fix: result was wrong if only 1 point

src/SpectrumGenerator.ts

@@ -276,6 +276,7 @@ export class SpectrumGenerator {
       Math.ceil((lastValue - this.from) / this.interval),
     );
     const middlePoint = Math.round((xPosition - this.from) / this.interval);
+
     // PEAK SHAPE MAY BE ASYMMETRC (widthLeft and widthRight) !
     // we calculate the left part of the shape
 
@@ -351,12 +352,13 @@ export class SpectrumGenerator {
    * Resets the generator with an empty spectrum.
    */
   public reset() {
-    const spectrum = this.data;
-
-    for (let i = 0; i < this.nbPoints; i++) {
-      spectrum.x[i] = this.from + i * this.interval;
+    if (this.nbPoints === 1) {
+      this.data.x[0] = (this.from + this.to) / 2;
+    } else {
+      for (let i = 0; i < this.nbPoints; i++) {
+        this.data.x[i] = this.from + i * this.interval;
+      }
     }
-
     return this;
   }
 }

src/__tests__/generateSpectrum.test.ts

@@ -33,6 +33,40 @@ describe('generateSpectrum', () => {
 });
 
 describe('generateSpectrum with one peak and small window', () => {
+  it('No points', () => {
+    const spectrum = generateSpectrum([{ x: 1, y: 10 }], {
+      generator: {
+        from: 0,
+        to: 2,
+        nbPoints: 0,
+        peakWidthFct: () => 0.1,
+        shape: {
+          kind: 'gaussian',
+        },
+      },
+    });
+    expect(spectrum).toStrictEqual({
+      x: Float64Array.from([]),
+      y: Float64Array.from([]),
+    });
+  });
+  it('Very small window, only 1 point', () => {
+    const spectrum = generateSpectrum([{ x: 1, y: 10 }], {
+      generator: {
+        from: 0,
+        to: 2,
+        nbPoints: 1,
+        peakWidthFct: () => 0.1,
+        shape: {
+          kind: 'gaussian',
+        },
+      },
+    });
+    expect(spectrum).toStrictEqual({
+      x: Float64Array.from([1]),
+      y: Float64Array.from([10]),
+    });
+  });
   it('should work with shape 9/3, peak width 0.2', () => {
     const spectrum = generateSpectrum([[10, 1]], {
       generator: {