core: Fix TestContext2Apply_countTainted

The prior behavior being asserted by this test was incorrect, since the
configuration calls for there to be two instances of the resource at the
end.

We also now assert on the generated plan since it's important to verify
that we are indeed planning to replace the zeroth instance but not the
first instance (which doesn't yet exist).

terraform/context_apply_test.go

@@ -2380,19 +2380,43 @@ func TestContext2Apply_countTainted(t *testing.T) {
 		State: s,
 	})
 
-	if _, diags := ctx.Plan(); diags.HasErrors() {
-		t.Fatalf("plan errors: %s", diags.Err())
+	{
+		plan, diags := ctx.Plan()
+		assertNoErrors(t, diags)
+		got := strings.TrimSpace(legacyDiffComparisonString(plan.Changes))
+		want := strings.TrimSpace(`
+DESTROY/CREATE: aws_instance.foo[0]
+  foo:  "foo" => "foo"
+  id:   "bar" => "<computed>"
+  type: "aws_instance" => "aws_instance"
+CREATE: aws_instance.foo[1]
+  foo:  "" => "foo"
+  id:   "" => "<computed>"
+  type: "" => "aws_instance"
+`)
+		if got != want {
+			t.Fatalf("wrong plan\n\ngot:\n%s\n\nwant:\n%s", got, want)
+		}
 	}
 
 	state, diags := ctx.Apply()
-	if diags.HasErrors() {
-		t.Fatalf("diags: %s", diags.Err())
-	}
+	assertNoErrors(t, diags)
 
 	got := strings.TrimSpace(state.String())
-	want := strings.TrimSpace(testTerraformApplyCountTaintedStr)
+	want := strings.TrimSpace(`
+aws_instance.foo.0:
+  ID = foo
+  provider = provider.aws
+  foo = foo
+  type = aws_instance
+aws_instance.foo.1:
+  ID = foo
+  provider = provider.aws
+  foo = foo
+  type = aws_instance
+`)
 	if got != want {
-		t.Fatalf("wrong result\n\ngot:\n%s\n\nwant:\n%s", got, want)
+		t.Fatalf("wrong final state\n\ngot:\n%s\n\nwant:\n%s", got, want)
 	}
 }
 

terraform/terraform_test.go

@@ -492,10 +492,6 @@ aws_instance.foo.0:
   type = aws_instance
 `
 
-const testTerraformApplyCountTaintedStr = `
-<no state>
-`
-
 const testTerraformApplyCountVariableStr = `
 aws_instance.foo.0:
   ID = foo