mujoco/wasm/tests/bindings_test.ts at main · CodeLine9/mujoco · GitHub

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// Copyright 2025 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import 'jasmine';

import {MainModule, MjContact, MjContactVec, MjData, MjLROpt, MjModel,
MjOption, MjsGeom, MjSolverStat, MjSpec, MjStatistic, MjTimerStat, MjvCamera,
MjvFigure, MjvGeom, MjvGLCamera, MjvLight, MjvOption, MjvPerturb, MjvScene,
MjWarningStat, MjVFS, Uint8Buffer} from '../dist/mujoco.js';

import loadMujoco from '../dist/mujoco.js'

function assertExists<T>(value: T | null | undefined, message?: string):
asserts value is T {
  if (value === null || value === undefined) {
    throw new Error(message ?? 'Expected value to be defined.');
  }
}


// Corresponds to bindings_test.py:TEST_XML
const TEST_XML = `
<mujoco model="test">
  <compiler coordinate="local" angle="radian" eulerseq="xyz"/>
  <size nkey="2"/>
  <option timestep="0.002" gravity="0 0 -9.81"/>
  <visual>
    <global fovy="50" />
    <quality shadowsize="51" />
  </visual>
  <worldbody>
    <geom name="myplane" type="plane" size="10 10 1" user="1 2 3"/>
    <body name="mybox" pos="0 0 0.1">
      <geom name="mybox" type="box" size="0.1 0.1 0.1" mass="0.25"/>
      <freejoint name="myfree"/>
    </body>
    <body name="myhinge-body" pos="0 0 1">
      <inertial pos="0 0 0" mass="1" diaginertia="1 1 1"/>
      <site pos="0 0 -1" name="mysite" type="sphere"/>
      <joint name="myhinge" type="hinge" axis="0 1 0" damping="1"/>
    </body>
    <body name="myball-body" pos="2 0 1">
      <inertial pos="0 0 0" mass="1" diaginertia="1 1 1"/>
      <joint name="myball" type="ball"/>
    </body>
    <body name="mocap-body" mocap="true" pos="42 0 42">
      <geom name="mocap-sphere" type="sphere" size="0.1"/>
    </body>
  </worldbody>
  <actuator>
    <position name="myactuator" joint="myhinge"/>
  </actuator>
  <sensor>
    <jointvel name="myjointvel" joint="myhinge"/>
    <accelerometer name="myaccelerometer" site="mysite"/>
  </sensor>
</mujoco>
`;

type TypedArray =|Int8Array|Uint8Array|Uint8ClampedArray|Int16Array|Uint16Array|
    Int32Array|Uint32Array|Float32Array|Float64Array;

function norm(arr: number[]): number {
  return Math.sqrt(arr.reduce((acc, val) => acc + val * val, 0));
}

function expectArraysClose(arr1: any, arr2: TypedArray, precision = 1) {
  expect(arr1.length).toEqual(arr2.length);
  for (let i = 0; i < arr1.length; i++) {
    expect(arr1[i]).toBeCloseTo(arr2[i], precision);
  }
}

function expectArraysEqual(arr1: any, arr2: TypedArray) {
  expect(arr1.length).toEqual(arr2.length);
  for (let i = 0; i < arr1.length; i++) {
    expect(arr1[i]).toEqual(arr2[i]);
  }
}

describe('MuJoCo WASM Bindings', () => {
  let mujoco: MainModule;
  let model: MjModel|null = null;
  let data: MjData|null = null;

  beforeAll(async () => {
    mujoco = await loadMujoco();
  });

  function unlinkXMLFile(filename: string) {
    try {
      (mujoco as any).FS.unlink(filename);
    } catch (e) {
      console.warn(`Failed to unlink temporary XML file: ${e}`);
    }
  }

  function writeXMLFile(filename: string, xmlContent: string) {
    try {
      (mujoco as any).FS.writeFile(filename, xmlContent);
    } catch (e) {
      throw new Error(`Failed to write temporary XML file: ${e}`);
    }
  }

  beforeEach(() => {
    const tempXmlFilename = '/tmp/model.xml';

    writeXMLFile(tempXmlFilename, TEST_XML);

    model = mujoco.MjModel!.mj_loadXML(tempXmlFilename);
    if (!model) {
      unlinkXMLFile(tempXmlFilename);
      throw new Error('Failed to load model from XML');
    }

    unlinkXMLFile(tempXmlFilename);

    data = new mujoco.MjData(model);
    if (!data) {
      throw new Error('Failed to create data from model');
    }
  });

  afterEach(() => {
    model?.delete();
    data?.delete();
  });

  describe('Buffer API', () => {
    it('should construct from an element count', () => {
      const buf = new mujoco.DoubleBuffer(5);
      expect(buf.GetElementCount()).toBe(5);
      expect(buf.GetPointer()).toBeDefined();
      expect(buf.GetView()).toBeDefined();
    });

