diff --git a/charts_common/lib/src/chart/layout/layout_config.dart b/charts_common/lib/src/chart/layout/layout_config.dart
index 1ef635e39..2859bbf13 100644
--- a/charts_common/lib/src/chart/layout/layout_config.dart
+++ b/charts_common/lib/src/chart/layout/layout_config.dart
@@ -13,6 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import 'dart:math' show min;
+
 /// Collection of configurations that apply to the [LayoutManager].
 class LayoutConfig {
   final MarginSpec leftSpec;
@@ -97,25 +99,41 @@ class MarginSpec {
 
   /// Get the min pixels, given the [totalPixels].
   int getMinPixels(int totalPixels) {
+    int result;
+
+    if (totalPixels == null) {
+      totalPixels = 0;
+    }
+
+    // All paths must set result
     if (_minPixel != null) {
-      assert(_minPixel < totalPixels);
-      return _minPixel;
+      result = min(_minPixel, totalPixels);
     } else if (_minPercent != null) {
-      return (totalPixels * (_minPercent / 100)).round();
+      result = (totalPixels * (_minPercent / 100)).round();
     } else {
-      return 0;
+      result = 0;
     }
+
+    return result >= 0 ? result : 0;
   }
 
   /// Get the max pixels, given the [totalPixels].
   int getMaxPixels(int totalPixels) {
+    int result;
+
+    if (totalPixels == null) {
+      totalPixels = 0;
+    }
+
+    // All paths must set result
     if (_maxPixel != null) {
-      assert(_maxPixel < totalPixels);
-      return _maxPixel;
+      result = min(_maxPixel, totalPixels);
     } else if (_maxPercent != null) {
-      return (totalPixels * (_maxPercent / 100)).round();
+      result = (totalPixels * (_maxPercent / 100)).round();
     } else {
-      return totalPixels;
+      result = totalPixels;
     }
+
+    return result >= 0 ? result : 0;
   }
 }
diff --git a/charts_common/test/chart/layout/layout_manager_impl_test.dart b/charts_common/test/chart/layout/layout_manager_impl_test.dart
index 88f0a8a99..b9782fab2 100644
--- a/charts_common/test/chart/layout/layout_manager_impl_test.dart
+++ b/charts_common/test/chart/layout/layout_manager_impl_test.dart
@@ -45,4 +45,370 @@ void main() {
     expect(layout.marginBottom, equals(10));
     expect(layout.marginLeft, equals(9));
   });
+
+  test('marginSpec.fromPixel default', () {
+    var ms = MarginSpec.fromPixel();
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPixel(minPixel: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPixel(minPixel: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPixel(minPixel: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPixel: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPixel(maxPixel: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPixel(maxPixel: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPixel(maxPixel: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPixel: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPixel(minPixel: 0, maxPixel: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPixel(minPixel: 0, maxPixel: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPixel(minPixel: 0, maxPixel: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPixel: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPixel(minPixel: -1, maxPixel: 0)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPixel(minPixel: -1, maxPixel: 0), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPixel(minPixel: -1, maxPixel: 0);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPixel: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPixel(minPixel: -1, maxPixel: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPixel(minPixel: -1, maxPixel: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPixel(minPixel: -1, maxPixel: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPixel: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPixel(minPixel: 0)', () {
+    var ms = MarginSpec.fromPixel(minPixel: 0);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPixel(minPixel: 1)', () {
+    var ms = MarginSpec.fromPixel(minPixel: 1);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(1));
+    expect(ms.getMinPixels(1000000), equals(1));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPixel(minPixel: 100)', () {
+    var ms = MarginSpec.fromPixel(minPixel: 100);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(1));
+    expect(ms.getMinPixels(1000000), equals(100));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPixel(maxPixel: 100)', () {
+    var ms = MarginSpec.fromPixel(maxPixel: 100);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(100));
+  });
+
+  test('marginSpec.fromPixel(minPixel: 50, maxPixel: 100)', () {
+    var ms = MarginSpec.fromPixel(minPixel: 50, maxPixel: 100);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(1));
+    expect(ms.getMinPixels(1000000), equals(50));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(100));
+  });
+
+  test('marginSpec.fromPercent default', () {
+    var ms = MarginSpec.fromPercent();
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPercent(minPercent: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPercent(minPercent: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPercent(minPercent: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPercent: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPercent(maxPercent: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPercent(maxPercent: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPercent(maxPercent: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPercent: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPercent(minPercent: 0, maxPercent: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPercent(minPercent: 0, maxPercent: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPercent(minPercent: 0, maxPercent: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPercent: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPercent(minPercent: -1, maxPercent: 0)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPercent(minPercent: -1, maxPercent: 0), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPercent(minPercent: -1, maxPercent: 0);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPercent: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPercent(minPercent: -1, maxPercent: -1)', () {
+    // This didn't work :(
+    //expect(MarginSpec.fromPercent(minPercent: -1, maxPercent: -1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fromPercent(minPercent: -1, maxPercent: -1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      //print('minPercent: caught error');
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fromPercent(minPercent: 0)', () {
+    var ms = MarginSpec.fromPercent(minPercent: 0);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPercent(minPercent: 1)', () {
+    var ms = MarginSpec.fromPercent(minPercent: 1);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(10000));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPercent(minPercent: 100)', () {
+    var ms = MarginSpec.fromPercent(minPercent: 100);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(1));
+    expect(ms.getMinPixels(1000000), equals(1000000));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fromPercent(minPercent: 50, maxPercent: 100)', () {
+    var ms = MarginSpec.fromPercent(minPercent: 50, maxPercent: 100);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(1));
+    expect(ms.getMinPixels(1000000), equals(500000));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fixedPixel(null) ', () {
+    var ms = MarginSpec.fixedPixel(null);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(1000000));
+  });
+
+  test('marginSpec.fixedPixel(-1) ', () {
+    // This didn't work :(
+    //expect(MarginSpec.fixedPixel(-1), throwsA(isA<AssertionError>()));
+
+    try {
+        MarginSpec.fixedPixel(-1);
+        expect(false, equals(true), reason: 'Expected assert error, run with: `pub run test xxx` or `dart --enable-asserts xxx`');
+    } catch (e) {
+      expect(e.runtimeType.toString(), equals('_AssertionError'));
+    }
+  });
+
+  test('marginSpec.fixedPixel(0) ', () {
+    var ms = MarginSpec.fixedPixel(0);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(0));
+    expect(ms.getMinPixels(1000000), equals(0));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(0));
+    expect(ms.getMaxPixels(1000000), equals(0));
+  });
+
+  test('marginSpec.fixedPixel(100) ', () {
+    var ms = MarginSpec.fixedPixel(100);
+
+    expect(ms.getMinPixels(null), equals(0));
+    expect(ms.getMinPixels(-1), equals(0));
+    expect(ms.getMinPixels(0), equals(0));
+    expect(ms.getMinPixels(1), equals(1));
+    expect(ms.getMinPixels(1000000), equals(100));
+
+    expect(ms.getMaxPixels(null), equals(0));
+    expect(ms.getMaxPixels(-1), equals(0));
+    expect(ms.getMaxPixels(0), equals(0));
+    expect(ms.getMaxPixels(1), equals(1));
+    expect(ms.getMaxPixels(1000000), equals(100));
+  });
 }