curves_test.dart 19.6 KB
Newer Older
Ian Hickson's avatar
Ian Hickson committed
1
// Copyright 2014 The Flutter Authors. All rights reserved.
2 3 4
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

5 6
// @dart = 2.8

7 8
import 'dart:math' as math;

9 10 11 12 13 14 15
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/animation.dart';
import 'package:flutter/widgets.dart';

void main() {
  test('toString control test', () {
    expect(Curves.linear, hasOneLineDescription);
16 17
    expect(const SawTooth(3), hasOneLineDescription);
    expect(const Interval(0.25, 0.75), hasOneLineDescription);
18
    expect(const Interval(0.25, 0.75, curve: Curves.ease), hasOneLineDescription);
19 20 21
  });

  test('Curve flipped control test', () {
22
    const Curve ease = Curves.ease;
23
    final Curve flippedEase = ease.flipped;
24 25 26 27 28 29
    expect(flippedEase.transform(0.0), lessThan(0.001));
    expect(flippedEase.transform(0.5), lessThan(ease.transform(0.5)));
    expect(flippedEase.transform(1.0), greaterThan(0.999));
    expect(flippedEase, hasOneLineDescription);
  });

30
  test('Threshold has a threshold', () {
31
    const Curve step = Threshold(0.25);
32 33 34 35 36 37
    expect(step.transform(0.0), 0.0);
    expect(step.transform(0.24), 0.0);
    expect(step.transform(0.25), 1.0);
    expect(step.transform(0.26), 1.0);
    expect(step.transform(1.0), 1.0);
  });
38

39 40 41 42 43 44 45 46 47 48 49
  void assertMaximumSlope(Curve curve, double maximumSlope) {
    const double delta = 0.005;
    for (double x = 0.0; x < 1.0 - delta; x += delta) {
      final double deltaY = curve.transform(x) - curve.transform(x + delta);
      assert(deltaY.abs() < delta * maximumSlope, '${curve.toString()} discontinuous at $x');
    }
  }

  test('Curve is continuous', () {
    assertMaximumSlope(Curves.linear, 20.0);
    assertMaximumSlope(Curves.decelerate, 20.0);
50
    assertMaximumSlope(Curves.fastOutSlowIn, 20.0);
51
    assertMaximumSlope(Curves.slowMiddle, 20.0);
52 53 54 55 56 57
    assertMaximumSlope(Curves.bounceIn, 20.0);
    assertMaximumSlope(Curves.bounceOut, 20.0);
    assertMaximumSlope(Curves.bounceInOut, 20.0);
    assertMaximumSlope(Curves.elasticOut, 20.0);
    assertMaximumSlope(Curves.elasticInOut, 20.0);
    assertMaximumSlope(Curves.ease, 20.0);
58

59
    assertMaximumSlope(Curves.easeIn, 20.0);
60 61 62 63 64 65 66 67
    assertMaximumSlope(Curves.easeInSine, 20.0);
    assertMaximumSlope(Curves.easeInQuad, 20.0);
    assertMaximumSlope(Curves.easeInCubic, 20.0);
    assertMaximumSlope(Curves.easeInQuart, 20.0);
    assertMaximumSlope(Curves.easeInQuint, 20.0);
    assertMaximumSlope(Curves.easeInExpo, 20.0);
    assertMaximumSlope(Curves.easeInCirc, 20.0);

68
    assertMaximumSlope(Curves.easeOut, 20.0);
69 70 71 72 73 74 75 76 77 78 79
    assertMaximumSlope(Curves.easeOutSine, 20.0);
    assertMaximumSlope(Curves.easeOutQuad, 20.0);
    assertMaximumSlope(Curves.easeOutCubic, 20.0);
    assertMaximumSlope(Curves.easeOutQuart, 20.0);
    assertMaximumSlope(Curves.easeOutQuint, 20.0);
    assertMaximumSlope(Curves.easeOutExpo, 20.0);
    assertMaximumSlope(Curves.easeOutCirc, 20.0);

    // Curves.easeInOutExpo is discontinuous at its midpoint, so not included
    // here

80
    assertMaximumSlope(Curves.easeInOut, 20.0);
81 82 83 84 85 86
    assertMaximumSlope(Curves.easeInOutSine, 20.0);
    assertMaximumSlope(Curves.easeInOutQuad, 20.0);
    assertMaximumSlope(Curves.easeInOutCubic, 20.0);
    assertMaximumSlope(Curves.easeInOutQuart, 20.0);
    assertMaximumSlope(Curves.easeInOutQuint, 20.0);
    assertMaximumSlope(Curves.easeInOutCirc, 20.0);
87 88
  });

