Error: StaticInjectorError(t)[t -> function(){}]:

Đọc page1.spec.ts và cấu hình kiểm thử được sử dụng bởi ví dụ Ionic Karma/Jasmine, sau đó tái hiện bài kiểm thử signup phát ra StaticInjectorError và NullInjectorError. Truy vết provider còn thiếu từ lỗi được báo cáo và so sánh với cấu hình kiểm thử đang hoạt động; hoàn tất khi bài kiểm thử chạy mà không gặp lỗi injector này.

wrote same code as in page1.spec.ts still getting this error.

Error: StaticInjectorError(t)[t -> function(){}]:
StaticInjectorError(Platform: core)[t -> function(){}]:
NullInjectorError: No provider for function(){}!
error properties: Object({ ngTempTokenPath: null, ngTokenPath: [ 't', Function ], ngDebugContext: t({ view: Object({ def: Object({ factory: Function, nodeFlags: 33669121, rootNodeFlags: 33554433, nodeMatchedQueries: 0, flags: 0, nodes: [ Object({ nodeIndex: 0, parent: null, renderParent: null, bindingIndex: 0, outputIndex: 0, checkIndex: 0, flags: 33554433, childFlags: 114688, directChildFlags: 114688, childMatchedQueries: 0, matchedQueries: Object({ }), matchedQueryIds: 0, references: Object({ }), ngContentIndex: null, childCount: 1, bindings: [ ], bindingFlags: 0, outputs: [ ], element: Object({ ns: '', name: 'signup', attrs: [ ], template: null, componentProvider: Object({ nodeIndex: 1, parent: , renderParent: , bindingIndex: 0, outputIndex: 0, checkIndex: 1, flags: 114688, childFlags: 0, directChildFlags: 0, childMatchedQueries: 0, matchedQueries: Object, matchedQueryIds: 0, references: Object, ngContentIndex: -1, childCount: 0, bindings: ...
at t.get (webpack:///node_modules/@angular/core/esm5/core.js:1003 <- test-config/karma-test-shim.js:45:142)
at webpack:///node_modules/@angular/core/esm5/core.js:1301 <- test-config/karma-test-shim.js:52:2444
at yt (webpack:///node_modules/@angular/core/esm5/core.js:1243 <- test-config/karma-test-shim.js:52:2462)
at t.get (webpack:///node_modules/@angular/core/esm5/core.js:1111 <- test-config/karma-test-shim.js:52:1621) at webpack:///node_modules/@angular/core/esm5/core.js:1301 <- test-config/karma-test-shim.js:52:2444
at yt (webpack:///node_modules/@angular/core/esm5/core.js:1243 <- test-config/karma-test-shim.js:52:2462)
at t.get (webpack:///node_modules/@angular/core/esm5/core.js:1111 <- test-config/karma-test-shim.js:52:1621) at hi (webpack:///node_modules/@angular/core/esm5/core.js:10896 <- test-config/karma-test-shim.js:298:683)