diff --git a/packages/concerto-analysis/src/compare-config.ts b/packages/concerto-analysis/src/compare-config.ts
index 4ee56dbb8..cb36687e6 100644
--- a/packages/concerto-analysis/src/compare-config.ts
+++ b/packages/concerto-analysis/src/compare-config.ts
@@ -61,6 +61,10 @@ export const defaultCompareConfig: CompareConfig = {
         'property-validator-removed': CompareResult.PATCH,
         'property-validator-changed': CompareResult.MAJOR,
         'map-key-type-changed': CompareResult.MAJOR,
-        'map-value-type-changed': CompareResult.MAJOR
+        'map-value-type-changed': CompareResult.MAJOR,
+        'scalar-extends-changed': CompareResult.MAJOR,
+        'scalar-validator-added' : CompareResult.MAJOR,
+        'scalar-validator-removed' : CompareResult.PATCH,
+        'scalar-validator-changed' : CompareResult.MAJOR,
     }
 };
diff --git a/packages/concerto-analysis/src/compare-utils.ts b/packages/concerto-analysis/src/compare-utils.ts
index f0d8b926e..180d51aa0 100644
--- a/packages/concerto-analysis/src/compare-utils.ts
+++ b/packages/concerto-analysis/src/compare-utils.ts
@@ -12,7 +12,7 @@
  * limitations under the License.
  */
 
-import { ClassDeclaration, EnumValueDeclaration, Field, MapDeclaration, NumberValidator, Property, RelationshipDeclaration, StringValidator, Validator } from '@accordproject/concerto-core';
+import { ClassDeclaration, EnumValueDeclaration, Field, MapDeclaration, ScalarDeclaration, NumberValidator, Property, RelationshipDeclaration, StringValidator, Validator } from '@accordproject/concerto-core';
 import Declaration from '@accordproject/concerto-core/types/lib/introspect/declaration';
 
 export function getDeclarationType(declaration: Declaration) {
@@ -34,6 +34,11 @@ export function getDeclarationType(declaration: Declaration) {
         }
     } else if (declaration instanceof MapDeclaration) {
         return 'map';
+    } else if (declaration instanceof ScalarDeclaration) {
+        return 'scalar';
+    }
+    else {
+        throw new Error(`unknown declaration type "${declaration}"`);
     }
 }
 
diff --git a/packages/concerto-analysis/src/compare.ts b/packages/concerto-analysis/src/compare.ts
index 9d1fe21a4..76ff8228b 100644
--- a/packages/concerto-analysis/src/compare.ts
+++ b/packages/concerto-analysis/src/compare.ts
@@ -12,7 +12,7 @@
  * limitations under the License.
  */
 
-import { ClassDeclaration, MapDeclaration, ModelFile, Property } from '@accordproject/concerto-core';
+import { ClassDeclaration, MapDeclaration, ModelFile, Property, ScalarDeclaration } from '@accordproject/concerto-core';
 import { CompareConfig, CompareResult, defaultCompareConfig } from './compare-config';
 import { CompareFinding } from './compare-message';
 import { CompareResults } from './compare-results';
@@ -69,14 +69,26 @@ export class Compare {
         return b.filter(bItem => !a.some(aItem => bItem.getName() === aItem.getName()));
     }
 
+    private getAddedScalarDeclarations(a: ScalarDeclaration[], b: ScalarDeclaration[]): ScalarDeclaration[] {
+        return b.filter(bItem => !a.some(aItem => bItem.getName() === aItem.getName()));
+    }
+
     private getMatchingMapDeclarations(a: MapDeclaration[], b: MapDeclaration[]): [a: MapDeclaration, b: MapDeclaration][] {
         return a.map(aItem => [aItem, b.find(bItem => aItem.getName() === bItem.getName())]).filter(([, b]) => !!b) as [MapDeclaration, MapDeclaration][];
     }
 
+    private getMatchingScalarDeclarations(a: ScalarDeclaration[], b: ScalarDeclaration[]): [a: ScalarDeclaration, b: ScalarDeclaration][] {
+        return a.map(aItem => [aItem, b.find(bItem => aItem.getName() === bItem.getName())]).filter(([, b]) => !!b) as [ScalarDeclaration, ScalarDeclaration][];
+    }
+
     private getRemovedMapDeclarations(a: MapDeclaration[], b: MapDeclaration[]): MapDeclaration[] {
         return a.filter(aItem => !b.some(bItem => aItem.getName() === bItem.getName()));
     }
 
