packages/config: added must* variant for reading required primitive values

packages/config/src/reader.test.ts

@@ -49,6 +49,10 @@ function expectValidValues(config: ConfigReader) {
     'string1',
     'string2',
   ]);
+  expect(config.mustNumber('zero')).toBe(0);
+  expect(config.mustBoolean('true')).toBe(true);
+  expect(config.mustString('string')).toBe('string');
+  expect(config.mustStringArray('strings')).toEqual(['string1', 'string2']);
 
   const [config1, config2, config3] = config.getConfigArray('nestlings');
   expect(config1.getBoolean('boolean')).toBe(true);
@@ -57,6 +61,9 @@ function expectValidValues(config: ConfigReader) {
 }
 
 function expectInvalidValues(config: ConfigReader) {
+  expect(() => config.getBoolean('string')).toThrow(
+    'Invalid type in config for key string, got string, wanted boolean',
+  );
   expect(() => config.getNumber('string')).toThrow(
     'Invalid type in config for key string, got string, wanted number',
   );
@@ -87,6 +94,18 @@ function expectInvalidValues(config: ConfigReader) {
   expect(() => config.getConfigArray('one')).toThrow(
     'Invalid type in config for key one, got number, wanted object-array',
   );
+  expect(() => config.mustBoolean('missing')).toThrow(
+    "Missing required config value at 'missing'",
+  );
+  expect(() => config.mustNumber('missing')).toThrow(
+    "Missing required config value at 'missing'",
+  );
+  expect(() => config.mustString('missing')).toThrow(
+    "Missing required config value at 'missing'",
+  );
+  expect(() => config.mustStringArray('missing')).toThrow(
+    "Missing required config value at 'missing'",
+  );
 }
 
 describe('ConfigReader', () => {
@@ -210,6 +229,12 @@ describe('ConfigReader with fallback', () => {
     // Config arrays aren't merged either
     expect(config.getConfigArray('merged.configs').length).toBe(1);
     expect(config.getConfigArray('merged.configs')[0].getString('a')).toBe('a');
+    expect(config.getConfigArray('merged.configs')[0].mustString('a')).toBe(
+      'a',
+    );
+    expect(() =>
+      config.getConfigArray('merged.configs')[0].mustString('missing'),
+    ).toThrow("Missing required config value at 'missing'");
     expect(
       config.getConfigArray('merged.configs')[0].getString('b'),
     ).toBeUndefined();

packages/config/src/reader.ts

@@ -92,6 +92,14 @@ export class ConfigReader implements Config {
     return (configs ?? []).map(obj => new ConfigReader(obj));
   }
 
+  mustNumber(key: string): number {
+    const value = this.getNumber(key);
+    if (value === undefined) {
+      throw new Error(`Missing required config value at '${key}'`);
+    }
+    return value;
+  }
+
   getNumber(key: string): number | undefined {
     return this.readConfigValue(
       key,
@@ -99,6 +107,14 @@ export class ConfigReader implements Config {
     );
   }
 
+  mustBoolean(key: string): boolean {
+    const value = this.getBoolean(key);
+    if (value === undefined) {
+      throw new Error(`Missing required config value at '${key}'`);
+    }
+    return value;
+  }
+
   getBoolean(key: string): boolean | undefined {
     return this.readConfigValue(
       key,
@@ -106,6 +122,14 @@ export class ConfigReader implements Config {
     );
   }
 
+  mustString(key: string): string {
+    const value = this.getString(key);
+    if (value === undefined) {
+      throw new Error(`Missing required config value at '${key}'`);
+    }
+    return value;
+  }
+
   getString(key: string): string | undefined {
     return this.readConfigValue(
       key,
@@ -114,6 +138,14 @@ export class ConfigReader implements Config {
     );
   }
 
+  mustStringArray(key: string): string[] {
+    const value = this.getStringArray(key);
+    if (value === undefined) {
+      throw new Error(`Missing required config value at '${key}'`);
+    }
+    return value;
+  }
+
   getStringArray(key: string): string[] | undefined {
     return this.readConfigValue(key, values => {
       if (!Array.isArray(values)) {

packages/config/src/types.ts

@@ -32,10 +32,14 @@ export type Config = {
   getConfigArray(key: string): Config[];
 
   getNumber(key: string): number | undefined;
+  mustNumber(key: string): number;
 
   getBoolean(key: string): boolean | undefined;
+  mustBoolean(key: string): boolean;
 
   getString(key: string): string | undefined;
+  mustString(key: string): string;
 
   getStringArray(key: string): string[] | undefined;
+  mustStringArray(key: string): string[];
 };