    it('should construct from a Javascript array', () => {
      const array: number[] = [0, 1, 4, 9, 16];
      const buf = mujoco.DoubleBuffer.FromArray(array);
      expect(buf.GetElementCount()).toBe(5);
      expect(buf.GetPointer()).toBeDefined();
      expect(buf.GetView()).toBeDefined();
      expectArraysClose(buf.GetView(), new Float64Array(array));
    });

    it('should construct from Float64Array', () => {
      const array = new Float64Array([1 / 11, 7 / 11]);
      const buf = mujoco.DoubleBuffer.FromArray(array);
      expect(buf.GetElementCount()).toBe(2);
      expect(buf.GetPointer()).toBeDefined();
      expect(buf.GetView()).toBeDefined();
      expectArraysClose(buf.GetView(), array);
    });
  });

  describe('mj_addM', () => {
    let simpleModel: MjModel|null = null;
    let simpleData: MjData|null = null;
    const tempXmlFilename = '/tmp/simple_model.xml';
    // A simpler model with nv=1 and nM=1 to avoid WASM binding bugs.
    const simpleXmlContent = `
<mujoco>
  <worldbody>
    <body name="box" pos="0 0 0.5">
      <joint type="slide" axis="1 0 0"/>
      <geom type="box" size="0.1 0.1 0.1" mass="1"/>
    </body>
  </worldbody>
</mujoco>`;

    beforeEach(() => {
      writeXMLFile(tempXmlFilename, simpleXmlContent);
      simpleModel = mujoco.MjModel!.mj_loadXML(tempXmlFilename);
      assertExists(simpleModel);
      simpleData = new mujoco.MjData(simpleModel);
      assertExists(simpleData);
    });

    afterEach(() => {
      simpleModel?.delete();
      simpleData?.delete();
      unlinkXMLFile(tempXmlFilename);
    });

    it('should compute the sparse inertia matrix', () => {
      const nM = simpleModel!.nM;
      const dstSparse = new mujoco.DoubleBuffer(nM);
      try {
        mujoco.mj_forward(simpleModel!, simpleData!);
        mujoco.mj_addM(
            simpleModel!, simpleData!, dstSparse, simpleModel!.M_rownnz,
            simpleModel!.M_rowadr, simpleModel!.M_colind);

        expect(dstSparse.GetView().length).toBe(1);
        expect(dstSparse.GetView()[0]).toBeCloseTo(1.0);
      } finally {
        dstSparse.delete();
      }
    });

    it('should throw an error for incorrect sparse matrix dimensions', () => {
      const nM = simpleModel!.nM;
      const dstSparse = new mujoco.DoubleBuffer(nM + 1);
      try {
        expect(
            () => mujoco.mj_addM(
                simpleModel!, simpleData!, dstSparse, simpleModel!.M_rownnz,
                simpleModel!.M_rowadr, simpleModel!.M_colind))
            .toThrowError(
                'MuJoCo Error: [mj_addM] dst must have size 1, got 2');
      } finally {
        dstSparse.delete();
      }
    });

    it('should compute the sparse inertia matrix with null pointers', () => {
      const nM = simpleModel!.nM;
      const dstSparse = new mujoco.DoubleBuffer(nM);
      try {
        mujoco.mj_forward(simpleModel!, simpleData!);
        mujoco.mj_addM(simpleModel!, simpleData!, dstSparse, null, null, null);

        expect(dstSparse.GetView().length).toBe(1);
      } finally {
        dstSparse.delete();
      }
    });
  });

  it('should compute geom distance without returning fromto', () => {
    mujoco.mj_forward(model!, data!);
    const dist = mujoco.mj_geomDistance(model!, data!, 0, 2, 200, null);
    expect(dist).toEqual(41.9);
  });

  it('should handle box QP solver with null optionals', () => {
    const n = 5;
    const res = new mujoco.DoubleBuffer(n);
    const r = new mujoco.DoubleBuffer(n * (n + 7));
    const h = new mujoco.DoubleBuffer(n * n);
    const g = mujoco.DoubleBuffer.FromArray(new Array(n).fill(1));
    try {
      for (let i = 0; i < n; i++) {
        h.GetView()[i * (n + 1)] = 1;
      }
      const rank = mujoco.mju_boxQP(
          res, r, null, h.GetView(), g.GetView(), null as any, null as any);
      expect(rank).toBeGreaterThan(-1);
    } finally {
      res.delete();
      r.delete();
      h.delete();
      g.delete();
    }
  });

  // Corresponds to engine_core_constraint_test.cc:TEST_F(CoreConstraintTest,
  // ConstraintUpdateImpl)
  it('should correctly compute constraint cost', () => {
    const xmlString = `
<mujoco>
  <option>
    <flag island="enable"/>
  </option>

