0 1 "👩🏻‍🦲" == "👩🏻‍🦲",
   string.substring 1 6 "👨‍❤️‍💋‍👨hello" == "hello",
   string.substring 2 4 "ab👨‍❤️‍💋‍👨👨‍❤️‍💋‍👨cd" == "👨‍❤️‍💋‍👨👨‍❤️‍💋‍👨",
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_split_join.ncl b/core/tests/integration/inputs/stdlib/string_split_join.ncl
index 93b3381430..574bb3b58d 100644
--- a/core/tests/integration/inputs/stdlib/string_split_join.ncl
+++ b/core/tests/integration/inputs/stdlib/string_split_join.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -31,4 +31,4 @@ let {string, ..} = std in
     { sep = " ", str = "this is a sentence."},
     { sep = "👩‍❤️‍💋‍👨", str = "-👩‍❤️‍💋‍👨👩‍❤️‍💋‍👨👩‍❤️‍💋‍👨-" },
   ],
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_trim.ncl b/core/tests/integration/inputs/stdlib/string_trim.ncl
index b817b58e26..025f752e1c 100644
--- a/core/tests/integration/inputs/stdlib/string_trim.ncl
+++ b/core/tests/integration/inputs/stdlib/string_trim.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -19,4 +19,4 @@ let {string, ..} = std in
 
 
   "% == "a multiline string",
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/stdlib/string_uppercase_lowercase.ncl b/core/tests/integration/inputs/stdlib/string_uppercase_lowercase.ncl
index b2f502102f..231ba5dc8b 100644
--- a/core/tests/integration/inputs/stdlib/string_uppercase_lowercase.ncl
+++ b/core/tests/integration/inputs/stdlib/string_uppercase_lowercase.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let {string, ..} = std in
 
 [
@@ -32,4 +32,4 @@ let {string, ..} = std in
     "XXXXYYYYZZZZ",
     "THIS IS A TEST"
   ],
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/strings/string_interpolation.ncl b/core/tests/integration/inputs/strings/string_interpolation.ncl
index b9f4f3ba10..24896e2058 100644
--- a/core/tests/integration/inputs/strings/string_interpolation.ncl
+++ b/core/tests/integration/inputs/strings/string_interpolation.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 
 [
   # Simple interpolation tests
@@ -54,4 +54,4 @@ let {check, ..} = import "../lib/assert.ncl" in
   let actual = m%%"XYZ "%%%{"CBA"}""%% in
   let expected = "XYZ \"%CBA\"" in
   actual == expected,
-] |> check
+] |> std.test.assert_all
diff --git a/core/tests/integration/inputs/strings/symbolic_strings.ncl b/core/tests/integration/inputs/strings/symbolic_strings.ncl
index 7bf7c4e13e..4ab7727cdb 100644
--- a/core/tests/integration/inputs/strings/symbolic_strings.ncl
+++ b/core/tests/integration/inputs/strings/symbolic_strings.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {check, ..} = import "../lib/assert.ncl" in
+
 let sym = fun prefix_ fragments_ => { tag = 'SymbolicString, prefix = prefix_, fragments = fragments_ } in
 
 [
@@ -43,4 +43,4 @@ let sym = fun prefix_ fragments_ => { tag = 'SymbolicString, prefix = prefix_, f
   in
   actual == expected,
 ]
-|> check
+|> std.test.assert_all
diff --git a/core/tests/integration/inputs/typecheck/basic_typechecking.ncl b/core/tests/integration/inputs/typecheck/basic_typechecking.ncl
index 83c48cfbfc..ae5d6d7ce9 100644
--- a/core/tests/integration/inputs/typecheck/basic_typechecking.ncl
+++ b/core/tests/integration/inputs/typecheck/basic_typechecking.ncl
@@ -1,5 +1,5 @@
 # test.type = 'pass'
-let {Assert, ..} = import "../lib/assert.ncl" in
+let Assert = std.test.Assert in
 
