add test circuits, some minor fixes, array tests

.gitignore

@@ -1,5 +1,5 @@
 node_modules
-circuits/test
-circuits/main
+# circuits/test # keep the test files
+# circuits/main # keep the main files
 build
 .yarn

README.md

@@ -54,8 +54,10 @@ The tests make use of [Circomkit](https://github.com/erhant/circomkit).
 
 ## Style
 
-Check the formatting of test codes using:
+Check the formatting with the following command:
 
 ```sh
 yarn format
 ```
+
+This command checks the test code with [Prettier](https://www.npmjs.com/package/prettier), and lints the book with [Markdownlint](https://www.npmjs.com/package/markdownlint).

book/src/arrays/README.md

@@ -5,7 +5,7 @@ Circom arrays are a different kind of beast. The main reason is that in Circom,
 - Array sizes are fixed, e.g. you can't define an array based on the user input after compiling the circuit.
 - Array indexing should be known at compile time, e.g. you can't ask a user for index `i` and return `arr[i]` like you _normally_ do.
 
-Before we get to the problematic unknown-at-compile-time stuff, let's quickly recap the known-time array operations:
+Before we get to the problematic unknown-at-compile-time stuff, let's quickly recap the known-at-compile-time array operations:
 
 ```cs
 // an array with N elements
@@ -17,7 +17,7 @@ signal arr[N][M];
 // read element at index i for known i
 foo <== arr[i];
 
-// write to element at index j for known i
+// write to element at index j for known j
 arr[j] <== bar;
 ```
 

book/src/control-flow/README.md

@@ -97,7 +97,7 @@ It is often useful to switch the places of two signals based on a condition, whi
 >   signal input in[2];
 >   signal output out[2];
 >
->   aux <== (in[1] - in[0]) * cond;
+>   signal aux <== (in[1] - in[0]) * cond;
 >
 >   out[0] <==  aux + in[0];
 >   out[1] <== -aux + in[1];

book/src/merkle-trees/README.md

@@ -1,6 +1,6 @@
 # Merkle Trees
 
-If you have been in the world of crypto for a while, it is highly likely that you have heard the term [Merkle Tree](https://brilliant.org/wiki/merkle-tree/), also known as Merkle Hash Tree. A Merkle Tree is a hash-based data structure, an can serve as a cryptographic commitment scheme.
+If you have been in the world of crypto for a while, it is highly likely that you have heard the term [Merkle Tree](https://brilliant.org/wiki/merkle-tree/), also known as Merkle Hash Tree. A Merkle Tree is a hash-based data structure, and can serve as a cryptographic commitment scheme.
 
 You can commit to a set of values using a merkle tree, such as:
 
@@ -40,7 +40,7 @@ In a Merkle Tree, every node is made up of the hash of its children. In this exa
 - $h_3 = H(h_6, h_7)$
 - and so on.
 
-The leaf nodes are the hashes of elements of the committed set of data. The final hash $h1$ at the root of the tree is called the **Merkle Root**.
+The leaf nodes are the hashes of elements of the committed set of data. The final hash $h_1$ at the root of the tree is called the **Merkle Root**.
 
 > Merkle Trees are often implemented as binary trees, but the concept works for $n$-ary trees as well, where each node has $n$ children.
 
@@ -90,13 +90,6 @@ graph BT
 
 You see, we only needed to provide 3 hashes here, although our data had 8 elements! In fact, if you have $n$ elements you only need to provide $\log_2{n}$ elements to the verifier, this is so much more efficient than the naive method of sending all the data to the verifier.
 
-- The root is the **commitment** to the vector.
-- The **reveal** a value in the commitment (which is a leaf in the tree) prover does the following:
-  - Send sibling hashes of all nodes on root-to-leaf path.
-  - Verifier checks if the hashes are consistent with the root hash.
-  - The size of this proof to reveal a value is $\mathcal{O}(\log n)$ hash values.
-- This is a **binding** scheme: once the root hash is sent, the committer is bound to the committed vector. Opening any leaf to two different values requires finding a hash collision, assumed to be intractable.
-
 ## As a Commitment Scheme
 
 A Merkle Root can serve as a cryptographic **commitment** to a set of data.

circuits/basics/magic.circom

@@ -7,21 +7,19 @@ pragma circom 2.1.0;
 //
 // Inputs:
 // - in: an N-by-N square
-//
-// Outputs:
-// - sum: the magic sum
+// - sum (public): the magic sum
 template MagicSquare(n) {
   signal input in[n][n];
-  signal output sum;
+  signal input sum;
 
   // sum diagonals
   var diags[2];
   for (var d = 0; d < n; d++) {
     diags[0] += in[d][d];     // top-left -> bottom-right
     diags[1] += in[n-1-d][d]; // bottom-left -> top-right
   }
-  sum <== diags[0]; // assign this one
-  sum === diags[1]; // check others with equality
+  sum === diags[0];
+  sum === diags[1];
 