+    private getRemovedScalarDeclarations(a: ScalarDeclaration[], b: ScalarDeclaration[]): ScalarDeclaration[] {
+        return a.filter(aItem => !b.some(bItem => aItem.getName() === bItem.getName()));
+    }
+
     private getAddedClassDeclarations(a: ClassDeclaration[], b: ClassDeclaration[]): ClassDeclaration[] {
         return b.filter(bItem => !a.some(aItem => bItem.getName() === aItem.getName()));
     }
@@ -98,12 +110,26 @@ export class Compare {
         removed.forEach(a => comparers.forEach(comparer => comparer.compareMapDeclaration?.(a, undefined)));
     }
 
+    private compareScalarDeclarations(comparers: Comparer[], a: ScalarDeclaration[], b: ScalarDeclaration[]) {
+        const added = this.getAddedScalarDeclarations(a, b);
+        const matching = this.getMatchingScalarDeclarations(a, b);
+        const removed = this.getRemovedScalarDeclarations(a, b);
+        added.forEach(b => comparers.forEach(comparer => comparer.compareScalarDeclaration?.(undefined, b)));
+        matching.forEach(([a, b]) => comparers.forEach(comparer => comparer.compareScalarDeclaration?.(a, b)));
+        removed.forEach(a => comparers.forEach(comparer => comparer.compareScalarDeclaration?.(a, undefined)));
+    }
+
+
     private compareClassDeclaration(comparers: Comparer[], a: ClassDeclaration, b: ClassDeclaration) {
         comparers.forEach(comparer => comparer.compareClassDeclaration?.(a, b));
         // MapDeclarations do not contain properties, nothing to compare.
         if(a instanceof MapDeclaration || b instanceof MapDeclaration) {
             return;
         }
+        // ScalarDeclarations do not contain properties, nothing to compare.
+        if(a instanceof ScalarDeclaration || b instanceof ScalarDeclaration) {
+            return;
+        }
         this.compareProperties(comparers, a.getOwnProperties(), b.getOwnProperties());
     }
 
@@ -120,6 +146,7 @@ export class Compare {
         comparers.forEach(comparer => comparer.compareModelFiles?.(a, b));
         this.compareClassDeclarations(comparers, a.getAllDeclarations(), b.getAllDeclarations());
         this.compareMapDeclarations(comparers, a.getMapDeclarations(), b.getMapDeclarations());
+        this.compareScalarDeclarations(comparers, a.getScalarDeclarations(), b.getScalarDeclarations());
     }
 
     private buildResults(findings: CompareFinding[]) {
diff --git a/packages/concerto-analysis/src/comparer.ts b/packages/concerto-analysis/src/comparer.ts
index 65c55d6e4..125f02848 100644
--- a/packages/concerto-analysis/src/comparer.ts
+++ b/packages/concerto-analysis/src/comparer.ts
@@ -12,7 +12,7 @@
  * limitations under the License.
  */
 
-import { ClassDeclaration, MapDeclaration, ModelFile, Property } from '@accordproject/concerto-core';
+import { ClassDeclaration, MapDeclaration, ModelFile, Property, ScalarDeclaration } from '@accordproject/concerto-core';
 import { CompareContext } from './compare-context';
 
 /**
@@ -42,6 +42,15 @@ export type Comparer = {
      */
     compareMapDeclaration?: (a: MapDeclaration | undefined, b: MapDeclaration | undefined) => void;
 
+    /**
+     * Called to compare two scalar declarations. If a is undefined, but b is defined, then this scalar declaration was
+     * created in the second model. If a is defined, but b is undefined, then this map declaration was removed in the
+     * second model.
+     * @param a The first scalar declaration for comparision, or undefined if it is undefined in the first model.
+     * @param b The second scalar declaration for comparision, or undefined if it is undefined in the second model.
+     */
+    compareScalarDeclaration?: (a: ScalarDeclaration | undefined, b: ScalarDeclaration | undefined) => void;
+
     /**
      * Called to compare two properties. If a is undefined, but b is definecd, then this property was
      * created in the second model. If a is defined, but b is undefined, then this property was removed in the
diff --git a/packages/concerto-analysis/src/comparers/index.ts b/packages/concerto-analysis/src/comparers/index.ts
index 53fee5de5..cb0a8b004 100644
--- a/packages/concerto-analysis/src/comparers/index.ts
+++ b/packages/concerto-analysis/src/comparers/index.ts
@@ -16,10 +16,12 @@ import { classDeclarationComparerFactories } from './class-declarations';
 import { modelFileComparerFactories } from './model-files';
 import { propertyComparerFactories } from './properties';
 import { mapDeclarationComparerFactories } from './map-declarations';
+import { scalarDeclarationComparerFactories } from './scalar-declarations';
 