  <default>
    <geom size=".1"/>
  </default>

  <visual>
    <headlight diffuse=".9 .9 .9"/>
  </visual>

  <worldbody>

    <body>
      <joint type="slide" axis="0 0 1" range="0 1" limited="true"/>
      <geom/>
    </body>

    <body pos=".25 0 0">
      <joint type="slide" axis="1 0 0"/>
      <geom/>
    </body>

    <body pos="0 0 0.25">
      <joint type="slide" axis="0 0 1"/>
      <geom/>
      <body pos="0 -.15 0">
        <joint name="hinge1" axis="0 1 0"/>
        <geom type="capsule" size="0.03" fromto="0 0 0 -.2 0 0"/>
        <body pos="-.2 0 0">
          <joint axis="0 1 0"/>
          <geom type="capsule" size="0.03" fromto="0 0 0 -.2 0 0"/>
        </body>
      </body>
    </body>

    <body pos=".5 0 0">
      <joint type="slide" axis="0 0 1" frictionloss="15"/>
      <geom type="box" size=".08 .08 .02" euler="0 10 0"/>
    </body>

    <body pos="-.5 0 0">
      <joint axis="0 1 0" frictionloss=".01"/>
      <geom type="capsule" size="0.03" fromto="0 0 0 -.2 0 0"/>
    </body>

    <body pos="0 0 .5">
      <joint name="hinge2" axis="0 1 0"/>
      <geom type="box" size=".08 .02 .08"/>
    </body>

    <body pos=".5 0 .1">
      <freejoint/>
      <geom type="box" size=".03 .03 .03" pos="0.01 0.01 0.01"/>
    </body>

    <site name="0" pos="-.45 -.05 .35"/>
    <body pos="-.5 0 .3" name="connect">
      <freejoint/>
      <geom type="box" size=".05 .05 .05"/>
      <site name="1" pos=".05 -.05 .05"/>
    </body>
  </worldbody>

  <equality>
    <joint joint1="hinge1" joint2="hinge2"/>
    <connect body1="connect" body2="world" anchor="-.05 -.05 .05"/>
    <connect site1="0" site2="1"/>
  </equality>
</mujoco>
    `;
    const tempXmlFilename = '/tmp/model_c.xml';
    writeXMLFile(tempXmlFilename, xmlString);
    const model = mujoco.MjModel!.mj_loadXML(tempXmlFilename);
    expect(model).not.toBeNull();
    const data = new mujoco.MjData(model!);
    expect(data).not.toBeNull();
    unlinkXMLFile(tempXmlFilename);
    try {
      mujoco.mj_resetData(model, data!);
      let steps = 0;
      while (data!.ncon === 0 && steps < 100) {
        mujoco.mj_step(model!, data!);
        steps++;
      }
      mujoco.mj_forward(model!, data!);
      const res = new mujoco.DoubleBuffer(data!.nefc);
      mujoco.mj_mulJacVec(model!, data!, res, data!.qacc);
      mujoco.mju_subFrom(res, data!.efc_aref);
      const cost = mujoco.DoubleBuffer.FromArray([0]);
      mujoco.mj_constraintUpdate(
          model!, data!, res.GetView(), cost, /*flg_coneHessian=*/ 1);

      expect(cost.GetView()[0]).toBeCloseTo(3357.584);

      res.delete();
      cost.delete();
    } finally {
      data!.delete();
      model!.delete();
    }
  });

  it('should compute body jacobian', () => {
    mujoco.mj_forward(model!, data!);
    const bodyId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_BODY.value, 'mybox');
    const point = [0.1, 0.2, 0.3];
    const jacp = new mujoco.DoubleBuffer(3 * model!.nv);
    const jacr = new mujoco.DoubleBuffer(3 * model!.nv);
    try {
      mujoco.mj_jac(model!, data!, jacp, jacr, point, bodyId);
      expect(norm(jacp.GetView())).toBeGreaterThan(0);
      expect(norm(jacr.GetView())).toBeGreaterThan(0);
      expect(() => mujoco.mj_jac(model!, data!, null, null, point, bodyId))
          .not.toThrow();
    } finally {
      jacp.delete();
      jacr.delete();
    }
  });

  it('should compute body frame jacobian', () => {
    mujoco.mj_forward(model!, data!);
    const bodyId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_BODY.value, 'mybox');
    const jacp = new mujoco.DoubleBuffer(3 * model!.nv);
    const jacr = new mujoco.DoubleBuffer(3 * model!.nv);
    try {
      mujoco.mj_jacBody(model!, data!, jacp, jacr, bodyId);
      expect(norm(jacp.GetView())).toBeGreaterThan(0);
      expect(norm(jacr.GetView())).toBeGreaterThan(0);
      expect(() => mujoco.mj_jacBody(model!, data!, null, null, bodyId))
          .not.toThrow();
    } finally {
      jacp.delete();
      jacr.delete();
    }
  });

