internal/imports: test exported functions with nil args

Test the api of the internal imports package to make sure that it does
not crash when given nil as opts or Env.

Change-Id: I0127d550a49f63040efb16c07e8cff8b599bbe3c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/190000
Reviewed-by: Heschi Kreinick <heschi@google.com>

internal/imports/imports_test.go

@@ -0,0 +1,74 @@
+package imports
+
+import (
+	"go/build"
+	"testing"
+)
+
+// TestNilOpts tests that process does not crash with nil opts.
+func TestNilOpts(t *testing.T) {
+	var testOpts = []struct {
+		name string
+		opt  *Options
+	}{
+		{
+			name: "nil",
+			opt:  nil,
+		},
+		{
+			name: "nil env",
+			opt:  &Options{Comments: true, TabIndent: true, TabWidth: 8},
+		},
+		{
+			name: "default",
+			opt: &Options{
+				Env: &ProcessEnv{
+					GOPATH: build.Default.GOPATH,
+					GOROOT: build.Default.GOROOT,
+				},
+				Comments:  true,
+				TabIndent: true,
+				TabWidth:  8,
+			},
+		},
+	}
+
+	input := `package p
+
+func _() {
+	fmt.Println()
+}
+`
+	want := `package p
+
+import "fmt"
+
+func _() {
+	fmt.Println()
+}
+`
+	for _, test := range testOpts {
+		// Test Process
+		got, err := Process("", []byte(input), test.opt)
+		if err != nil {
+			t.Errorf("%s: %s", test.name, err.Error())
+		}
+		if string(got) != want {
+			t.Errorf("%s: Process: Got:\n%s\nWant:\n%s\n", test.name, string(got), want)
+		}
+
+		// Test FixImports and ApplyFixes
+		fixes, err := FixImports("", []byte(input), test.opt)
+		if err != nil {
+			t.Errorf("%s: %s", test.name, err.Error())
+		}
+
+		got, err = ApplyFixes(fixes, "", []byte(input), test.opt)
+		if err != nil {
+			t.Errorf("%s: %s", test.name, err.Error())
+		}
+		if string(got) != want {
+			t.Errorf("%s: ApplyFix: Got:\n%s\nWant:\n%s\n", test.name, string(got), want)
+		}
+	}
+}