89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109
  void expectStaysInBounds(Curve curve) {
    expect(curve.transform(0.0), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.1), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.2), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.3), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.4), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.5), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.6), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.7), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.8), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(0.9), inInclusiveRange(0.0, 1.0));
    expect(curve.transform(1.0), inInclusiveRange(0.0, 1.0));
  }

  test('Bounce stays in bounds', () {
    expectStaysInBounds(Curves.bounceIn);
    expectStaysInBounds(Curves.bounceOut);
    expectStaysInBounds(Curves.bounceInOut);
  });

  List<double> estimateBounds(Curve curve) {
110 111 112 113 114 115 116 117 118 119 120 121 122
    final List<double> values = <double>[
      curve.transform(0.0),
      curve.transform(0.1),
      curve.transform(0.2),
      curve.transform(0.3),
      curve.transform(0.4),
      curve.transform(0.5),
      curve.transform(0.6),
      curve.transform(0.7),
      curve.transform(0.8),
      curve.transform(0.9),
      curve.transform(1.0),
    ];
123 124 125 126 127 128 129

    return <double>[
      values.reduce(math.min),
      values.reduce(math.max),
    ];
  }

130
  test('Elastic overshoots its bounds', () {
131 132 133 134 135 136 137 138 139 140 141 142 143 144 145
    expect(Curves.elasticIn, hasOneLineDescription);
    expect(Curves.elasticOut, hasOneLineDescription);
    expect(Curves.elasticInOut, hasOneLineDescription);

    List<double> bounds;
    bounds = estimateBounds(Curves.elasticIn);
    expect(bounds[0], lessThan(0.0));
    expect(bounds[1], lessThanOrEqualTo(1.0));
    bounds = estimateBounds(Curves.elasticOut);
    expect(bounds[0], greaterThanOrEqualTo(0.0));
    expect(bounds[1], greaterThan(1.0));
    bounds = estimateBounds(Curves.elasticInOut);
    expect(bounds[0], lessThan(0.0));
    expect(bounds[1], greaterThan(1.0));
  });
146

147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163
  test('Back overshoots its bounds', () {
    expect(Curves.easeInBack, hasOneLineDescription);
    expect(Curves.easeOutBack, hasOneLineDescription);
    expect(Curves.easeInOutBack, hasOneLineDescription);

    List<double> bounds;
    bounds = estimateBounds(Curves.easeInBack);
    expect(bounds[0], lessThan(0.0));
    expect(bounds[1], lessThanOrEqualTo(1.0));
    bounds = estimateBounds(Curves.easeOutBack);
    expect(bounds[0], greaterThanOrEqualTo(0.0));
    expect(bounds[1], greaterThan(1.0));
    bounds = estimateBounds(Curves.easeInOutBack);
    expect(bounds[0], lessThan(0.0));
    expect(bounds[1], greaterThan(1.0));
  });

164 165 166
  test('Decelerate does so', () {
    expect(Curves.decelerate, hasOneLineDescription);

167
    final List<double> bounds = estimateBounds(Curves.decelerate);
168 169 170
    expect(bounds[0], greaterThanOrEqualTo(0.0));
    expect(bounds[1], lessThanOrEqualTo(1.0));

171 172
    final double d1 = Curves.decelerate.transform(0.2) - Curves.decelerate.transform(0.0);
    final double d2 = Curves.decelerate.transform(1.0) - Curves.decelerate.transform(0.8);
173 174
    expect(d2, lessThan(d1));
  });
175 176

  test('Invalid transform parameter should assert', () {
177 178
    expect(() => const SawTooth(2).transform(-0.0001), throwsAssertionError);
    expect(() => const SawTooth(2).transform(1.0001), throwsAssertionError);
179

180 181
    expect(() => const Interval(0.0, 1.0).transform(-0.0001), throwsAssertionError);
    expect(() => const Interval(0.0, 1.0).transform(1.0001), throwsAssertionError);
182

183 184
    expect(() => const Threshold(0.5).transform(-0.0001), throwsAssertionError);
    expect(() => const Threshold(0.5).transform(1.0001), throwsAssertionError);
185

186 187
    expect(() => const ElasticInCurve().transform(-0.0001), throwsAssertionError);
    expect(() => const ElasticInCurve().transform(1.0001), throwsAssertionError);
188