  it('should compute body CoM jacobian', () => {
    mujoco.mj_forward(model!, data!);
    const bodyId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_BODY.value, 'mybox');
    const jacp = new mujoco.DoubleBuffer(3 * model!.nv);
    const jacr = new mujoco.DoubleBuffer(3 * model!.nv);
    try {
      mujoco.mj_jacBodyCom(model!, data!, jacp, jacr, bodyId);
      expect(norm(jacp.GetView())).toBeGreaterThan(0);
      expect(norm(jacr.GetView())).toBeGreaterThan(0);
      expect(() => mujoco.mj_jacBodyCom(model!, data!, null, null, bodyId))
          .not.toThrow();
    } finally {
      jacp.delete();
      jacr.delete();
    }
  });

  it('should compute geom jacobian', () => {
    mujoco.mj_forward(model!, data!);
    const geomId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_GEOM.value, 'mybox');
    const jacp = new mujoco.DoubleBuffer(3 * model!.nv);
    const jacr = new mujoco.DoubleBuffer(3 * model!.nv);
    try {
      mujoco.mj_jacGeom(model!, data!, jacp, jacr, geomId);
      expect(norm(jacp.GetView())).toBeGreaterThan(0);
      expect(norm(jacr.GetView())).toBeGreaterThan(0);
      expect(() => mujoco.mj_jacGeom(model!, data!, null, null, geomId))
          .not.toThrow();
    } finally {
      jacp.delete();
      jacr.delete();
    }
  });

  it('should compute point-axis jacobian', () => {
    mujoco.mj_forward(model!, data!);
    const bodyId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_BODY.value, 'mybox');
    const point = [0.1, 0.2, 0.3];
    const axis = [0, 0, 1];
    const jacPoint = new mujoco.DoubleBuffer(3 * model!.nv);
    const jacAxis = new mujoco.DoubleBuffer(3 * model!.nv);
    try {
      mujoco.mj_jacPointAxis(
          model!, data!, jacPoint, jacAxis, point, axis, bodyId);
      expect(norm(jacPoint.GetView())).toBeGreaterThan(0);
      expect(norm(jacAxis.GetView())).toBeGreaterThan(0);
      expect(
          () => mujoco.mj_jacPointAxis(
              model!, data!, null, null, point, axis, bodyId))
          .not.toThrow();
    } finally {
      jacPoint.delete();
      jacAxis.delete();
    }
  });

  it('should compute jacobian time derivative', () => {
    mujoco.mj_forward(model!, data!);
    const bodyId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_BODY.value, 'mybox');
    const point = [0.1, 0.2, 0.3];
    const jacp = new mujoco.DoubleBuffer(3 * model!.nv);
    const jacr = new mujoco.DoubleBuffer(3 * model!.nv);
    try {
      mujoco.mj_jacDot(model!, data!, jacp, jacr, point, bodyId);
      expect(jacp.GetView().length).toBe(3 * model!.nv);
      expect(jacr.GetView().length).toBe(3 * model!.nv);
      expect(() => mujoco.mj_jacDot(model!, data!, null, null, point, bodyId))
          .not.toThrow();
    } finally {
      jacp.delete();
      jacr.delete();
    }
  });

  it('should apply external force and torque', () => {
    const force = [1, .5, 1];
    const torque = [.3, 1, .22];
    const point = [0, 0, 0];
    const bodyId =
        mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_BODY.value, 'mybox');
    const qfrcTarget = new mujoco.DoubleBuffer(model!.nv);
    try {
      mujoco.mj_forward(model!, data!);
      mujoco.mj_applyFT(
          model!, data!, force, torque, point, bodyId, qfrcTarget);
      expect(norm(qfrcTarget.GetView())).toBeGreaterThan(0);

      qfrcTarget.GetView().fill(0);
      mujoco.mj_applyFT(
          model!, data!, null as any, null as any, point, bodyId, qfrcTarget);
      expect(norm(qfrcTarget.GetView())).toEqual(0);
    } finally {
      qfrcTarget.delete();
    }
  });

  it('should compute finite-differenced transition matrices', () => {
    const eps = 1e-6;
    const flg_centered = 0;
    const dim = 2 * model!.nv + model!.na;
    const A = new mujoco.DoubleBuffer(dim * dim);
    const B = new mujoco.DoubleBuffer(dim * model!.nu);
    const C = new mujoco.DoubleBuffer(model!.nsensordata * dim);
    const D = new mujoco.DoubleBuffer(model!.nsensordata * model!.nu);
    try {
      mujoco.mjd_transitionFD(model!, data!, eps, flg_centered, A, B, C, D);
      expect(norm(A.GetView())).toBeGreaterThan(0);
      expect(norm(B.GetView())).toBeGreaterThan(0);
      expect(norm(C.GetView())).toBeGreaterThan(0);
      expect(
          () => mujoco.mjd_transitionFD(
              model!, data!, eps, flg_centered, null, null, null, null))
          .not.toThrow();
    } finally {
      A.delete();
      B.delete();
      C.delete();
      D.delete();
    }
  });

