expect: Fix edge case in part 19 (#8394)

* expect: Fix edge case in part 19 * Remove distracting gap in Received for negative assertion * Add opposite test case for negative assertion
jestjs · Apr 30, 2019 · ff9985c · ff9985c
1 parent d387bcf
commit ff9985c
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Showing 3 changed files with 42 additions and 15 deletions.
diff --git a/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap b/packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
@@ -1369,6 +1369,22 @@ Received constructor:     <red>E</> extends … extends <green>B</>
 "
 `;
 
+exports[`.toBeInstanceOf() passing {} and [Function B] 3`] = `
+"<dim>expect(</><red>received</><dim>).</>not<dim>.</>toBeInstanceOf<dim>(</><green>expected</><dim>)</>
+
+Expected constructor: not <green>B</>
+Received constructor name is not a string
+"
+`;
+
+exports[`.toBeInstanceOf() passing {} and [Function anonymous] 1`] = `
+"<dim>expect(</><red>received</><dim>).</>not<dim>.</>toBeInstanceOf<dim>(</><green>expected</><dim>)</>
+
+Expected constructor name is an empty string
+Received constructor: <red>SubHasNameProp</>
+"
+`;
+
 exports[`.toBeInstanceOf() passing {} and [Function name() {}] 1`] = `
 "<dim>expect(</><red>received</><dim>).</>not<dim>.</>toBeInstanceOf<dim>(</><green>expected</><dim>)</>
 

diff --git a/packages/expect/src/__tests__/matchers.test.js b/packages/expect/src/__tests__/matchers.test.js
@@ -690,6 +690,13 @@ describe('.toBeInstanceOf()', () => {
   class D extends C {}
   class E extends D {}
 
+  class SubHasStaticNameMethod extends B {
+    constructor() {
+      super();
+    }
+    static name() {}
+  }
+
   class HasStaticNameMethod {
     constructor() {}
     static name() {}
@@ -702,14 +709,17 @@ describe('.toBeInstanceOf()', () => {
     value: '',
     writable: true,
   });
+  class SubHasNameProp extends DefinesNameProp {}
 
   [
     [new Map(), Map],
     [[], Array],
     [new A(), A],
     [new C(), B], // C extends B
     [new E(), B], // E extends … extends B
-    [new HasStaticNameMethod(), HasStaticNameMethod],
+    [new SubHasNameProp(), DefinesNameProp], // omit extends
+    [new SubHasStaticNameMethod(), B], // Received
+    [new HasStaticNameMethod(), HasStaticNameMethod], // Expected
   ].forEach(([a, b]) => {
     test(`passing ${stringify(a)} and ${stringify(b)}`, () => {
       expect(() =>

diff --git a/packages/expect/src/print.ts b/packages/expect/src/print.ts
@@ -149,23 +149,24 @@ export const printReceivedConstructorName = (
   received: Function,
 ) => printConstructorName(label, received, false, false) + '\n';
 
-export function printReceivedConstructorNameNot(
+// Do not call function if received is equal to expected.
+export const printReceivedConstructorNameNot = (
   label: string,
   received: Function,
   expected: Function,
-) {
-  let printed = printConstructorName(label, received, true, false);
-
-  if (typeof received.name === 'string' && received.name.length !== 0) {
-    printed += ` ${
-      Object.getPrototypeOf(received) === expected
-        ? 'extends'
-        : 'extends … extends'
-    } ${EXPECTED_COLOR(expected.name)}`;
-  }
-
-  return printed + '\n';
-}
+) =>
+  typeof expected.name === 'string' &&
+  expected.name.length !== 0 &&
+  typeof received.name === 'string' &&
+  received.name.length !== 0
+    ? printConstructorName(label, received, true, false) +
+      ` ${
+        Object.getPrototypeOf(received) === expected
+          ? 'extends'
+          : 'extends … extends'
+      } ${EXPECTED_COLOR(expected.name)}` +
+      '\n'
+    : printConstructorName(label, received, false, false) + '\n';
 
 const printConstructorName = (
   label: string,