Add template library loading from FileSystem

Tests/HummingbirdMustacheTests/PartialTests.swift

@@ -0,0 +1,54 @@
+import XCTest
+@testable import HummingbirdMustache
+
+final class PartialTests: XCTestCase {
+
+    /// Testing partials
+    func testMustacheManualExample9() throws {
+        let library = HBMustacheLibrary()
+        let template = try HBMustacheTemplate(string: """
+            <h2>Names</h2>
+            {{#names}}
+              {{> user}}
+            {{/names}}
+            """)
+        let template2 = try HBMustacheTemplate(string: """
+            <strong>{{.}}</strong>
+            """)
+        library.register(template, named: "base")
+        library.register(template2, named: "user")
+        
+        let object: [String: Any] = ["names": ["john", "adam", "claire"]]
+        XCTAssertEqual(library.render(object, withTemplateNamed: "base"), """
+            <h2>Names</h2>
+              <strong>john</strong>
+              <strong>adam</strong>
+              <strong>claire</strong>
+
+            """)
+    }
+
+    /// Testing dynamic partials
+    func testDynamicPartials() throws {
+        let library = HBMustacheLibrary()
+        let template = try HBMustacheTemplate(string: """
+            <h2>Names</h2>
+            {{partial}}
+            """)
+        let template2 = try HBMustacheTemplate(string: """
+            {{#names}}
+              <strong>{{.}}</strong>
+            {{/names}}
+            """)
+        library.register(template, named: "base")
+        
+        let object: [String: Any] = ["names": ["john", "adam", "claire"], "partial": template2]
+        XCTAssertEqual(library.render(object, withTemplateNamed: "base"), """
+            <h2>Names</h2>
+              <strong>john</strong>
+              <strong>adam</strong>
+              <strong>claire</strong>
+
+            """)
+    }
+}