  it('should solve a system of linear equations', () => {
    const n = 2;
    const mat = [4, 1, 1, 3];
    const vec = [1, 2];
    const res = new mujoco.DoubleBuffer(n);
    const expected = new Float64Array([1 / 11, 7 / 11]);
    const matFactor = mujoco.DoubleBuffer.FromArray(mat);
    try {
      const rank = mujoco.mju_cholFactor(matFactor, 1e-9);
      expect(rank).toBe(n);
      mujoco.mju_cholSolve(res, matFactor.GetView(), vec);
      const result = res.GetView();
      expect(result[0]).toBeCloseTo(expected[0]);
      expect(result[1]).toBeCloseTo(expected[1]);
    } finally {
      res.delete();
      matFactor.delete();
    }
  });

  it('should update a Cholesky factorization', () => {
    const n = 2;
    const mat = [4, 1, 1, 3];
    const x = [1, 1];
    const matFactor = mujoco.DoubleBuffer.FromArray(mat);
    const xBuf = mujoco.DoubleBuffer.FromArray(x);
    const res = new mujoco.DoubleBuffer(n);
    try {
      // Factorize original matrix.
      mujoco.mju_cholFactor(matFactor, 1e-9);

      // Update factorization with x.
      const flg_plus = 1;
      mujoco.mju_cholUpdate(matFactor, xBuf.GetView(), flg_plus);

      // Solve a system with the updated factor to verify.
      // A' = A + x*x' = [[5, 2], [2, 4]]
      // A' * y = vec => [[5, 2], [2, 4]] * y = [7, 6]
      // Solution is y = [1, 1].
      const vec = [7, 6];
      mujoco.mju_cholSolve(res, matFactor.GetView(), vec);
      const result = res.GetView();
      const expectedSolution = new Float64Array([1, 1]);
      expect(result[0]).toBeCloseTo(expectedSolution[0]);
      expect(result[1]).toBeCloseTo(expectedSolution[1]);
    } finally {
      matFactor.delete();
      xBuf.delete();
      res.delete();
    }
  });

  it('should multiply a transposed matrix by another matrix', () => {
    const r1 = 3, c1 = 2, c2 = 2;
    const mat1 = mujoco.DoubleBuffer.FromArray([1, 4, 2, 5, 3, 6]);
    const mat2 = mujoco.DoubleBuffer.FromArray([7, 8, 9, 10, 11, 12]);
    const res = new mujoco.DoubleBuffer(c1 * c2);
    const expected = new Float64Array([58, 64, 139, 154]);

    try {
      mujoco.mju_mulMatTMat(res, mat1.GetView(), mat2.GetView(), r1, c1, c2);
      expectArraysClose(res.GetView(), expected);
    } finally {
      mat1.delete();
      mat2.delete();
      res.delete();
    }
  });

  it('should throw an error because of incompatible matrix sizes', () => {
    const r1 = 3, c1 = 2, c2 = 2;
    const mat1 = mujoco.DoubleBuffer.FromArray([1, 4, 2, 5, 3, 6]);
    const mat2 = mujoco.DoubleBuffer.FromArray([7, 8, 9, 10, 11]);
    const res = new mujoco.DoubleBuffer(c1 * c2);
    try {
      expect(
          () => mujoco.mju_mulMatTMat(
              res, mat1.GetView(), mat2.GetView(), r1, c1, c2))
          .toThrowError(
              'MuJoCo Error: [mju_mulMatTMat] mat2 must have size 6, got 5');
    } finally {
      mat1.delete();
      mat2.delete();
      res.delete();
    }
  });

  it('should convert a dense matrix to sparse and return non-zero count',
     () => {
       const nr = 2;
       const nc = 3;
       const mat = [0.0, 1.0, 0.0, 2.0, 0.0, 3.0];
       const rownnz = new mujoco.IntBuffer(nr);
       const rowadr = new mujoco.IntBuffer(nr);
       const colind = new mujoco.IntBuffer(nc);
       const res = new mujoco.DoubleBuffer(nc);
       try {
         const nnz =
             mujoco.mju_dense2sparse(res, mat, nr, nc, rownnz, rowadr, colind);
         expectArraysEqual(res.GetView(), new Float64Array([1.0, 2.0, 3.0]));
         expectArraysEqual(rownnz.GetView(), new Int32Array([1, 2]));
         expectArraysEqual(rowadr.GetView(), new Int32Array([0, 1]));
         expectArraysEqual(colind.GetView(), new Int32Array([1, 0, 2]));
       } finally {
         res.delete();
         rownnz.delete();
         rowadr.delete();
         colind.delete();
       }
     });

