Improved error handling for image loading

Author: s1hofmann

lib/adapter/vision.adapter.class.ts

@@ -57,8 +57,14 @@ export class VisionAdapter {
   public async findOnScreenRegion(
     matchRequest: MatchRequest,
   ): Promise<MatchResult> {
-    const matchResult = await this.finder.findMatch(matchRequest);
-    return Promise.resolve(matchResult);
+    return new Promise<MatchResult>(async (resolve, reject) => {
+      try {
+        const matchResult = await this.finder.findMatch(matchRequest);
+        resolve(matchResult);
+      } catch (e) {
+        reject(e);
+      }
+    });
   }
 
   /**

lib/provider/opencv/template-matching-finder.class.spec.ts

@@ -62,6 +62,6 @@ describe("Template-matching finder", () => {
     // THEN
     await expect(result)
       .rejects
-      .toEqual(`Failed to load ${pathToHaystack}. Reason: 'Failed to load image from '${pathToHaystack}''.`);
+      .toThrowError(`Failed to load ${pathToHaystack}. Reason: 'Failed to load image from '${pathToHaystack}''.`);
   });
 });

lib/provider/opencv/template-matching-finder.class.ts

@@ -198,7 +198,7 @@ export class TemplateMatchingFinder implements FinderInterface {
         }
         resolve(matches[0]);
       } catch (e) {
-        reject(e.message);
+        reject(e);
       }
     });
   }

lib/screen.class.spec.ts

@@ -61,6 +61,21 @@ describe("Screen.", () => {
       .toEqual(`No match for ${imagePath}. Required: ${SUT.config.confidence}, given: ${matchResult.confidence}`);
   });
 
+  it("should reject when search fails.", async () => {
+    const rejectionReason = "Search failed.";
+    VisionAdapter.prototype.findOnScreenRegion = jest.fn(() => {
+      return Promise.reject(rejectionReason);
+    });
+
+    const visionAdapterMock = new VisionAdapter();
+
+    const SUT = new Screen(visionAdapterMock);
+    const imagePath = "test/path/to/image.png";
+    await expect(SUT.find(imagePath))
+      .rejects
+      .toEqual(`Searching for ${imagePath} failed. Reason: '${rejectionReason}'`);
+  });
+
   it("should override default confidence value with parameter.", async () => {
     const minMatch = 0.8;
     const matchResult = new MatchResult(minMatch, searchRegion);

lib/screen.class.ts

@@ -44,16 +44,21 @@ export class Screen {
       minMatch,
     );
 
-    const matchResult = await this.vision.findOnScreenRegion(matchRequest);
-
-    return new Promise<Region>((resolve, reject) => {
-      if (matchResult.confidence >= minMatch) {
-        resolve(matchResult.location);
-      } else {
+    return new Promise<Region>(async (resolve, reject) => {
+      try {
+        const matchResult = await this.vision.findOnScreenRegion(matchRequest);
+        if (matchResult.confidence >= minMatch) {
+          resolve(matchResult.location);
+        } else {
+          reject(
+            `No match for ${pathToNeedle}. Required: ${minMatch}, given: ${
+              matchResult.confidence
+              }`,
+          );
+        }
+      } catch (e) {
         reject(
-          `No match for ${pathToNeedle}. Required: ${minMatch}, given: ${
-            matchResult.confidence
-            }`,
+          `Searching for ${pathToNeedle} failed. Reason: '${e}'`,
         );
       }
     });