189 190
    expect(() => const ElasticOutCurve().transform(-0.0001), throwsAssertionError);
    expect(() => const ElasticOutCurve().transform(1.0001), throwsAssertionError);
191

192 193
    expect(() => const Cubic(0.42, 0.0, 0.58, 1.0).transform(-0.0001), throwsAssertionError);
    expect(() => const Cubic(0.42, 0.0, 0.58, 1.0).transform(1.0001), throwsAssertionError);
194

195 196
    expect(() => Curves.decelerate.transform(-0.0001), throwsAssertionError);
    expect(() => Curves.decelerate.transform(1.0001), throwsAssertionError);
197

198 199
    expect(() => Curves.bounceIn.transform(-0.0001), throwsAssertionError);
    expect(() => Curves.bounceIn.transform(1.0001), throwsAssertionError);
200

201 202
    expect(() => Curves.bounceOut.transform(-0.0001), throwsAssertionError);
    expect(() => Curves.bounceOut.transform(1.0001), throwsAssertionError);
203

204 205
    expect(() => Curves.bounceInOut.transform(-0.0001), throwsAssertionError);
    expect(() => Curves.bounceInOut.transform(1.0001), throwsAssertionError);
206 207
  });

208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248
  test('Curve transform method should return 0.0 for t=0.0 and 1.0 for t=1.0', () {
    expect(const SawTooth(2).transform(0), 0);
    expect(const SawTooth(2).transform(1), 1);

    expect(const Interval(0, 1).transform(0), 0);
    expect(const Interval(0, 1).transform(1), 1);

    expect(const Threshold(0.5).transform(0), 0);
    expect(const Threshold(0.5).transform(1), 1);

    expect(const ElasticInCurve().transform(0), 0);
    expect(const ElasticInCurve().transform(1), 1);

    expect(const ElasticOutCurve().transform(0), 0);
    expect(const ElasticOutCurve().transform(1), 1);

    expect(const ElasticInOutCurve().transform(0), 0);
    expect(const ElasticInOutCurve().transform(1), 1);

    expect(Curves.linear.transform(0), 0);
    expect(Curves.linear.transform(1), 1);

    expect(Curves.easeInOutExpo.transform(0), 0);
    expect(Curves.easeInOutExpo.transform(1), 1);

    expect(const FlippedCurve(Curves.easeInOutExpo).transform(0), 0);
    expect(const FlippedCurve(Curves.easeInOutExpo).transform(1), 1);

    expect(Curves.decelerate.transform(0), 0);
    expect(Curves.decelerate.transform(1), 1);

    expect(Curves.bounceIn.transform(0), 0);
    expect(Curves.bounceIn.transform(1), 1);

    expect(Curves.bounceOut.transform(0), 0);
    expect(Curves.bounceOut.transform(1), 1);

    expect(Curves.bounceInOut.transform(0), 0);
    expect(Curves.bounceInOut.transform(1), 1);
  });