  it('should convert a sparse matrix to a dense matrix', () => {
    const nr = 2;
    const nc = 3;
    const mat = [1.0, 2.0, 3.0];
    const rownnz = [1, 2];
    const rowadr = [0, 1];
    const colind = [1, 0, 2];
    const res = new mujoco.DoubleBuffer(nr * nc);
    const expected = new Float64Array([0.0, 1.0, 0.0, 2.0, 0.0, 3.0]);
    try {
      mujoco.mju_sparse2dense(res, mat, nr, nc, rownnz, rowadr, colind);
      expectArraysEqual(res.GetView(), expected);
    } finally {
      res.delete();
    }
  });

  it('should throw an error when mju_eye is called with a null argument', () => {
    expect(() => {
      mujoco.mju_eye(null as any);
    })
        .toThrowError(
            'MuJoCo Error: [mju_eye] Invalid argument. Expected a TypedArray or WasmBuffer, got null.');
  });

  it('should return undefined', () => {
    const spec = mujoco.parseXMLString(TEST_XML);
    const body = mujoco.mjs_findBody(spec, 'some_name_that_doesnt_exist');
    expect(body).toBeUndefined();
    body?.delete();
    spec?.delete();
  });

  it('should check constants values', () => {
    expect(mujoco.mjNEQDATA).toBe(11);
    expect(mujoco.mjDISABLESTRING).toEqual([
      'Constraint', 'Equality', 'Frictionloss', 'Limit', 'Contact', 'Spring',
      'Damper', 'Gravity', 'Clampctrl', 'Warmstart', 'Filterparent',
      'Actuation', 'Refsafe', 'Sensor', 'Midphase', 'Eulerdamp', 'AutoReset',
      'NativeCCD', 'Island'
    ]);
    expect(mujoco.mjRNDSTRING).toEqual([
      ['Shadow', '1', 'S'], ['Wireframe', '0', 'W'], ['Reflection', '1', 'R'],
      ['Additive', '0', 'L'], ['Skybox', '1', 'K'], ['Fog', '0', 'G'],
      ['Haze', '1', '/'], ['Depth', '0', ''], ['Segment', '0', ','],
      ['Id Color', '0', ''], ['Cull Face', '1', '']
    ]);
    expect(mujoco.mjFRAMESTRING.length).toEqual(mujoco.mjtFrame.mjNFRAME.value);
    expect(mujoco.mjVISSTRING.length)
        .toEqual(mujoco.mjtVisFlag.mjNVISFLAG.value);
    expect(mujoco.mjVISSTRING[mujoco.mjtVisFlag.mjVIS_INERTIA.value]).toEqual([
      'Inertia', '0', 'I'
    ]);
  });

  it('should create a spec from XML', () => {
    const spec = mujoco.parseXMLString(TEST_XML);
    try {
      expect(spec).toBeDefined();
      expect(spec!.modelname).toEqual('test');
    } finally {
      spec?.delete();
    }
  });

  it('should return the max value', () => {
    expect(mujoco.mju_max(10, 2)).toEqual(10);
  });

  // Corresponds to bindings_test.py:test_mju_rotVecQuat
  it('should rotate a vector by a quaternion', () => {
    const res = mujoco.DoubleBuffer.FromArray([0, 0, 0]);
    const vec = [1, 0, 0];
    const angle = 7 * Math.PI / 12;
    const quat = [Math.cos(angle), 0, 0, Math.sin(angle)];
    const expected = new Float64Array([-0.8660377, -0.5, 0]);
    try {
      mujoco.mju_rotVecQuat(res, vec, quat);
      expectArraysClose(res.GetView(), expected, 4);
    } finally {
      res.delete();
    }
  });

  it('should get correct geom name', () => {
    const spec = mujoco.parseXMLString(TEST_XML);
    const geomEl =
        mujoco.mjs_findElement(spec, mujoco.mjtObj.mjOBJ_GEOM, 'myplane');
    try {
      assertExists(geomEl);
      const geom = mujoco.mjs_asGeom(geomEl);
      assertExists(geom);
      const geomName = mujoco.mjs_getName(geom.element);
      expect(geomName).toEqual('myplane');
      mujoco.mjs_setName(geom.element, 'myplane2');
      expect(mujoco.mjs_getName(geom.element)).toEqual('myplane2');
    } finally {
      spec?.delete();
    }
  });

