From 3e901336643b988ae45ae86c485005b8865e6e04 Mon Sep 17 00:00:00 2001
From: Dimitar Nanov <mitko.n@gmail.com>
Date: Sun, 8 Dec 2019 11:54:07 +0200
Subject: [PATCH] feat: display `multipleOf` constrains (#1065)

---
 demo/openapi.yaml                   |  1 +
 src/utils/__tests__/openapi.test.ts | 21 ++++++++++++++++++---
 src/utils/openapi.ts                | 16 ++++++++++++++++
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/demo/openapi.yaml b/demo/openapi.yaml
index d10fdf73..c34740ee 100644
--- a/demo/openapi.yaml
+++ b/demo/openapi.yaml
@@ -738,6 +738,7 @@ components:
               type: number
               description: Average amount of honey produced per day in ounces
               example: 3.14
+              multipleOf: .01
           required:
             - honeyPerDay
     Id:
diff --git a/src/utils/__tests__/openapi.test.ts b/src/utils/__tests__/openapi.test.ts
index 244ab63c..bcdfb193 100644
--- a/src/utils/__tests__/openapi.test.ts
+++ b/src/utils/__tests__/openapi.test.ts
@@ -333,7 +333,8 @@ describe('Utils', () => {
     const itemConstraintSchema = (
       min: number | undefined = undefined,
       max: number | undefined = undefined,
-    ) => ({ type: 'array', minItems: min, maxItems: max });
+      multipleOf: number | undefined = undefined,
+    ) => ({ type: 'array', minItems: min, maxItems: max, multipleOf });
 
     it('should not have a humanized constraint without schema constraints', () => {
       expect(humanizeConstraints(itemConstraintSchema())).toHaveLength(0);
@@ -355,9 +356,21 @@ describe('Utils', () => {
       expect(humanizeConstraints(itemConstraintSchema(7, 7))).toContain('7 items');
     });
 
-    it('should have a humazined constraint when justMinItems is set, and it is equal to 1', () => {
+    it('should have a humanized constraint when justMinItems is set, and it is equal to 1', () => {
       expect(humanizeConstraints(itemConstraintSchema(1))).toContain('non-empty');
     });
+
+    it('should have a humanized constraint when multipleOf is set, and it is in format of /^0\\.0*1$/', () => {
+      expect(humanizeConstraints(itemConstraintSchema(undefined, undefined, 0.01))).toContain(
+        'decimal places <= 2',
+      );
+    });
+
+    it('should have a humanized constraint when multipleOf is set, and it is in format other than /^0\\.0*1$/', () => {
+      expect(humanizeConstraints(itemConstraintSchema(undefined, undefined, 0.5))).toContain(
+        'multiple of 0.5',
+      );
+    });
   });
 
   describe('OpenAPI pluralizeType', () => {
@@ -387,7 +400,9 @@ describe('Utils', () => {
       expect(pluralizeType('objects (Pet)')).toEqual('objects (Pet)');
       expect(pluralizeType('strings <email>')).toEqual('strings <email>');
       expect(pluralizeType('objects or strings')).toEqual('objects or strings');
-      expect(pluralizeType('objects (Pet) or numbers <int64>')).toEqual('objects (Pet) or numbers <int64>');
+      expect(pluralizeType('objects (Pet) or numbers <int64>')).toEqual(
+        'objects (Pet) or numbers <int64>',
+      );
     });
   });
 
diff --git a/src/utils/openapi.ts b/src/utils/openapi.ts
index 2836cfed..e9657547 100644
--- a/src/utils/openapi.ts
+++ b/src/utils/openapi.ts
@@ -368,6 +368,17 @@ export function isNamedDefinition(pointer?: string): boolean {
   return /^#\/components\/schemas\/[^\/]+$/.test(pointer || '');
 }
 
+function humanizeMultipleOfConstraint(multipleOf: number | undefined): string | undefined {
+  if (multipleOf === undefined) {
+    return;
+  }
+  const strigifiedMultipleOf = multipleOf.toString(10);
+  if (!/^0\.0*1$/.test(strigifiedMultipleOf)) {
+    return `multiple of ${strigifiedMultipleOf}`;
+  }
+  return `decimal places <= ${strigifiedMultipleOf.split('.')[1].length}`;
+}
+
 function humanizeRangeConstraint(
   description: string,
   min: number | undefined,
@@ -406,6 +417,11 @@ export function humanizeConstraints(schema: OpenAPISchema): string[] {
     res.push(arrayRange);
   }
 
+  const multipleOfConstraint = humanizeMultipleOfConstraint(schema.multipleOf);
+  if (multipleOfConstraint !== undefined) {
+    res.push(multipleOfConstraint);
+  }
+
   let numberRange;
   if (schema.minimum !== undefined && schema.maximum !== undefined) {
     numberRange = schema.exclusiveMinimum ? '( ' : '[ ';