correctly narrow "number" type to "integer", fixes #1935

lib/compile/validate/index.ts

@@ -286,7 +286,7 @@ function checkContextTypes(it: SchemaObjCxt, types: JSONType[]): void {
       strictTypesError(it, `type "${t}" not allowed by context "${it.dataTypes.join(",")}"`)
     }
   })
-  it.dataTypes = it.dataTypes.filter((t) => includesType(types, t))
+  narrowSchemaTypes(it, types)
 }
 
 function checkMultipleTypes(it: SchemaObjCxt, ts: JSONType[]): void {
@@ -316,6 +316,15 @@ function includesType(ts: JSONType[], t: JSONType): boolean {
   return ts.includes(t) || (t === "integer" && ts.includes("number"))
 }
 
+function narrowSchemaTypes(it: SchemaObjCxt, withTypes: JSONType[]): void {
+  const ts: JSONType[] = []
+  for (const t of it.dataTypes) {
+    if (includesType(withTypes, t)) ts.push(t)
+    else if (withTypes.includes("integer") && t === "number") ts.push("integer")
+  }
+  it.dataTypes = ts
+}
+
 function strictTypesError(it: SchemaObjCxt, msg: string): void {
   const schemaPath = it.schemaEnv.baseId + it.errSchemaPath
   msg += ` at "${schemaPath}" (strictTypes)`

spec/issues/1935_integer_narrowing_subschema.spec.ts

@@ -0,0 +1,111 @@
+import _Ajv from "../ajv"
+import Ajv from "ajv"
+import * as assert from "assert"
+
+describe("integer valid type in number sub-schema (issue #1935)", () => {
+  let ajv: Ajv
+  before(() => {
+    ajv = new _Ajv({strict: true})
+  })
+
+  it("should allow integer in `if`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        if: {
+          type: "integer",
+          maximum: 5,
+        },
+        else: {
+          minimum: 10,
+        },
+      })
+    ))
+
+  it("should allow integer in `then`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        if: {
+          multipleOf: 2,
+        },
+        then: {
+          type: "integer",
+          minimum: 10,
+        },
+      })
+    ))
+
+  it("should allow integer in `else`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        if: {
+          maximum: 5,
+        },
+        else: {
+          type: "integer",
+          minimum: 10,
+        },
+      })
+    ))
+
+  it("should allow integer in `allOf`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        allOf: [
+          {
+            type: "integer",
+            minimum: 10,
+          },
+          {
+            multipleOf: 2,
+          },
+        ],
+      })
+    ))
+
+  it("should allow integer in `oneOf`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        oneOf: [
+          {
+            type: "integer",
+            minimum: 10,
+          },
+          {
+            multipleOf: 2,
+          },
+        ],
+      })
+    ))
+
+  it("should allow integer in `anyOf`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        oneOf: [
+          {
+            type: "integer",
+            minimum: 10,
+          },
+          {
+            multipleOf: 2,
+          },
+        ],
+      })
+    ))
+
+  it("should allow integer in `not`", () =>
+    assert.doesNotThrow(() =>
+      ajv.compile({
+        type: "number",
+        not: {
+          type: "integer",
+          minimum: 10,
+        },
+      })
+    ))
+})