  it('should override geom userdata', () => {
    const spec = mujoco.parseXMLString(TEST_XML);
    const geomEl =
        mujoco.mjs_findElement(spec, mujoco.mjtObj.mjOBJ_GEOM, 'myplane');
    try {
      assertExists(geomEl);
      const geom = mujoco.mjs_asGeom(geomEl);
      assertExists(geom);
      geom.userdata.set(0, 10);
      expect(geom.userdata.get(0)).toEqual(10);
    } finally {
      spec.delete();
    }
  })

  it('should override model geom_rgba', () => {
    const newValues = new Float32Array([0.1, 0.2, 0.3, 0.4]);
    model!.geom_rgba.set(newValues);
    const expected = new Float32Array(
        [0.1, 0.2, 0.3, 0.4, 0.5, 0.5, 0.5, 1, 0.5, 0.5, 0.5, 1]);
    expectArraysClose(model!.geom_rgba, expected);
  })

  it('should add a scaled vector to another vector', () => {
    const res = mujoco.DoubleBuffer.FromArray([1, 2, 3]);
    const vec = [4, 5, 6];
    const scale = 2;
    const expected = new Float64Array([9, 12, 15]);
    try {
      mujoco.mju_addToScl(res, vec, scale);
      expectArraysClose(res.GetView(), expected, 4);
    } finally {
      res.delete();
    }
  });

  it('should throw an error when mju_addToScl is called with incompatible sizes',
     () => {
       const res = mujoco.DoubleBuffer.FromArray([1, 2, 3]);
       const vec = [4, 5];
       const scale = 2;
       try {
         expect(() => {
           mujoco.mju_addToScl(res, vec, scale);
         })
             .toThrowError(
                 'MuJoCo Error: [mju_addToScl] res and vec must have equal size, got 3 and 2');
       } finally {
         res.delete();
       }
     });

  it('should sort an array with insertion sort', () => {
    const arr = mujoco.DoubleBuffer.FromArray([5, 2, 8, 1, 9]);
    const expected = new Float64Array([1, 2, 5, 8, 9]);
    try {
      mujoco.mju_insertionSort(arr);
      expectArraysEqual(arr.GetView(), expected);
    } finally {
      arr.delete();
    }
  });

  it('should find the attached spec', () => {
    const bXml = `
    <mujoco>
      <worldbody>
        <body name="b" pos="0 0 0.1">
          <geom rgba="0 .9 0 1" name="attached_geom_b" type="box" size="0.1 0.1 0.1" mass="0.25"/>
          <freejoint name="bfree"/>
        </body>
      </worldbody>
    </mujoco>
    `;
    const xmlWithAttachedSpec = `
    <mujoco>
      <asset>
        <model name="b" file="b.xml" />
      </asset>

      <worldbody>
        <attach model="b" body="b" prefix="b" />
      </worldbody>
    </mujoco>
    `;
    const mainXmlFilename = 'main.xml';
    const bXmlFilename = 'b.xml';
    writeXMLFile(mainXmlFilename, xmlWithAttachedSpec);
    writeXMLFile(bXmlFilename, bXml);
    const spec = mujoco.parseXMLString(xmlWithAttachedSpec);
    const attachedSpec = mujoco.mjs_findSpec(spec, 'b');

    try {
      assertExists(attachedSpec);
      const geomEl = mujoco.mjs_findElement(
          attachedSpec, mujoco.mjtObj.mjOBJ_GEOM, 'attached_geom_b');
      assertExists(geomEl);
      const geom = mujoco.mjs_asGeom(geomEl);
      expect(geom).toBeDefined();
      expect(mujoco.mjs_getName(geom!.element)).toEqual('attached_geom_b');
    } finally {
      attachedSpec?.delete();
      spec?.delete();
      unlinkXMLFile(mainXmlFilename);
      unlinkXMLFile(bXmlFilename);
    }
  });

  // Corresponds to bindings_test.py:test_load_xml_can_handle_name_clash
  it('should handle name clashes when loading XML with includes', () => {
    const xml1 = `
      <mujoco>
        <worldbody>
          <geom name="plane" type="plane" size="1 1 1"/>
          <include file="model_.xml"/>
          <include file="model__.xml"/>
        </worldbody>
      </mujoco>
    `;
    const xml2 = `<mujoco><geom name="box" type="box" size="1 1 1"/></mujoco>`;
    const xml3 = `<mujoco><geom name="ball" type="sphere" size="1"/></mujoco>`;

    const modelXmlFilename = 'model.xml';
    const model1XmlFilename = 'model_.xml';
    const model2XmlFilename = 'model__.xml';

    writeXMLFile(modelXmlFilename, xml1);
    writeXMLFile(model1XmlFilename, xml2);
    writeXMLFile(model2XmlFilename, xml3);

    const model = mujoco.MjModel!.mj_loadXML(modelXmlFilename);

    try {
      expect(model).toBeDefined();
      expect(mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_GEOM.value, 'plane'))
          .toBe(0);
      expect(mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_GEOM.value, 'box'))
          .toBe(1);
      expect(mujoco.mj_name2id(model!, mujoco.mjtObj.mjOBJ_GEOM.value, 'ball'))
          .toBe(2);
    } finally {
      model?.delete();
      unlinkXMLFile(modelXmlFilename);
      unlinkXMLFile(model1XmlFilename);
      unlinkXMLFile(model2XmlFilename);
    }
  });

