diff --git a/android/rule_builder_test.go b/android/rule_builder_test.go
index cfbc2ab..6eba4f1 100644
--- a/android/rule_builder_test.go
+++ b/android/rule_builder_test.go
@@ -38,6 +38,7 @@
 			"ls":      nil,
 			"turbine": nil,
 			"java":    nil,
+			"javac":   nil,
 		})
 }
 
@@ -235,6 +236,34 @@
 	// ls --sort=time,size
 }
 
+func ExampleRuleBuilderCommand_FlagWithRspFileInputList() {
+	ctx := pathContext()
+	fmt.Println(NewRuleBuilder().Command().
+		Tool(PathForSource(ctx, "javac")).
+		FlagWithRspFileInputList("@", PathsForTesting("a.java", "b.java")).
+		NinjaEscapedString())
+	// Output:
+	// javac @$out.rsp
+}
+
+func ExampleRuleBuilderCommand_String() {
+	fmt.Println(NewRuleBuilder().Command().
+		Text("FOO=foo").
+		Text("echo $FOO").
+		String())
+	// Output:
+	// FOO=foo echo $FOO
+}
+
+func ExampleRuleBuilderCommand_NinjaEscapedString() {
+	fmt.Println(NewRuleBuilder().Command().
+		Text("FOO=foo").
+		Text("echo $FOO").
+		NinjaEscapedString())
+	// Output:
+	// FOO=foo echo $$FOO
+}
+
 func TestRuleBuilder(t *testing.T) {
 	fs := map[string][]byte{
 		"dep_fixer": nil,
@@ -503,3 +532,77 @@
 			"cp bar "+outFile, outFile, outFile+".d", true, nil)
 	})
 }
+
+func Test_ninjaEscapeExceptForSpans(t *testing.T) {
+	type args struct {
+		s     string
+		spans [][2]int
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "empty",
+			args: args{
+				s: "",
+			},
+			want: "",
+		},
+		{
+			name: "unescape none",
+			args: args{
+				s: "$abc",
+			},
+			want: "$$abc",
+		},
+		{
+			name: "unescape all",
+			args: args{
+				s:     "$abc",
+				spans: [][2]int{{0, 4}},
+			},
+			want: "$abc",
+		},
+		{
+			name: "unescape first",
+			args: args{
+				s:     "$abc$",
+				spans: [][2]int{{0, 1}},
+			},
+			want: "$abc$$",
+		},
+		{
+			name: "unescape last",
+			args: args{
+				s:     "$abc$",
+				spans: [][2]int{{4, 5}},
+			},
+			want: "$$abc$",
+		},
+		{
+			name: "unescape middle",
+			args: args{
+				s:     "$a$b$c$",
+				spans: [][2]int{{2, 5}},
+			},
+			want: "$$a$b$c$$",
+		},
+		{
+			name: "unescape multiple",
+			args: args{
+				s:     "$a$b$c$",
+				spans: [][2]int{{2, 3}, {4, 5}},
+			},
+			want: "$$a$b$c$$",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := ninjaEscapeExceptForSpans(tt.args.s, tt.args.spans); got != tt.want {
+				t.Errorf("ninjaEscapeExceptForSpans() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}