test: cover types' base cases

Author: castarco

lambda-ioc/src/__tests__/container.test.ts

@@ -1,5 +1,7 @@
-import { createContainer } from '..'
+/* eslint-disable @typescript-eslint/ban-types */
+import { Container, createContainer } from '..'
 
+// Behavioural tests
 describe('container', () => {
   it('can register simple values', () => {
     const container = createContainer()
@@ -75,3 +77,119 @@ describe('container', () => {
     expect(await c2.resolveAsync('ab')).toBe(21)
   })
 })
+
+// Type tests
+describe('@types/container', () => {
+  it('has the correct type when created for the first time', () => {
+    const c = createContainer()
+    type C = typeof c
+    type C_extends_Container = C extends Container<{}, {}> ? true : false
+    type Container_extends_C = Container<{}, {}> extends C ? true : false
+    type C_is_Container = C_extends_Container extends true
+      ? Container_extends_C extends true
+        ? true
+        : false
+      : false
+    const c_is_Container: C_is_Container = true
+    expect(c_is_Container).toBe(true)
+  })
+
+  it('has the correct type after register call', () => {
+    const c = createContainer().register('a', () => 1)
+
+    type C = typeof c
+    type TargetType = Container<{ a: number }, {}>
+
+    type C_extends_TargetType = C extends TargetType ? true : false
+    type TargetType_extends_C = TargetType extends C ? true : false
+    type C_is_TargetType = C_extends_TargetType extends true
+      ? TargetType_extends_C extends true
+        ? true
+        : false
+      : false
+    const c_is_TargetType: C_is_TargetType = true
+    expect(c_is_TargetType).toBe(true)
+  })
+
+  it('has the correct type after registerAsync call', () => {
+    const c = createContainer().registerAsync(
+      'b',
+      async () => await Promise.resolve(1),
+    )
+
+    type C = typeof c
+    type TargetType = Container<{}, { b: number }>
+
+    type C_extends_TargetType = C extends TargetType ? true : false
+    type TargetType_extends_C = TargetType extends C ? true : false
+    type C_is_TargetType = C_extends_TargetType extends true
+      ? TargetType_extends_C extends true
+        ? true
+        : false
+      : false
+    const c_is_TargetType: C_is_TargetType = true
+    expect(c_is_TargetType).toBe(true)
+  })
+
+  it('resolves nothing when the container is empty', () => {
+    type C = Container<{}, {}>
+
+    // Checking what can be synchronously resolved (it should be nothing)
+    type C_resolve_Parameters = Parameters<C['resolve']>
+    type C_resolve_Parameters_is_never = C_resolve_Parameters extends [never]
+      ? true
+      : false
+    const c_cannot_resolve_anything: C_resolve_Parameters_is_never = true
+    expect(c_cannot_resolve_anything).toBe(true)
+
+    // Checking what can be asynchronously resolved (it should be nothing)
+    type C_resolveAsync_Parameters = Parameters<C['resolveAsync']>
+    type C_resolveAsync_Parameters_is_never =
+      C_resolveAsync_Parameters extends [never] ? true : false
+    const c_cannot_resolveAsync_anything: C_resolveAsync_Parameters_is_never =
+      true
+    expect(c_cannot_resolveAsync_anything).toBe(true)
+  })
+
+  it('only resolves the sync registered dependency', () => {
+    type C = Container<{ a: number }, {}>
+
+    // Checking what can be synchronously resolved (it should be just 'a')
+    type C_resolve_Parameters = Parameters<C['resolve']>
+    type C_resolve_Parameters_is_a = C_resolve_Parameters extends ['a']
+      ? true
+      : false
+    const c_can_only_resolve_a: C_resolve_Parameters_is_a = true
+    expect(c_can_only_resolve_a).toBe(true)
+
+    // Checking what can be asynchronously resolved (it should be nothing)
+    type C_resolveAsync_Parameters = Parameters<C['resolveAsync']>
+    type C_resolveAsync_Parameters_is_never =
+      C_resolveAsync_Parameters extends [never] ? true : false
+    const c_cannot_resolveAsync_anything: C_resolveAsync_Parameters_is_never =
+      true
+    expect(c_cannot_resolveAsync_anything).toBe(true)
+  })
+
+  it('only resolves the async registered dependency', () => {
+    type C = Container<{}, { b: number }>
+
+    // Checking what can be synchronously resolved (it should be nothing)
+    type C_resolve_Parameters = Parameters<C['resolve']>
+    type C_resolve_Parameters_is_never = C_resolve_Parameters extends [never]
+      ? true
+      : false
+    const c_cannot_resolve_anything: C_resolve_Parameters_is_never = true
+    expect(c_cannot_resolve_anything).toBe(true)
+
+    // Checking what can be asynchronously resolved (it should be just 'b)
+    type C_resolveAsync_Parameters = Parameters<C['resolveAsync']>
+    type C_resolveAsync_Parameters_is_b = C_resolveAsync_Parameters extends [
+      'b',
+    ]
+      ? true
+      : false
+    const c_can_only_resolve_b: C_resolveAsync_Parameters_is_b = true
+    expect(c_can_only_resolve_b).toBe(true)
+  })
+})