 export const comparerFactories = [
     ...classDeclarationComparerFactories,
     ...propertyComparerFactories,
     ...modelFileComparerFactories,
-    ...mapDeclarationComparerFactories
+    ...mapDeclarationComparerFactories,
+    ...scalarDeclarationComparerFactories
 ];
diff --git a/packages/concerto-analysis/src/comparers/scalar-declarations.ts b/packages/concerto-analysis/src/comparers/scalar-declarations.ts
new file mode 100644
index 000000000..a66eaa0b9
--- /dev/null
+++ b/packages/concerto-analysis/src/comparers/scalar-declarations.ts
@@ -0,0 +1,72 @@
+/*
+ * 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 { ComparerFactory } from '../comparer';
+import { getValidatorType } from '../compare-utils';
+
+const scalarDeclarationExtendsChanged: ComparerFactory = (context) => ({
+    compareScalarDeclaration: (a, b) => {
+
+        if (!a || !b) {
+            return;
+        }
+
+        if(a.getType() !== b.getType()) {
+            context.report({
+                key: 'scalar-extends-changed',
+                message: `The scalar extends was changed from "${a.getType()}" to "${b.getType()}"`,
+                element: b.getName()
+            });
+        }
+    },
+});
+
+const scalarValidatorChanged: ComparerFactory = (context) => ({
+    compareScalarDeclaration: (a, b) => {
+        if (!a || !b) {
+            return;
+        }
+        const aValidator = a.getValidator();
+        const bValidator = b.getValidator();
+        if (!aValidator && !bValidator) {
+            return;
+        } else if (!aValidator && bValidator) {
+            const bValidatorType = getValidatorType(bValidator);
+            context.report({
+                key: 'scalar-validator-added',
+                message: `A ${bValidatorType} validator was added to the scalar "${a.getName()}"`,
+                element: a.getName()
+            });
+            return;
+        } else if (aValidator && !bValidator) {
+            const aValidatorType = getValidatorType(aValidator);
+            context.report({
+                key: 'scalar-validator-removed',
+                message: `A ${aValidatorType} validator was removed from the scalar "${a.getName()}"`,
+                element: a.getName()
+            });
+            return;
+        } else if (!aValidator.compatibleWith(bValidator)) {
+            const aValidatorType = getValidatorType(aValidator);
+            context.report({
+                key: 'scalar-validator-changed',
+                message: `A ${aValidatorType} validator for the scalar "${a.getName()}" was changed and is no longer compatible`,
+                element: a.getName()
+            });
+            return;
+        }
+    }
+});
+
+export const scalarDeclarationComparerFactories = [scalarDeclarationExtendsChanged, scalarValidatorChanged];
diff --git a/packages/concerto-analysis/test/fixtures/scalar-added.cto b/packages/concerto-analysis/test/fixtures/scalar-added.cto
new file mode 100644
index 000000000..e5c18d692
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-added.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-changed-extends.cto b/packages/concerto-analysis/test/fixtures/scalar-changed-extends.cto
new file mode 100644
index 000000000..b97f3c24a
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-changed-extends.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends Integer
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-number-validator-added.cto b/packages/concerto-analysis/test/fixtures/scalar-number-validator-added.cto
new file mode 100644
index 000000000..6fdfb8590
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-number-validator-added.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends Integer range=[-1,1]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-lowercompat.cto b/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-lowercompat.cto
new file mode 100644
index 000000000..9852f8bd8
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-lowercompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends Integer range=[-2,1]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-uppercompat.cto b/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-uppercompat.cto
new file mode 100644
index 000000000..ff0cb8ef3
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-uppercompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends Integer range=[-1,2]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-upperincompat.cto b/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-upperincompat.cto
new file mode 100644
index 000000000..97563e93f
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-number-validator-changed-upperincompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends Integer range=[-1,0]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-number-validators.cto b/packages/concerto-analysis/test/fixtures/scalar-number-validators.cto
new file mode 100644
index 000000000..b97f3c24a
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-number-validators.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends Integer
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-added.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-added.cto
new file mode 100644
index 000000000..6fca5d28b
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-added.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String regex=/foo/
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-changed.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-changed.cto
new file mode 100644
index 000000000..8e145609f
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-changed.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String regex=/bar/
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-added.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-added.cto
new file mode 100644
index 000000000..8f58fb18f
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-added.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String length=[2,10]
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-lowercompat.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-lowercompat.cto
new file mode 100644
index 000000000..9f9e467dc
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-lowercompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String length=[1,10]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-lowerincompat.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-lowerincompat.cto
new file mode 100644
index 000000000..516170813
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-lowerincompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String length=[3,10]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-uppercompat.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-uppercompat.cto
new file mode 100644
index 000000000..6361234f8
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-uppercompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String length=[2,100]
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-upperincompat.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-upperincompat.cto
new file mode 100644
index 000000000..245d7982a
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validator-length-changed-upperincompat.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String length=[2,8]
diff --git a/packages/concerto-analysis/test/fixtures/scalar-string-validators.cto b/packages/concerto-analysis/test/fixtures/scalar-string-validators.cto
new file mode 100644
index 000000000..e5c18d692
--- /dev/null
+++ b/packages/concerto-analysis/test/fixtures/scalar-string-validators.cto
@@ -0,0 +1,3 @@
+namespace org.accordproject.concerto.test@1.2.3
+
+scalar Thing extends String
\ No newline at end of file
diff --git a/packages/concerto-analysis/test/unit/compare-utils.test.ts b/packages/concerto-analysis/test/unit/compare-utils.test.ts
index 58dae5241..3eb27680d 100644
--- a/packages/concerto-analysis/test/unit/compare-utils.test.ts
+++ b/packages/concerto-analysis/test/unit/compare-utils.test.ts
@@ -22,6 +22,11 @@ test('should throw for unknown class declaration type', () => {
     expect(() => getDeclarationType(classDeclaration)).toThrow('unknown class declaration type "ClassDeclaration {id=foo@1.0.0.undefined super=Concept enum=false abstract=false}"');
 });
 
