Add no_std support via disabling the new default feature std (#319)

schemars/tests/expected/no_std.json

@@ -0,0 +1,70 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "title": "MyStruct",
+  "type": "object",
+  "properties": {
+    "my_int": {
+      "type": "integer",
+      "format": "int32"
+    },
+    "my_bool": {
+      "type": "boolean"
+    },
+    "my_nullable_enum": {
+      "anyOf": [
+        {
+          "$ref": "#/$defs/MyEnum"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    }
+  },
+  "required": [
+    "my_int",
+    "my_bool"
+  ],
+  "$defs": {
+    "MyEnum": {
+      "oneOf": [
+        {
+          "type": "object",
+          "properties": {
+            "StringNewType": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "StringNewType"
+          ],
+          "additionalProperties": false
+        },
+        {
+          "type": "object",
+          "properties": {
+            "StructVariant": {
+              "type": "object",
+              "properties": {
+                "floats": {
+                  "type": "array",
+                  "items": {
+                    "type": "number",
+                    "format": "float"
+                  }
+                }
+              },
+              "required": [
+                "floats"
+              ]
+            }
+          },
+          "required": [
+            "StructVariant"
+          ],
+          "additionalProperties": false
+        }
+      ]
+    }
+  }
+}

schemars/tests/no_std.rs

@@ -0,0 +1,25 @@
+#![no_std]
+
+mod util;
+use schemars::JsonSchema;
+use util::*;
+
+extern crate alloc as test_alloc;
+
+#[derive(JsonSchema)]
+pub struct MyStruct {
+    pub my_int: i32,
+    pub my_bool: bool,
+    pub my_nullable_enum: Option<MyEnum>,
+}
+
+#[derive(JsonSchema)]
+pub enum MyEnum {
+    StringNewType(test_alloc::string::String),
+    StructVariant { floats: test_alloc::vec::Vec<f32> },
+}
+
+#[test]
+fn no_std() -> TestResult {
+    test_default_generated_schema::<MyStruct>("no_std")
+}

schemars/tests/remote_derive_generic.rs

@@ -2,7 +2,7 @@ mod util;
 
 use schemars::JsonSchema;
 use serde::Serialize;
-use std::collections::{HashMap, HashSet};
+use std::collections::{BTreeMap, BTreeSet};
 use util::*;
 
 #[allow(dead_code)]
@@ -39,7 +39,7 @@ struct MyStruct<'a, T: Serialize> {
     s: Str<'a>,
     // #[schemars(with = "HashMap::<_, HashSet<_>>")]
     // map: BTreeMap<String, BTreeSet<String>>,
-    #[schemars(with = "HashMap::<String, HashSet<String>>")]
+    #[schemars(with = "BTreeMap::<String, BTreeSet<String>>")]
     fake_map: (),
 }
 

schemars/tests/util/mod.rs

@@ -1,7 +1,11 @@
 use pretty_assertions::assert_eq;
 use schemars::{gen::SchemaSettings, schema_for, JsonSchema, Schema};
 use std::error::Error;
+use std::format;
 use std::fs;
+use std::prelude::rust_2021::*;
+
+extern crate std;
 
 pub type TestResult = Result<(), Box<dyn Error>>;
 

schemars/tests/validate.rs

@@ -1,6 +1,6 @@
 mod util;
 use schemars::JsonSchema;
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 use util::*;
 
 // In real code, this would typically be a Regex, potentially created in a `lazy_static!`.
@@ -39,7 +39,7 @@ pub struct Struct {
     #[validate(length(equal = 2))]
     pair: Vec<i32>,
     #[validate(contains = "map_key")]
-    map_contains: HashMap<String, ()>,
+    map_contains: BTreeMap<String, ()>,
     #[validate(required)]
     required_option: Option<bool>,
     #[validate(required)]
@@ -91,7 +91,7 @@ pub struct Struct2 {
     #[schemars(length(equal = 2))]
     pair: Vec<i32>,
     #[schemars(contains = "map_key")]
-    map_contains: HashMap<String, ()>,
+    map_contains: BTreeMap<String, ()>,
     #[schemars(required)]
     required_option: Option<bool>,
     #[schemars(required)]