noyalib 0.0.5

A pure Rust YAML library with zero unsafe code and full serde integration
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220

// SPDX-License-Identifier: MIT OR Apache-2.0
// Copyright (c) 2026 Noyalib. All rights reserved.

//! `Value::interpolate_properties` — `${name}` substitution inside
//! string scalars, with strict and lossy variants.

#![allow(missing_docs)]

use noyalib::{Mapping, Tag, TaggedValue, Value, from_str};
use std::collections::HashMap;

fn props(pairs: &[(&str, &str)]) -> HashMap<String, String> {
    pairs
        .iter()
        .map(|(k, v)| (k.to_string(), v.to_string()))
        .collect()
}

#[test]
fn interpolates_top_level_string() {
    let mut v: Value = from_str("name: ${APP}").unwrap();
    v.interpolate_properties(&props(&[("APP", "noyalib")]))
        .unwrap();
    assert_eq!(v["name"].as_str(), Some("noyalib"));
}

#[test]
fn interpolates_nested_mapping() {
    let mut v: Value =
        from_str("service:\n  name: ${APP}\n  url: https://${HOST}:${PORT}/api\n").unwrap();
    let map = props(&[
        ("APP", "noyalib"),
        ("HOST", "api.example.com"),
        ("PORT", "8443"),
    ]);
    v.interpolate_properties(&map).unwrap();
    assert_eq!(v["service"]["name"].as_str(), Some("noyalib"));
    assert_eq!(
        v["service"]["url"].as_str(),
        Some("https://api.example.com:8443/api"),
    );
}

#[test]
fn interpolates_inside_sequence() {
    let mut v: Value = from_str("items:\n  - hello ${WHO}\n  - bye ${WHO}\n").unwrap();
    v.interpolate_properties(&props(&[("WHO", "world")]))
        .unwrap();
    assert_eq!(v["items"][0].as_str(), Some("hello world"));
    assert_eq!(v["items"][1].as_str(), Some("bye world"));
}

#[test]
fn does_not_touch_keys() {
    // The mapping key `${APP}` is left as-is — only values are
    // interpolated. This avoids surprising key-rename interactions.
    let mut v: Value = from_str("\"${APP}\": me\nname: ${APP}\n").unwrap();
    v.interpolate_properties(&props(&[("APP", "noyalib")]))
        .unwrap();
    let map = match &v {
        Value::Mapping(m) => m,
        _ => panic!("expected mapping"),
    };
    assert!(
        map.contains_key("${APP}"),
        "literal placeholder key must survive"
    );
    assert!(!map.contains_key("noyalib"), "value-only interpolation");
    assert_eq!(v["name"].as_str(), Some("noyalib"));
}

#[test]
fn does_not_touch_non_string_scalars() {
    let mut v: Value = from_str("port: 8080\nflag: true\nnull_val: null\n").unwrap();
    v.interpolate_properties(&props(&[("X", "y")])).unwrap();
    // None of these had string content; tree unchanged.
    assert_eq!(v["port"].as_i64(), Some(8080));
    assert_eq!(v["flag"].as_bool(), Some(true));
    assert!(v["null_val"].is_null());
}

#[test]
fn unknown_placeholder_errors_in_strict_mode() {
    let mut v: Value = from_str("name: ${MISSING}").unwrap();
    let err = v
        .interpolate_properties::<String>(&HashMap::new())
        .unwrap_err();
    let msg = err.to_string();
    assert!(
        msg.contains("MISSING"),
        "error must name the placeholder: {msg}"
    );
}

#[test]
fn unknown_placeholder_substitutes_empty_in_lossy_mode() {
    let mut v: Value = from_str("greeting: hello ${WHO} and ${OTHER}").unwrap();
    v.interpolate_properties_lossy(&props(&[("WHO", "world")]));
    assert_eq!(v["greeting"].as_str(), Some("hello world and "));
}

#[test]
fn escape_double_brace_is_literal_dollar_brace() {
    let mut v: Value = from_str("template: \"price: ${{USD}\"").unwrap();
    v.interpolate_properties(&props(&[("USD", "ignored")]))
        .unwrap();
    assert_eq!(v["template"].as_str(), Some("price: ${USD}"));
}

