test[isObjectOf]: clarify target var name and assertion messages

Author: Milly

is/object_of_test.ts

@@ -31,12 +31,14 @@ Deno.test("isObjectOf<T>", async (t) => {
     assertEquals(
       isObjectOf(predObj)({ a: 0, b: "a", c: true, d: "ignored" }),
       true,
+      "Undefined properties are ignored",
     );
     assertEquals(
       isObjectOf(predObj)(
         Object.assign(() => void 0, { a: 0, b: "a", c: true }),
       ),
       true,
+      "Function are treated as an object",
     );
   });
 
@@ -99,45 +101,55 @@ Deno.test("isObjectOf<T>", async (t) => {
     }
   });
 
-  await t.step("if 'predObj' has prototype properties", async (t) => {
-    const prototypeObj = {
-      a: is.Number,
-      b: is.Boolean,
-    };
-    // deno-lint-ignore ban-types
-    const predObj2 = Object.assign(Object.create(prototypeObj) as {}, {
-      c: is.String,
-    });
+  await t.step(
+    "does not affect prototype properties of 'predObj'",
+    async (t) => {
+      const prototypeObj = {
+        a: is.Number,
+        b: is.Boolean,
+      };
+      // deno-lint-ignore ban-types
+      const predObj = Object.assign(Object.create(prototypeObj) as {}, {
+        c: is.String,
+      });
 
-    await t.step("returns true on T object that omits prototype", () => {
-      assertEquals(isObjectOf(predObj2)({ c: "a" }), true);
-      assertEquals(
-        isObjectOf(predObj2)({ c: "a", d: "ignored" }),
-        true,
-      );
-      assertEquals(
-        isObjectOf(predObj2)(Object.assign(() => void 0, { c: "a" })),
-        true,
-      );
-    });
+      await t.step("returns true on T object", () => {
+        assertEquals(isObjectOf(predObj)({ c: "a" }), true);
+        assertEquals(
+          isObjectOf(predObj)({ a: "ignored", b: "ignored", c: "a" }),
+          true,
+          "Predicates defined in the prototype are ignored",
+        );
+        assertEquals(
+          isObjectOf(predObj)({ c: "a", d: "ignored" }),
+          true,
+          "Undefined properties are ignored",
+        );
+        assertEquals(
+          isObjectOf(predObj)(Object.assign(() => void 0, { c: "a" })),
+          true,
+          "Function are treated as an object",
+        );
+      });
 
-    await t.step("returns false on non T object that omits prototype", () => {
-      assertEquals(isObjectOf(predObj2)("a"), false, "Value is not an object");
-      assertEquals(
-        isObjectOf(predObj2)({ a: 0, b: true, c: 1 }),
-        false,
-        "Object have a different type property",
-      );
-      assertEquals(
-        isObjectOf(predObj2)({ a: 0, b: true }),
-        false,
-        "Object does not have one property",
-      );
-      assertEquals(
-        isObjectOf({ 0: is.String })(["a"]),
-        false,
-        "Value is not an object",
-      );
-    });
-  });
+      await t.step("returns false on non T object", () => {
+        assertEquals(isObjectOf(predObj)("a"), false, "Value is not an object");
+        assertEquals(
+          isObjectOf(predObj)({ a: 0, b: true, c: 1 }),
+          false,
+          "Object have a different type property",
+        );
+        assertEquals(
+          isObjectOf(predObj)({ a: 0, b: true }),
+          false,
+          "Object does not have one property",
+        );
+        assertEquals(
+          isObjectOf({ 0: is.String })(["a"]),
+          false,
+          "Value is not an object",
+        );
+      });
+    },
+  );
 });