+test('should throw for unknown thing', () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    expect(() => getDeclarationType('thing' as any)).toThrow('unknown declaration type "thing"');
+});
+
 test('should throw for unknown class property type', () => {
     expect(() => getPropertyType(property)).toThrow('unknown property type "[object Object]');
 });
diff --git a/packages/concerto-analysis/test/unit/compare.test.ts b/packages/concerto-analysis/test/unit/compare.test.ts
index fb8a38204..f192623e7 100644
--- a/packages/concerto-analysis/test/unit/compare.test.ts
+++ b/packages/concerto-analysis/test/unit/compare.test.ts
@@ -69,7 +69,7 @@ test('should detect a change of namespace', async () => {
     expect(results.result).toBe(CompareResult.ERROR);
 });
 
-['asset', 'concept', 'enum', 'event', 'participant', 'transaction', 'map'].forEach(type => {
+['asset', 'concept', 'enum', 'event', 'participant', 'transaction', 'map', 'scalar'].forEach(type => {
     test(`should detect a ${type} being added`, async () => {
         process.env.ENABLE_MAP_TYPE = 'true'; // TODO Remove on release of MapType
         const [a, b] = await getModelFiles('empty.cto', `${type}-added.cto`);
@@ -207,7 +207,7 @@ test('should detect a relationship changing to a field', async () => {
     expect(results.result).toBe(CompareResult.MAJOR);
 });
 
-test('should detect a scalar changing to an array', async () => {
+test('should detect a property changing to an array', async () => {
     const [a, b] = await getModelFiles('scalar-to-array-a.cto', 'scalar-to-array-b.cto');
     const results = new Compare().compare(a, b);
     expect(results.findings).toEqual(expect.arrayContaining([
@@ -219,7 +219,7 @@ test('should detect a scalar changing to an array', async () => {
     expect(results.result).toBe(CompareResult.MAJOR);
 });
 
-test('should detect an array changing to a scalar', async () => {
+test('should detect an array changing to a property', async () => {
     const [a, b] = await getModelFiles('scalar-to-array-b.cto', 'scalar-to-array-a.cto');
     const results = new Compare().compare(a, b);
     expect(results.findings).toEqual(expect.arrayContaining([
@@ -259,6 +259,19 @@ test('should detect a map value type changing from x to y', async () => {
     expect(results.result).toBe(CompareResult.MAJOR);
 });
 
+test('should detect a scalar extends changing from x to y', async () => {
+    const [a, b] = await getModelFiles('scalar-added.cto', 'scalar-changed-extends.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-extends-changed',
+            message: 'The scalar extends was changed from "String" to "Integer"'
+        })
+    ]));
+    expect(results.findings[0].message).toBe('The scalar extends was changed from "String" to "Integer"');
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
 test('should detect a primitive typed field changing to a declaration typed field', async () => {
     const [a, b] = await getModelFiles('primitive-to-declaration-a.cto', 'primitive-to-declaration-b.cto');
     const results = new Compare().compare(a, b);
@@ -481,6 +494,166 @@ test('should detect a string validator being changed on a property (incompatible
     expect(results.result).toBe(CompareResult.MAJOR);
 });
 