 (let plus : Number -> Number -> Number = fun x => fun y => x + y in
  plus (54 : Number) (6 : Number) == 60 | Assert)
diff --git a/flake.lock b/flake.lock
index 50d0fb8f5f..915dc22722 100644
--- a/flake.lock
+++ b/flake.lock
@@ -3,11 +3,11 @@
     "advisory-db": {
       "flake": false,
       "locked": {
-        "lastModified": 1712168594,
-        "narHash": "sha256-1Yh+vafNq19JDfmpknkWq11AkcQLPmFZ8X6YJZT5r7o=",
+        "lastModified": 1714183630,
+        "narHash": "sha256-1BVft7ggSN2XXFeXQjazU3jN9wVECd9qp2mZx/8GDMk=",
         "owner": "rustsec",
         "repo": "advisory-db",
-        "rev": "0bc9a77248be5cb5f2b51fe6aba8ba451d74c6bb",
+        "rev": "35e7459a331d3e0c585e56dabd03006b9b354088",
         "type": "github"
       },
       "original": {
@@ -23,11 +23,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1715274763,
-        "narHash": "sha256-3Iv1PGHJn9sV3HO4FlOVaaztOxa9uGLfOmUWrH7v7+A=",
+        "lastModified": 1716156051,
+        "narHash": "sha256-TjUX7WWRcrhuUxDHsR8pDR2N7jitqZehgCVSy3kBeS8=",
         "owner": "ipetkov",
         "repo": "crane",
-        "rev": "27025ab71bdca30e7ed0a16c88fd74c5970fc7f5",
+        "rev": "7443df1c478947bf96a2e699209f53b2db26209d",
         "type": "github"
       },
       "original": {
@@ -44,11 +44,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1712180168,
-        "narHash": "sha256-sYe00cK+kKnQlVo1wUIZ5rZl9x8/r3djShUqNgfjnM4=",
+        "lastModified": 1715274763,
+        "narHash": "sha256-3Iv1PGHJn9sV3HO4FlOVaaztOxa9uGLfOmUWrH7v7+A=",
         "owner": "ipetkov",
         "repo": "crane",
-        "rev": "06a9ff255c1681299a87191c2725d9d579f28b82",
+        "rev": "27025ab71bdca30e7ed0a16c88fd74c5970fc7f5",
         "type": "github"
       },
       "original": {
@@ -241,11 +241,11 @@
         "pre-commit-hooks": "pre-commit-hooks"
       },
       "locked": {
-        "lastModified": 1715361977,
-        "narHash": "sha256-j/PLYYGs+Gjge4JGYxMjOhWQEp+GB4Fdicetbpmp6n0=",
+        "lastModified": 1716186515,
+        "narHash": "sha256-BSvldBxypiYGuVuYfrIZNoM+tlkDsgQdz9HKe9e57v8=",
         "owner": "nixos",
         "repo": "nix",
-        "rev": "87ab3c0ea4e6f85e7b902050365bb75cf2836fbb",
+        "rev": "209d75529caaaf82a760056fc60156b9153af5c8",
         "type": "github"
       },
       "original": {
@@ -304,11 +304,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1715787315,
-        "narHash": "sha256-cYApT0NXJfqBkKcci7D9Kr4CBYZKOQKDYA23q8XNuWg=",
+        "lastModified": 1715961556,
+        "narHash": "sha256-+NpbZRCRisUHKQJZF3CT+xn14ZZQO+KjxIIanH3Pvn4=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "33d1e753c82ffc557b4a585c77de43d4c922ebb5",
+        "rev": "4a6b83b05df1a8bd7d99095ec4b4d271f2956b64",
         "type": "github"
       },
       "original": {
@@ -409,11 +409,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1715393623,
-        "narHash": "sha256-nSUFcUqyTQQ/aYFIB05mpCzytcKvfKMy3ZQAe0fP26A=",
+        "lastModified": 1716171463,
+        "narHash": "sha256-lc7wOh5BjYUoxdhcPkeUY8BmuL2qtRaHlW1403RW48E=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "8eb8671512cb0c72c748058506e50c54fb5d8e2b",
+        "rev": "04d61d14803854fd8453ec43c5c53a471e5407a8",
         "type": "github"
       },
       "original": {
@@ -428,11 +428,11 @@
         "nixpkgs": "nixpkgs_3"
       },
       "locked": {
-        "lastModified": 1712196778,
-        "narHash": "sha256-SOiwCr2HtmYpw8OvQQVRPtiCBWwndbIoPqtsamZK3J8=",
+        "lastModified": 1715739484,
+        "narHash": "sha256-5zlSuCM54jH6tXi8OILZ7opT+lBYUkGU9eOMEvJh9HU=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "20e7895d1873cc64c14a9f024a8e04f5824bed28",
+        "rev": "3d27c65641a61d36f1c7616d6150524cd9a2a5f7",
         "type": "github"
       },
       "original": {
@@ -498,11 +498,11 @@
         "rust-overlay": "rust-overlay_2"
       },
       "locked": {
-        "lastModified": 1712658781,
-        "narHash": "sha256-KWfgbVFV2zbCuNNFp9yeSgAa0Cc7cT090KK2J1ynfKg=",
+        "lastModified": 1715781565,
+        "narHash": "sha256-5o5DvwUYAmODYlFCuDJwRvEkitgq2SFD9Wy0DRMjKsY=",
         "owner": "tweag",
         "repo": "topiary",
-        "rev": "82a94a9f57104b89d4316afaeeab271cc51f7698",
+        "rev": "ba4f44062299cfc45d3c383e9697c325bedd0078",
         "type": "github"
       },
       "original": {