249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580
  test('CatmullRomSpline interpolates values properly', () {
    final CatmullRomSpline curve = CatmullRomSpline(
      const <Offset>[
        Offset(0.0, 0.0),
        Offset(0.01, 0.25),
        Offset(0.2, 0.25),
        Offset(0.33, 0.25),
        Offset(0.5, 1.0),
        Offset(0.66, 0.75),
        Offset(1.0, 1.0),
      ],
      tension: 0.0,
      startHandle: const Offset(0.0, -0.3),
      endHandle: const Offset(1.3, 1.3),
    );
    expect(curve.transform(0.0).dx, closeTo(0.0, 1e-6));
    expect(curve.transform(0.0).dy, closeTo(0.0, 1e-6));
    expect(curve.transform(0.25).dx, closeTo(0.0966945, 1e-6));
    expect(curve.transform(0.25).dy, closeTo(0.2626806, 1e-6));
    expect(curve.transform(0.5).dx, closeTo(0.33, 1e-6));
    expect(curve.transform(0.5).dy, closeTo(0.25, 1e-6));
    expect(curve.transform(0.75).dx, closeTo(0.570260, 1e-6));
    expect(curve.transform(0.75).dy, closeTo(0.883085, 1e-6));
    expect(curve.transform(1.0).dx, closeTo(1.0, 1e-6));
    expect(curve.transform(1.0).dy, closeTo(1.0, 1e-6));
  });
  test('CatmullRomSpline enforces contract', () {
    expect(() {
      CatmullRomSpline(null);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline(const <Offset>[]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline(const <Offset>[Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline(const <Offset>[Offset.zero, Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline(const <Offset>[Offset.zero, Offset.zero, Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline(const <Offset>[Offset.zero, Offset.zero, Offset.zero, Offset.zero], tension: -1.0);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline(const <Offset>[Offset.zero, Offset.zero, Offset.zero, Offset.zero], tension: 2.0);
    }, throwsAssertionError);
  });
  test('CatmullRomSpline interpolates values properly when precomputed', () {
    final CatmullRomSpline curve = CatmullRomSpline.precompute(
      const <Offset>[
        Offset(0.0, 0.0),
        Offset(0.01, 0.25),
        Offset(0.2, 0.25),
        Offset(0.33, 0.25),
        Offset(0.5, 1.0),
        Offset(0.66, 0.75),
        Offset(1.0, 1.0),
      ],
      tension: 0.0,
      startHandle: const Offset(0.0, -0.3),
      endHandle: const Offset(1.3, 1.3),
    );
    expect(curve.transform(0.0).dx, closeTo(0.0, 1e-6));
    expect(curve.transform(0.0).dy, closeTo(0.0, 1e-6));
    expect(curve.transform(0.25).dx, closeTo(0.0966945, 1e-6));
    expect(curve.transform(0.25).dy, closeTo(0.2626806, 1e-6));
    expect(curve.transform(0.5).dx, closeTo(0.33, 1e-6));
    expect(curve.transform(0.5).dy, closeTo(0.25, 1e-6));
    expect(curve.transform(0.75).dx, closeTo(0.570260, 1e-6));
    expect(curve.transform(0.75).dy, closeTo(0.883085, 1e-6));
    expect(curve.transform(1.0).dx, closeTo(1.0, 1e-6));
    expect(curve.transform(1.0).dy, closeTo(1.0, 1e-6));
  });
  test('CatmullRomSpline enforces contract when precomputed', () {
    expect(() {
      CatmullRomSpline.precompute(null);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline.precompute(const <Offset>[]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline.precompute(const <Offset>[Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline.precompute(const <Offset>[Offset.zero, Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline.precompute(const <Offset>[Offset.zero, Offset.zero, Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline.precompute(const <Offset>[Offset.zero, Offset.zero, Offset.zero, Offset.zero], tension: -1.0);
    }, throwsAssertionError);
    expect(() {
      CatmullRomSpline.precompute(const <Offset>[Offset.zero, Offset.zero, Offset.zero, Offset.zero], tension: 2.0);
    }, throwsAssertionError);
  });
  test('CatmullRomCurve interpolates given points correctly', () {
    final CatmullRomCurve curve = CatmullRomCurve(
      const <Offset>[
        Offset(0.2, 0.25),
        Offset(0.33, 0.25),
        Offset(0.5, 1.0),
        Offset(0.8, 0.75),
      ],
    );

    // These values are approximations.
    const double tolerance = 1e-6;
    expect(curve.transform(0.0), closeTo(0.0, tolerance));
    expect(curve.transform(0.01), closeTo(0.012874734350170863, tolerance));
    expect(curve.transform(0.2), closeTo(0.24989646045277542, tolerance));
    expect(curve.transform(0.33), closeTo(0.250037698527661, tolerance));
    expect(curve.transform(0.5), closeTo(0.9999057323235939, tolerance));
    expect(curve.transform(0.6), closeTo(0.9357294964536621, tolerance));
    expect(curve.transform(0.8), closeTo(0.7500423402378034, tolerance));
    expect(curve.transform(1.0), closeTo(1.0, tolerance));
  });
  test('CatmullRomCurve interpolates given points correctly when precomputed', () {
    final CatmullRomCurve curve = CatmullRomCurve.precompute(
      const <Offset>[
        Offset(0.2, 0.25),
        Offset(0.33, 0.25),
        Offset(0.5, 1.0),
        Offset(0.8, 0.75),
      ],
    );

    // These values are approximations.
    const double tolerance = 1e-6;
    expect(curve.transform(0.0), closeTo(0.0, tolerance));
    expect(curve.transform(0.01), closeTo(0.012874734350170863, tolerance));
    expect(curve.transform(0.2), closeTo(0.24989646045277542, tolerance));
    expect(curve.transform(0.33), closeTo(0.250037698527661, tolerance));
    expect(curve.transform(0.5), closeTo(0.9999057323235939, tolerance));
    expect(curve.transform(0.6), closeTo(0.9357294964536621, tolerance));
    expect(curve.transform(0.8), closeTo(0.7500423402378034, tolerance));
    expect(curve.transform(1.0), closeTo(1.0, tolerance));
  });
  test('CatmullRomCurve enforces contract', () {
    expect(() {
      CatmullRomCurve(null);
    }, throwsAssertionError);
    expect(() {
      CatmullRomCurve(const <Offset>[]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomCurve(const <Offset>[Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomCurve(const <Offset>[Offset.zero, Offset.zero]);
    }, throwsAssertionError);