+test('should detect a number validator being added to a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-number-validators.cto', 'scalar-number-validator-added.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-added',
+            message: 'A number validator was added to the scalar "Thing"'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should detect a number validator being removed from a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-number-validator-added.cto', 'scalar-number-validators.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-removed',
+            message: 'A number validator was removed from the scalar "Thing"'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.PATCH);
+});
+
+test('should not detect a number validator being changed on a scalar (compatible lower bound)', async () => {
+    const [a, b] = await getModelFiles('scalar-number-validator-added.cto', 'scalar-number-validator-changed-lowercompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual([]);
+    expect(results.result).toBe(CompareResult.NONE);
+});
+
+test('should detect a number validator being changed on a property (incompatible lower bound)', async () => {
+    const [a, b] = await getModelFiles('number-validator-added.cto', 'number-validator-changed-lowerincompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'property-validator-changed',
+            message: 'A number validator for the field "number" in the concept "Thing" was changed and is no longer compatible'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should not detect a number validator being changed on a scalar (compatible upper bound)', async () => {
+    const [a, b] = await getModelFiles('scalar-number-validator-added.cto', 'scalar-number-validator-changed-uppercompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual([]);
+    expect(results.result).toBe(CompareResult.NONE);
+});
+
+test('should detect a number validator being changed on a property (incompatible upper bound)', async () => {
+    const [a, b] = await getModelFiles('scalar-number-validator-added.cto', 'scalar-number-validator-changed-upperincompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-changed',
+            message: 'A number validator for the scalar "Thing" was changed and is no longer compatible'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should detect a string validator being added to a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validators.cto', 'scalar-string-validator-added.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-added',
+            message: 'A string validator was added to the scalar "Thing"'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should detect a string validator being removed from a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validator-added.cto', 'scalar-string-validators.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-removed',
+            message: 'A string validator was removed from the scalar "Thing"'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.PATCH);
+});
+
+test('should detect a string validator being changed on a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validator-added.cto', 'scalar-string-validator-changed.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-changed',
+            message: 'A string validator for the scalar "Thing" was changed and is no longer compatible'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should detect a string length validator being added to a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validators.cto', 'scalar-string-validator-length-added.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-added',
+            message: 'A string validator was added to the scalar "Thing"'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should detect a string length validator being removed from a scalar', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validator-length-added.cto', 'scalar-string-validators.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-removed',
+            message: 'A string validator was removed from the scalar "Thing"'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.PATCH);
+});
+
+test('should not detect a string length validator being changed on a property (compatible minLength bound)', async () => {
+    const [a, b] = await getModelFiles('string-validator-length-added.cto', 'string-validator-length-changed-lowercompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual([]);
+    expect(results.result).toBe(CompareResult.NONE);
+});
+
+test('should detect a string length validator being changed on a scalar (incompatible minLength bound)', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validator-length-added.cto', 'scalar-string-validator-length-changed-lowerincompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-changed',
+            message: 'A string validator for the scalar "Thing" was changed and is no longer compatible'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
+test('should not detect a string validator being changed on a scalar (compatible maxLength bound)', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validator-length-added.cto', 'scalar-string-validator-length-changed-uppercompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual([]);
+    expect(results.result).toBe(CompareResult.NONE);
+});
+
+test('should detect a string validator being changed on a scalar (incompatible maxLength bound)', async () => {
+    const [a, b] = await getModelFiles('scalar-string-validator-length-added.cto', 'scalar-string-validator-length-changed-upperincompat.cto');
+    const results = new Compare().compare(a, b);
+    expect(results.findings).toEqual(expect.arrayContaining([
+        expect.objectContaining({
+            key: 'scalar-validator-changed',
+            message: 'A string validator for the scalar "Thing" was changed and is no longer compatible'
+        })
+    ]));
+    expect(results.result).toBe(CompareResult.MAJOR);
+});
+
 test('should give a MAJOR CompareResult for Map Type compare config rules)', async () => {
     expect(defaultCompareConfig.rules['map-key-type-changed']).toBe(CompareResult.MAJOR);
     expect(defaultCompareConfig.rules['map-value-type-changed']).toBe(CompareResult.MAJOR);