#[test]
fn escape_double_close_brace_is_literal() {
    let mut v: Value = from_str("template: \"a}}b\"").unwrap();
    v.interpolate_properties(&props(&[])).unwrap();
    assert_eq!(v["template"].as_str(), Some("a}b"));
}

#[test]
fn dotted_placeholder_names_supported() {
    let mut v: Value = from_str("url: ${db.host}:${db.port}").unwrap();
    v.interpolate_properties(&props(&[("db.host", "db1"), ("db.port", "5432")]))
        .unwrap();
    assert_eq!(v["url"].as_str(), Some("db1:5432"));
}

#[test]
fn unterminated_placeholder_errors() {
    let mut v: Value = from_str("name: \"${UNCLOSED\"").unwrap();
    let err = v
        .interpolate_properties::<String>(&HashMap::new())
        .unwrap_err();
    assert!(err.to_string().contains("unterminated"));
}

#[test]
fn empty_placeholder_errors() {
    let mut v: Value = from_str("name: \"${}\"").unwrap();
    let err = v
        .interpolate_properties::<String>(&HashMap::new())
        .unwrap_err();
    assert!(err.to_string().contains("empty placeholder"));
}

#[test]
fn invalid_placeholder_character_errors() {
    let mut v: Value = from_str("name: \"${A B}\"").unwrap();
    let err = v
        .interpolate_properties::<String>(&HashMap::new())
        .unwrap_err();
    assert!(err.to_string().contains("invalid character"));
}

#[test]
fn no_dollar_means_no_walk_no_change() {
    // Strings without `${` or `}` should not allocate.
    let mut v: Value = from_str("a: hello\nb: world\nc: 42\n").unwrap();
    let before = v.clone();
    v.interpolate_properties(&props(&[("APP", "noyalib")]))
        .unwrap();
    assert_eq!(v, before);
}

#[test]
fn unicode_around_placeholder_preserved() {
    let mut v: Value = from_str("greeting: \"héllo ${WHO} 🌍\"").unwrap();
    v.interpolate_properties(&props(&[("WHO", "wörld")]))
        .unwrap();
    assert_eq!(v["greeting"].as_str(), Some("héllo wörld 🌍"));
}

#[test]
fn descends_into_tagged_value() {
    // Build a `Value::Tagged` directly — the typed Value loader
    // resolves most user tags into their target shape, so we
    // construct the wrapper programmatically to exercise the
    // interpolate-walks-into-Tagged path.
    let inner = Value::String("v=${V}".into());
    let tagged = Value::Tagged(Box::new(TaggedValue::new(Tag::new("!Version"), inner)));

    let mut map = Mapping::new();
    let _ = map.insert("tagged", tagged);
    let mut v = Value::Mapping(map);

    v.interpolate_properties(&props(&[("V", "1.2.3")])).unwrap();

    let inner_after = match &v["tagged"] {
        Value::Tagged(boxed) => boxed.value(),
        other => panic!("expected tagged, got {other:?}"),
    };
    assert_eq!(inner_after.as_str(), Some("v=1.2.3"));
}

#[test]
fn nested_lossy_substitution_in_complex_doc() {
    let mut v: Value = from_str(
        "config:
  servers:
    - name: ${A}
      url: https://${HOST_A}/
    - name: ${B}
      url: https://${HOST_B}/
",
    )
    .unwrap();

    let map = props(&[
        ("A", "alpha"),
        ("HOST_A", "alpha.example.com"),
        ("B", "beta"),
    ]);
    v.interpolate_properties_lossy(&map);

    let s0 = &v["config"]["servers"][0];
    assert_eq!(s0["name"].as_str(), Some("alpha"));
    assert_eq!(s0["url"].as_str(), Some("https://alpha.example.com/"));

    let s1 = &v["config"]["servers"][1];
    assert_eq!(s1["name"].as_str(), Some("beta"));
    // HOST_B missing → empty in lossy mode.
    assert_eq!(s1["url"].as_str(), Some("https:///"));
}