    // Monotonically increasing in X.
    expect(
        CatmullRomCurve.validateControlPoints(
          const <Offset>[
            Offset(0.2, 0.25),
            Offset(0.01, 0.25),
          ],
          tension: 0.0,
        ),
        isFalse);
    expect(() {
      CatmullRomCurve(
        const <Offset>[
          Offset(0.2, 0.25),
          Offset(0.01, 0.25),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // X within range (0.0, 1.0).
    expect(
        CatmullRomCurve.validateControlPoints(
          const <Offset>[
            Offset(0.2, 0.25),
            Offset(1.01, 0.25),
          ],
          tension: 0.0,
        ),
        isFalse);
    expect(() {
      CatmullRomCurve(
        const <Offset>[
          Offset(0.2, 0.25),
          Offset(1.01, 0.25),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // Not multi-valued in Y at x=0.0.
    expect(
      CatmullRomCurve.validateControlPoints(
        const <Offset>[
          Offset(0.05, 0.50),
          Offset(0.50, 0.50),
          Offset(0.75, 0.75),
        ],
        tension: 0.0,
      ),
      isFalse,
    );
    expect(() {
      CatmullRomCurve(
        const <Offset>[
          Offset(0.05, 0.50),
          Offset(0.50, 0.50),
          Offset(0.75, 0.75),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // Not multi-valued in Y at x=1.0.
    expect(
      CatmullRomCurve.validateControlPoints(
        const <Offset>[
          Offset(0.25, 0.25),
          Offset(0.50, 0.50),
          Offset(0.95, 0.51),
        ],
        tension: 0.0,
      ),
      isFalse,
    );
    expect(() {
      CatmullRomCurve(
        const <Offset>[
          Offset(0.25, 0.25),
          Offset(0.50, 0.50),
          Offset(0.95, 0.51),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // Not multi-valued in Y in between x = 0.0 and x = 1.0.
    expect(
      CatmullRomCurve.validateControlPoints(
        const <Offset>[
          Offset(0.5, 0.05),
          Offset(0.5, 0.95),
        ],
        tension: 0.0,
      ),
      isFalse,
    );
    expect(() {
      CatmullRomCurve(
        const <Offset>[
          Offset(0.5, 0.05),
          Offset(0.5, 0.95),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);
  });
  test('CatmullRomCurve enforces contract when precomputed', () {
    expect(() {
      CatmullRomCurve.precompute(null);
    }, throwsAssertionError);
    expect(() {
      CatmullRomCurve.precompute(const <Offset>[]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomCurve.precompute(const <Offset>[Offset.zero]);
    }, throwsAssertionError);
    expect(() {
      CatmullRomCurve.precompute(const <Offset>[Offset.zero, Offset.zero]);
    }, throwsAssertionError);

    // Monotonically increasing in X.
    expect(() {
      CatmullRomCurve.precompute(
        const <Offset>[
          Offset(0.2, 0.25),
          Offset(0.01, 0.25),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // X within range (0.0, 1.0).
    expect(() {
      CatmullRomCurve.precompute(
        const <Offset>[
          Offset(0.2, 0.25),
          Offset(1.01, 0.25),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // Not multi-valued in Y at x=0.0.
    expect(() {
      CatmullRomCurve.precompute(
        const <Offset>[
          Offset(0.05, 0.50),
          Offset(0.50, 0.50),
          Offset(0.75, 0.75),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // Not multi-valued in Y at x=1.0.
    expect(() {
      CatmullRomCurve.precompute(
        const <Offset>[
          Offset(0.25, 0.25),
          Offset(0.50, 0.50),
          Offset(0.95, 0.51),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);

    // Not multi-valued in Y in between x = 0.0 and x = 1.0.
    expect(() {
      CatmullRomCurve.precompute(
        const <Offset>[
          Offset(0.5, 0.05),
          Offset(0.5, 0.95),
        ],
        tension: 0.0,
      );
    }, throwsAssertionError);
  });
581
}