  // Corresponds to bindings_test.py:test_can_read_array
  it('should read an array from the model', () => {
    const expected =
        new Float64Array([0, 0, 0, 0, 0, 0.1, 0, 0, 1, 2, 0, 1, 42, 0, 42]);
    const bodyPos = new Float64Array(model!.body_pos);
    expectArraysEqual(bodyPos, expected);
  });

  // Corresponds to bindings_test.py:test_can_set_array
  it('should set an array from the data', () => {
    const value = 0.12345;
    data!.qpos.fill(value);
    const expected = new Float64Array(data!.qpos.length).fill(value);
    expectArraysEqual(data!.qpos, expected);
  });

  // Corresponds to bindings_test.py:test_array_is_a_view
  it('should check that array is a view', () => {
    const qposRef = data!.qpos;
    const value = 0.789;
    data!.qpos.fill(value);
    const expected = new Float64Array(data!.qpos.length).fill(value);
    expectArraysEqual(qposRef, expected);
  });

  // Corresponds to bindings_test.py:test_mjmodel_can_read_and_write_opt
  it('should read and write MjOption', () => {
    expect(model!.opt.timestep).toEqual(0.002);
    expectArraysEqual(model!.opt.gravity, new Float64Array([0, 0, -9.81]));

    const optRef = model!.opt;
    model!.opt.timestep = 0.001;
    expect(optRef.timestep).toEqual(0.001);

    const gravityRef = optRef.gravity;
    model!.opt.gravity[1] = 0.1;
    expectArraysEqual(gravityRef, new Float64Array([0, 0.1, -9.81]));

    model!.opt.gravity.fill(0.2);
    expectArraysEqual(gravityRef, new Float64Array([0.2, 0.2, 0.2]));
  });

  // Corresponds to bindings_test.py:test_mjmodel_can_read_and_write_stat
  it('should read and write MjStat', () => {
    expect(model!.stat.meanmass).not.toEqual(0);

    const statRef = model!.stat;
    model!.stat.meanmass = 1.2;
    expect(statRef.meanmass).toEqual(1.2);
  });

  // Corresponds to bindings_test.py:test_mjmodel_can_read_and_write_vis
  it('should read and write MjVis', () => {
    expect(model!.vis.quality.shadowsize).toEqual(51);

    const visRef = model!.vis;
    model!.vis.quality.shadowsize = 100;
    expect(visRef.quality.shadowsize).toEqual(100);
  });

  // Corresponds to bindings_test.py:test_mjmodel_can_access_names_directly
  it('should access names directly from the model', () => {
    const modelName = new TextDecoder().decode(
        model!.names.slice(0, model!.names.indexOf(0)));
    expect(modelName).toEqual('test');

    const startGeomNameIndex = model!.name_geomadr[0];
    const endGeomNameIndex = model!.names.indexOf(0, startGeomNameIndex);
    const geomName = new TextDecoder().decode(
        model!.names.slice(startGeomNameIndex, endGeomNameIndex));
    expect(geomName).toEqual('myplane');
  });

  // Corresponds to bindings_test.py:test_mjmodel_names_doesnt_copy
  it('should not copy names when accessing them multiple times', () => {
    const names1 = model!.names;
    const names2 = model!.names;
    expect(names1).toEqual(names2);
  });

  // Corresponds to bindings_test.py:test_mjoption_can_make_default
  it('should create a default MjOption', () => {
    const opt = new mujoco.MjOption();
    expect(opt.timestep).toEqual(0.002);
    expectArraysEqual(opt.gravity, new Float64Array([0, 0, -9.81]));
  });

  // Corresponds to bindings_test.py:test_mjoption_can_copy
  it('should copy MjOption', () => {
    const opt1 = new mujoco.MjOption();
    opt1.timestep = 0.001;
    opt1.gravity.set([2, 2, 2]);

    const opt2 = opt1.copy();
    expect(opt2.timestep).toEqual(0.001);
    expectArraysEqual(opt2.gravity, new Float64Array([2, 2, 2]));

    opt1.timestep = 0.005;
    opt1.gravity.set([5, 5, 5]);
    expect(opt2.timestep).toEqual(0.001);
    expectArraysEqual(opt2.gravity, new Float64Array([2, 2, 2]));