   // sum rows
   var rowsums[n];
@@ -40,6 +38,4 @@ template MagicSquare(n) {
     }
     sum === colsums[j];
   }
-
-  // TODO: complete circuit
 }

circuits/test/arrays/arr_read_10.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../arrays/index.circom";
+
+component main = ArrayRead(10);

circuits/test/arrays/arr_sum_10.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../arrays/index.circom";
+
+component main = Sum(10);

circuits/test/arrays/distinct_3.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../arrays/distinct.circom";
+
+component main = AssertDistinct(3);

circuits/test/arrays/is_distinct_3.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../arrays/distinct.circom";
+
+component main = IsDistinct(3);

circuits/test/basics/fibonacci_14.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../basics/fibonacci.circom";
+
+component main = Fibonacci(14);

circuits/test/basics/magic_3x3.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../basics/magic.circom";
+
+component main {public[sum]} = MagicSquare(3);

circuits/test/basics/magic_4x4.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../basics/magic.circom";
+
+component main {public[sum]} = MagicSquare(4);

circuits/test/basics/multiplier_3.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../basics/multiplier.circom";
+
+component main = Multiplier(3);

circuits/test/basics/sudoku_4x4.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../basics/sudoku.circom";
+
+component main {public[puzzle]} = Sudoku(2);

circuits/test/basics/sudoku_9x9.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../basics/sudoku.circom";
+
+component main {public[puzzle]} = Sudoku(3);

circuits/test/bits/and_gate.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../bits/gates.circom";
+
+component main = AND();

circuits/test/bits/bits2num_5.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../bits/index.circom";
+
+component main = Bits2Num(5);

circuits/test/bits/not_gate.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../bits/gates.circom";
+
+component main = NOT();

circuits/test/bits/num2bits_5.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../bits/index.circom";
+
+component main = Num2Bits(5);

circuits/test/bits/or_gate.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../bits/gates.circom";
+
+component main = OR();

circuits/test/bits/xor_gate.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../bits/gates.circom";
+
+component main = XOR();

circuits/test/comparators/compconstant.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../comparators/compconstant.circom";
+
+component main = CompConstant(6896);

circuits/test/comparators/ifelse.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../comparators/index.circom";
+
+component main = IfElse();

circuits/test/comparators/inRange_1_9.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../comparators/range.circom";
+
+component main = AssertInRange(1, 9);

circuits/test/comparators/switch.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../comparators/index.circom";
+
+component main = Switch();

circuits/test/control-flow/ifelse.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../control-flow/index.circom";
+
+component main = IfElse();

circuits/test/control-flow/switch.circom

@@ -0,0 +1,6 @@
+// auto-generated by circomkit
+pragma circom 2.0.0;
+
+include "../../control-flow/index.circom";
+
+component main = Switch();

package.json

@@ -4,7 +4,9 @@
   "license": "MIT",
   "scripts": {
     "test": "npx jest",
-    "format": "npx prettier --check ./tests/**/*.ts",
+    "format": "yarn format:ts",
+    "format:ts": "npx prettier --check ./tests/**/*.ts",
+    "format:md": "echo todo",
     "book": "cd book && mdbook serve --open",
     "book:build": "cd book && mdbook build"
   },
@@ -16,6 +18,7 @@
     "@types/jest": "^29.5.12",
     "@types/node": "^20.11.16",
     "jest": "^29.7.0",
+    "markdownlint": "^0.33.0",
     "prettier": "^3.2.5",
     "ts-jest": "^29.1.2",
     "ts-node": "^10.9.1",

tests/arrays/index.test.ts

@@ -1,6 +1,77 @@
 import type { WitnessTester } from "circomkit";
-import { circomkit } from "../common";
+import { circomkit, primes } from "../common";
 
-describe.skip("arrays", () => {
-  // TODO
+describe("arrays", () => {
+  const N = 10;
+  const arr = Array.from({ length: N }, (_, i) => i);
+
+  describe("reads", () => {
+    let circuit: WitnessTester<["in", "index"], ["out"]>;
+
+    beforeAll(async () => {
+      circuit = await circomkit.WitnessTester(`arr_read_${N}`, {
+        file: "arrays/index",
+        template: "ArrayRead",
+        dir: "test/arrays",
+        params: [N],
+      });
+    });
+
+    it("should read correct index", async () => {
+      for (let i = 0; i < N; i += N >> 2) {
+        await circuit.expectPass({ in: arr, index: i }, { out: arr[i] });
+      }
+    });
+
+    it("should read 0 for out-of-bounds index", async () => {
+      await circuit.expectPass({ in: arr, index: N }, { out: 0 });
+      await circuit.expectPass({ in: arr, index: -1 }, { out: 0 });
+    });
+  });
+
+  describe("writes", () => {
+    let circuit: WitnessTester<["in", "index", "value"], ["out"]>;
+
+    beforeAll(async () => {
+      circuit = await circomkit.WitnessTester(`arr_sum_${N}`, {
+        file: "arrays/index",
+        template: "ArrayWrite",
+        dir: "test/arrays",
+        params: [N],
+      });
+    });
+
+    it("should write correctly", async () => {
+      for (let i = 0; i < N; i += N >> 2) {
+        const newArr = [...arr];
+        const val = i * 10;
+        newArr[i] = val;
+        await circuit.expectPass({ in: arr, index: i, value: val }, { out: newArr });
+      }
+    });
+
+    it("should return the same array for out-of-bounds index", async () => {
+      await circuit.expectPass({ in: arr, index: N, value: -1 }, { out: arr });
+      await circuit.expectPass({ in: arr, index: -1, value: -1 }, { out: arr });
+    });
+  });
+
+  describe("sum", () => {
+    let circuit: WitnessTester<["in"], ["out"]>;
+
+    beforeAll(async () => {
+      circuit = await circomkit.WitnessTester(`arr_sum_${N}`, {
+        file: "arrays/index",
+        template: "Sum",
+        dir: "test/arrays",
+        params: [N],
+      });
+    });
+
+    it("should sum correctly", async () => {
+      // NOTE: may give wrong results for large N, use modulo if you have to
+      const sum = arr.reduce((acc, cur) => acc + cur);
+      await circuit.expectPass({ in: arr }, { out: sum });
+    });
+  });
 });